24-hour Urine Collection Research Articles

Predicting urinary stone recurrence: a joint model analysis of repeated 24-hour urine collections from the MSTONE database

To address the limitations in existing urinary stone recurrence (USR) models, including failure to account for changes in 24-hour urine (24U) parameters over time and ignoring multiplicity of stone recurrences, we presented a novel statistical method to jointly model temporal trends in 24U parameters and multiple recurrent stone events. The MSTONE database spanning May 2001 to April 2015 was analyzed. A joint recurrent model was employed, combining a linear mixed-effects model for longitudinal 24U parameters and a recurrent event model with a dynamic first-order Autoregressive (AR(1)) structure. A mixture cure component was included to handle patient heterogeneity. Comparisons were made with existing methods, multivariable Cox regression and conditional Prentice-Williams-Peterson regression, both applied to established nomograms. Among 396 patients (median follow-up of 2.93 years; IQR, 1.53–4.36 years), 34.6% remained free of stone recurrence throughout the study period, 30.0% experienced a single recurrence, and 35.4% had multiple recurrences. The joint recurrent model with a mixture cure component identified significant associations between 24U parameters - including urine pH (adjusted HR = 1.991; 95% CI 1.490–2.660; p < 0.001), total volume (adjusted HR = 0.700; 95% CI 0.501–0.977; p = 0.036), potassium (adjusted HR = 0.983; 95% CI 0.974–0.991; p < 0.001), uric acid (adjusted HR = 1.528; 95% CI 1.105–2.113, p = 0.010), calcium (adjusted HR = 1.164; 95% CI 1.052–1.289; p = 0.003), and citrate (adjusted HR = 0.796; 95% CI 0.706–0.897; p < 0.001), and USR, achieving better predictive performance compared to existing methods. 24U parameters play an important role in prevention of USR, and therefore, patients with a history of stones are recommended to closely monitor for future recurrence by regularly conducting 24U tests.

Proximal Tubule Secretory Clearance, Injury, and Kidney Viability in Cirrhosis.

Cirrhosis affects all structures of the kidney, in particular the tubules which are responsible for secretion of protein-bound metabolites and electrolyte/water homeostasis. Yet, prevailing assessments of kidney function focus solely on glomerular filtration rate (GFR) which may incompletely reflect these processes. We sought to characterize markers of tubular function, injury, and viability in patients with and without cirrhosis. We recruited outpatients undergoing liver transplantation evaluation for a collection of plasma and 24-hour urine, matching by GFR to control participants without cirrhosis. We measured urinary kidney injury molecule-1 (KIM-1), a marker of proximal tubular injury, as well as epidermal growth factor (EGF), a marker of viability necessary for tubular epithelial cell proliferation after injury. We also estimated secretory clearance by measuring several highly secreted endogenous metabolites in urine and plasma. We recruited 39 patients with cirrhosis (mean MELD-Na 17±4, Child-Pugh 8±2, eGFR 66±20 ml/min/1.73m2) and 58 GFR-matched controls without cirrhosis (eGFR 66±21 ml/min/1.73m2). Urinary KIM-1 was 4.4-fold higher than controls (95% CI:2.9-6.5), and EGF averaged 7.41-fold higher than controls (95% CI:2.15-25.53). We found that of 8 solutes, 5 had significantly greater kidney clearance in cirrhosis (1.3-2.1-fold higher): indoxyl sulfate, p-cresol sulfate, pyridoxic acid, tiglylglycine, and xanthosine. Cirrhosis was characterized by molecular signs of tubular injury in stable outpatients without acute kidney injury, accompanied by largely preserved tubular secretory clearance and greater signs of tubular viability. Within the limitations of the study, this suggests a phenotype of chronic ischemic injury but with initial preservation of tubular function in cirrhosis.

6940 Thrombotic Events in Primary Hyperparathyroidism: Association or Coincidence?

Abstract Disclosure: I.A. Guatemala Funes: None. Z. Zavgorodneva: None. Y. EL-Soufi: None. A. Khan: None. T. Zahedi: None. F. Zhang: None. Introduction: The classical manifestations of primary hyperparathyroidism are nephrolithiasis, osteoporosis, and hypercalcemia-related symptoms, such as abdominal pain, constipation, polydipsia, and polyuria. Parathyroid crisis is a rare and life-threatening presentation of primary hyperparathyroidism characterized by calcium levels above 14-15 mg/dl and marked symptoms of hypercalcemia. Here, we describe a rare case of bilateral pulmonary embolism in a patient with severe hypercalcemia secondary to parathyroid adenoma. Case Report The patient is a 70-year-old female with a past medical history of primary hyperparathyroidism, who presented with profound fatigue, shortness of breath, polyuria and constipation. The patient denied any trauma, immobilization, or long-distance travel. On physical exam patient was confused, dehydrated, and nonhypoxic but with increased work of breathing. Initial labs showed severe hypercalcemia with calcium 19.2 mg/dL, significant elevated PTH 1113.9 pg/mL from her baseline PTH 380.8 pg/mL, normal 25 VitD, and acute kidney injury with creatinine increased from 0.9 mg/dL to 2.8 mg/dL. The calcium level in 24-hour urine collection was 323 mg/24 hours. CT chest angiogram revealed a bilateral lower lobe pulmonary embolism. The lower extremity duplex was negative for venous thrombosis. Thyroid ultrasound demonstrated suspected left parathyroid adenoma 2.1 x 2.1 x 1.4 cm. Renal ultrasound was negative for renal calculi. Following treatment with intravenous fluids, Calcitonin, and Denosumab, her calcium level improved to 10.1 mg/dL. The patient’s symptoms improved and underwent parathyroidectomy. PTH levels decreased significantly after parathyroidectomy. Pathology report confirmed parathyroid adenoma. Discussion The association between hypercalcemia and venous or arterial thrombosis has been rarely reported. Calcium participates directly in the platelet activation, platelet aggregation, and coagulation cascade. However, the true correlation between hypercalcemia and thrombosis is not well understood. It is believed that indirect factors such as vasoconstriction, dehydration, and cytotoxic effects due to hypercalcemia and the direct effects over platelet function and coagulation, may act together to induce thrombosis. Unfortunately, much of the evidence between hypercalcemia and hypercoagulability is based on case reports and our case could be one more evidence that this correlation exists. The patient’s age, absence of other risk factors of hypercoagulability, simultaneous manifestation of hypercalcemic crisis, and acute PE make hypercalcemia as a more likely pathogenetic origin of thrombus formation. Conclusion: Physicians should be cautious of the hypercalcemia-induced thrombotic events caused by dehydration and calcium-triggered vasoconstriction, clotting system activation, or platelet aggregation. Presentation: 6/3/2024

8774 An Uncommon Presentation Of A Large Silent Pheochromocytoma

Abstract Disclosure: M. Lozano: None. A. Pinero-Pilona: None. Background: The reported estimated incidence of pheochromocytoma is approximately 2-8 cases per 1 million people per year. Of those, silent pheochromocytomas will make up about 8%. Thus, biochemically silent and non-secreting pheochromocytomas are a very rare phenomenon. Clinical Case: A 74-year-old Caucasian female with significant past medical history of primary hypothyroidism, hypercholesterolemia, and nasal sinus carcinoma s/p surgery (in remission) presented to the clinic for endocrine evaluation of a right adrenal mass. The patient was asymptomatic and denied headaches, tachycardia, sweating, severe hypertension, diabetes, muscle weakness, easy bruising, or striae. The mass was initially diagnosed as an incidental finding after a contrast CT scan of the abdomen was performed for diverticulitis. The right adrenal enhancing mass was 2.3 x 3.9 x 4.1 cm in diameter. Subsequent MRI abdomen with and without contrast ordered by the referring physician showed that the adrenal mass had grown to 4.9 x 3.8 x 5.4 cm and was hyperenhancing in nature with central T2 hyperintense signal. Notably, multiple “parasitized and arborealized” vessels were detected within the mass. Such findings led us to suspect metastatic versus primary adrenal neoplasm such as cortical carcinoma as a working diagnosis. Other laboratory studies including plasma free metanephrines (&amp;lt;10 pg/mL, normal 0-88 pg/mL), plasma normetanephrines (29.2 pg/mL, normal 0-285.2 pg/mL) and 24-hour urine collections (24 hr urine epinephrine - 3 ug/24 hr [normal 0-20 ug/24 hr]; 24 hr urine norepinephrine - 75 ug/24 hr [normal 0-135 ug/24 hr]; 24 hr urine VMA - 3 mg/24 hr [normal 0-7.5 mg/24 hr]) were negative for pheochromocytoma. As her mass was greater than 4 cm in diameter, surgical referral was then recommended to the patient. Right adrenalectomy was performed. Pathology report was consistent with pheochromocytoma as supported by immunohistochemistry. Ki-67 proliferation index was 0-10% (average 3-4%, rare hotspots 10%). Atrophy and vascular ectasia were present in residual non-neoplastic adrenal cortex and medulla. Histology showed a nested growth pattern, absence of composite tumor elements, absence of necrosis, and no atypical mitoses. The incidence of non-secreting pheochromocytomas has been quoted to be 0.000064% (1). Conclusion: The case illustrates an uncommon presentation of a large, silent pheochromocytoma with negative plasma metanephrines accompanied by negative urine studies, which have a negative predictive value close to 100% in ruling out a pheochromocytoma. Our case emphasizes the importance of considering pheochromocytoma on the differential of adrenal masses with high attenuation or high enhancement even when biochemical studies suggest otherwise. Reference: (1) Radojkovic, D., et al. "CLINICALLY" SILENT GIANT PHEOCHROMOCYTOMA. CASE REPORT." Acta Endocrinologica (1841-0987) 9.1 (2013). Presentation: 6/1/2024

8155 Isolated Hypothalamic-Pituitary Langerhans' Cell Histiocytosis in Adult Patients

Abstract Disclosure: A. Vu: None. M. Aguilera: None. J. Shakil: None. R. Al-Ward: None. Introduction: Langerhans cell histiocytosis (LCH) is an infiltrative disease due to clonal proliferation of immature dendritic cells mainly affecting children and seen in adults in less than 30% of cases. It can present as localized or with systemic manifestations, with isolated hypothalamic-pituitary lesions being exceptionally rare. Our report adds to the limited published literature by presenting two cases of isolated hypothalamic-pituitary LCH diagnosed in adults. Furthermore, one of the cases reveals a rare association with papillary thyroid cancer (PTC). Case 1: 35-year-old woman with no past medical history presented with 4 year history of amenorrhea and weight gain and more recently, polyuria and polydipsia. Further investigations showed hypogonadotropic hypogonadism, central hypothyroidism, and mildly elevated prolactin. She couldn’t complete water deprivation test due to extreme thirst. A dedicated pituitary MRI showed marked infundibular enlargement, concerning for hypophysitis. An extensive workup including assessments for autoimmune etiology, sarcoidosis, infections, and low-grade tumors, did not identify a definitive etiology. A PET scan was obtained (to rule out LCH and Erdheim Chester disease), which showed increased uptake in the pituitary stalk. Due to otherwise negative workup, transsphenoidal biopsy of the pituitary lesion was done. Post-procedure, diabetes insipidus (DI) was diagnosed due to elevated sodium while fasting for the procedure. Tissue examination revealed increased histiocytes and lymphocytes, and a positive BRAF V600E mutation confirming LCH as the underlying diagnosis. Case 2: 26-year-old male with history of LCH limited to the skull, in remission for 8 years after chemotherapy, presented with 4-week history of polyuria, polydipsia and weight loss. A 24-hour urine collection resulted in 6.5L of urine. During water deprivation test, there was notable increase in serum sodium, serum osmolarity, and urine osmolarity. Initial pituitary MRI was normal, but subsequent imaging revealed the loss of the posterior pituitary bright spot. PET scan showed focal FDG avidity in the right lower thyroid lobe, confirmed on fine needle aspiration as PTC with BRAF mutation. He underwent total thyroidectomy and is currently receiving chemotherapy for LCH recurrence. Discussion: LCH is infrequent in adults, presenting with variable manifestations based on affected organs. In the multifocal form, the hypothalamic-pituitary axis is involved in 5-50% of cases. Our report describes two unique cases with only four other reported cases of isolated hypothalamic-pituitary axis LCH in adults. Central diabetes insipidus can be seen before the diagnosis or as the disease progresses. Pituitary biopsy, although invasive, should be considered when the diagnosis is not clear. The association of PTC with a BRAF mutation is extremely rare and has been reported. Presentation: 6/2/2024

Adult-Onset IgA Vasculitis Complicated by Kidney Failure at Disease Onset in a Nepalese Patient: A Case Report

Introduction: Immunoglobulin A (IgA) vasculitis, previously known as Henoch-Schönlein purpura, is an immune complex-mediated small vessel vasculitis primarily affecting children. While rare in adults, it can present with more severe manifestations, particularly involving the kidneys. This case report details the presentation and management of adult-onset IgA vasculitis with significant renal involvement.  Case Report: A 43-year-old male with a history of bipolar disorder presented with facial swelling, shortness of breath, and decreased urine output following an upper respiratory infection. Initial investigations revealed elevated blood pressure and renal impairment. Despite supportive treatment, his condition worsened, leading to a referral to a tertiary care center. He exhibited symptoms consistent with IgA vasculitis, including joint pain, rash, and nephrotic-range proteinuria. The diagnosis was confirmed through a skin biopsy and 24-hour urine collection. The patient was treated with intravenous methylprednisolone, oral prednisone, and an ACE inhibitor. His renal function improved with this regimen.  Discussion: Adult-onset IgA vasculitis can present with severe kidney involvement, including nephrotic-range proteinuria and elevated serum creatinine, which are associated with poorer outcomes compared to pediatric cases. The patient's management, involving glucocorticoids and an ACE inhibitor, aligns with current treatment recommendations for significant renal involvement. Long-term prognosis in adults remains challenging, with a higher risk of end-stage kidney disease compared to children. Vigilant monitoring and tailored treatment strategies are crucial for improving outcomes.  Conclusion: This case underscores the potential severity of adult- onset IgA vasculitis and highlights the importance of early diagnosis and aggressive management to mitigate long- term renal complications. Ongoing research is necessary to refine treatment approaches and enhance outcomes for adults with this condition.

Changes in 24-Hour Urine Chemistry in Patients with Nephrolithiasis during Weight Loss with Glucagon-Like Peptide 1-Based Therapies.

Key Points In obese kidney stone formers, weight loss with glucagon-like peptide-1 (GLP)-based therapy was associated with a significant decline in 24-hour urine oxalate and sulfate excretion rates.Weight loss through GLP-based therapies was associated with nonsignificant changes in urine saturation indices.In obese kidney stone formers, GLP-based therapy appears to be a safe option for weight loss on the basis of 24-hour urine studies. Background Obesity is an independent risk factor of incident and recurrent nephrolithiasis. The effect of weight loss through glucagon-like peptide 1 (GLP-1) receptor agonists and dual GLP-1/gastric inhibitory polypeptide receptor agonists (GLP-based therapies) on nephrolithiasis is not well understood. This study examined the changes in 24-hour urine chemistry assessing for stone risk during weight loss through GLP-based therapies. Methods This retrospective analysis identified adult stone formers followed at our academic institution's weight wellness clinic between September 2015 and August 2023 and included patients with at least two 24-hour urine collections for stone risk assessment. 24-hour urine parameters before and during weight loss in patients on GLP-based therapies were compared. Results Forty-four obese patients with nephrolithiasis experienced significant weight reduction (−6.6±7.3 kg, P &lt; 0.001) over a median 1.1 years of follow-up with GLP-based therapies. During this period, there was a significant decrease in 24-hour urine oxalate (40±16 to 32±11 mg/d, P = 0.002), sulfate (21±10 to 17±9 mmol/d, P = 0005), and ammonium (35±22 to 29±15 mEq/d, P = 0.01) excretion rates. There were nonsignificant changes in urine calcium, citrate, uric acid, pH, phosphorus, sodium, potassium, magnesium, chloride, creatinine, or total volume. In addition, there was no statistical difference in urine supersaturation indices with respect to calcium oxalate, calcium phosphate, and uric acid. Conclusions Our results indicate that weight loss through GLP-based therapies is not associated with prolithogenic changes in 24-hour urine chemistry in patients with nephrolithiasis, unlike what happens with other weight loss modalities.

Porphyria in pregnancy with exacerbation after delivery due to COVID-19

We present a case of acute intermittent porphyria (AIP) diagnosed in a pregnant woman with subsequent exacerbation after delivery due to COVID-19 infection. The patient’s symptoms manifested with acute neurovisceral attacks - abdominal pain followed by flaccid quadriparesis, sensory disturbances, hypertension and disturbance in electrolyte levels. The blood plasma test and a 24-hour urine collection revealed increased levels of urine porphobilinogen, 5-aminolevulinic acid and uroporphyrins, which led to the diagnosis of AIP. The patient received i.v. human hemin with positive outcome. After delivery she was again admitted to the hospital due to abdominal pain and trunk hyperesthesia that occurred after a mild course of COVID-19 infection. The second administration of human hemin led to the improvement of the patient's condition. The aim of this case report is to indicate that even with severe risk factors of AIP such as infection and pregnancy, proper diagnostics can increase the chance of quick recovery.

P176 SPOT URINE FORMULAS OVERESTIMATE DIETARY SODIUM INTAKE DURING LOW SODIUM CONSUMPTION

Background and objective: Long-term sodium balance studies have revealed a phenomenon of temporary storage of sodium in tissues. Consequently, relying on an individual's single 24-hour urine collections may lead to an unreliable estimation of sodium intake. Our recent research has shown that the accuracy of repeated spot urine collections is equal to that of a single 24-hour urine collection at a sodium intake level of 5 gram/day. Since no data is available about the performance at recommended sodium intake (i.e., &lt;2 grams/day), we determined their accuracy during low sodium consumption. Methods: We performed a post-hoc analysis on data from a metabolic ward study in which 16 healthy male adults consumed a diet with a fixed sodium content of 50 or 200 mmol/day for 7 days. Each day, urine was collected in 4 intervals (7:00-13:00 h, 13:00-19:00 h, 19:00-23:00 h, 23:00-07:00 h). We estimated sodium intake by the European Toft formula using urines of the same interval on 3 consecutive days during steady state (day 5-7). In sensitivity analyses we applied the Tanaka and Kawasaki formulas. Results: During a 200-mmol sodium intake, the Toft formula estimates appeared the most accurate, deviating 10 [IQR 3-14], 8 [6-19], 36 [16-49] and 20 [10-43] mmol from the intake for intervals 7:00-13:00 h, 13:00-19:00 h, 19:00-23:00 h, 23:00-07:00 h, respectively (Figure 1A). This accuracy did not significantly differ from a single 24-hour urine (20 [12-55] mmol). However, at a 50-mmol sodium intake, the Toft formula estimates deviated 62 [IQR 45-69], 75 [67-97], 99 [90-109] and 51 [45-61] mmol from the intake for similar intervals (Figure 1B). These estimates were significantly less accurate than a single 24-hour urine (9 [6-23] mmol). Although the Tanaka equation outperformed the Toft equation, this formula was also significantly inferior to a 24-hour urine collection. Conclusions: Repeated spot urine collection substantially overestimates sodium intake when sodium intake is low, whereas it performs similarly to a 24-hour urine collection at an average sodium intake.

O79 DAILY URINARY POTASSIUM EXCRETION IS NOT A FIXED PERCENTAGE OF DAILY POTASSIUM INTAKE

Background and Objective: High potassium intake is associated with a lower blood pressure and lower incidence of cardiovascular events. For estimation of potassium intake, the World Health Organization advices to multiply the 24-hour renal potassium excretion by 1.3, considering the substantial fecal potassium loss. We examined the variation in the required conversion factor in healthy volunteers and evaluated the effect of factors associated with tissue cation storage on the renal potassium excretion. Methods: We performed a post-hoc analysis of the Mars long-term sodium balance studies. Healthy male participants consumed a fixed amount of salt (6, 9 and 12 grams/day for &gt;29 days) and potassium (4 grams/day) for 105 (n=4) and 205 days (n=6). All urine was collected in 24-hour aliquots. We calculated the percentage of potassium intake that was excreted in the corresponding 24-hour urine collection during steady-state. A multivariable mixed-effects model was used to assess associations of this percentage with sodium intake, potassium intake, urinary aldosterone, urinary cortisol and urine volume. Results: The median renal potassium excretion was 80% of potassium intake (IQR 65-97%, range 24-304%), corresponding to a conversion factor of 1.25 (IQR 1.03-1.54). Within individual subjects we also observed a marked day-to-day variation in the percentage of renal potassium excretion: the average intraperson width of the IQR was 25%. Sodium intake (figure A), urinary aldosterone (figure B), urinary cortisol (figure C) and urine volume (figure D) were positively associated with the percentage of renal potassium excretion, whereas potassium intake showed a negative association (figure A). A significant positive interaction between the effects of sodium and potassium intake was present (P&lt;0.001). Conclusions: The percentage of dietary potassium that is excreted via urine varies considerably. During steady-state, this percentage is independently affected by sodium intake, potassium intake, urinary aldosterone, urinary cortisol, and urine volume. Our results suggest that the WHO's fixed 1.3 conversion factor may lead to inaccurate estimations of potassium intake.

O80 A HIGH 24-HOUR URINE SODIUM-TO-POTASSIUM RATIO IS ASSOCIATED WITH WORSE RENAL OUTCOME

Background and Objective: Low sodium and high potassium intake are advised to control blood pressure and may improve long term cardiorenal outcomes. The optimal potassium intake for patients with chronic kidney disease remains to be defined and. We investigated whether the 24-hour urine sodium-to-potassium ratio (Na/K-ratio), which incorporates estimates of both sodium and potassium intake, could predict long-term renal outcome. Methods: We selected adult outpatients of a Dutch tertiary hospital who collected at least one 24-hour urine collection between 1998-2023. Patients with a history of dialysis or kidney transplantation were excluded. We examined the need for persistent renal replacement therapy (RRT), defined as dialysis or kidney transplantation, using Cox-regression. The association between the 24-hour urine Na/K-ratio and the estimated glomerular filtration rate (eGFR) slope was assessed using linear regression in patients who had ≥3 eGFR measurements available in ≥3 years, adjusted for age, sex, baseline eGFR, diabetes mellitus and hypertension. In the Cox-regression analysis, we additionally adjusted for the interaction between the 24-hour urine Na/K-ratio and baseline eGFR. Hypertension was defined as a clinical diagnosis or an office blood pressure ≥140/90 mmHg. Results: We included 720 patients aged 50±15 years, of whom 52% were male, 58% had hypertension and 31% diabetes mellitus. The baseline eGFR was 64±34 ml/min/1.73m2. The 24-hour urine Na/K ratio was 2.5±1.2 in a median number of 1 (IQR=1-2) urine collection. During a median follow-up of 11.2±14.0 years, 29% of patients needed RRT. The median annual eGFR decline was 1.51 (IQR=0.49-3.98) ml/min/1.73m2. Every unit increase in 24-hour urine Na/K-ratio was associated with a 19% higher risk for RRT (HR 1.19, 95% CI 1.03-1.39; p=0.02) and an additional 0.44 ml/min/1.73m2 (95% CI -0.83, -0.04; p=0.03) annual eGFR decline. Conclusions: This study suggests that higher 24-hour urine Na/K-ratio is associated with faster kidney function decline and the need for RRT, independent of hypertension, in a selected group of outpatients with available 24-hour urine measurements.

O39 IMPACT OF UROMODULIN CONCENTRATION ON RENAL AND HAEMODYNAMIC PARAMETERS IN A BLACK AFRICAN COMMUNITY WITH A HIGH PREVALENCE OF HYPERTENSION

Background and Objective: The burden of hypertension (HTN) and related comorbidities disproportionately affects developing countries like South Africa, particularly in urban populations of African ancestry. This demographic exhibits a volume-dependent form of HTN that is resistant to antihypertensive drugs that target the renin-angiotensin-aldosterone system. Renal fluid retention or abnormalities may cause HTN in this group, thus the need to investigate various nephron components for a better understanding. Uromodulin is a potential biomarker for renal function and tubular reserve. However, the relationship with renal function, haemodynamic parameters and HTN in a Black African population is unknown. Therefore, the aim of this study was to explore the relationship between urinary uromodulin concentration and renal as well as haemodynamic parameters in a Black African community with a high prevalence of volume-dependent HTN. Methods: Systemic haemodynamics (central pressures [SphygmoCor] and echocardiographic aortic velocity and diameter measurements in the outflow tract), urinary uromodulin concentrations (ELISA assay) and renal function (creatinine clearance from 24-hour urine collections [n=370]) were determined in a Black African community (n=397). Results: No relationships between urinary uromodulin concentrations and age, body mass index, blood pressure or hypertension were noted. However, urinary uromodulin concentrations were higher in females than males, even after adjusting for several confounders (p=0.0007). Although urinary uromodulin concentrations were unrelated to renal function, an inverse relationship with stroke volume (SV) was observed (p=0.0023). The inverse relationship between SV and urinary uromodulin concentration was independent of confounders and present in hypertensives (p=0.007) but not normotensives (p=0.43). The hypertensives were noted to have a higher SV than the normotensives (p=0.047). Conclusion: In a Black African community sample with a high prevalence of volume-dependent primary hypertension, urinary uromodulin was inversely related to SV, particularly in participants with hypertension. These data suggest the need to investigate the mechanisms linking urinary uromodulin to haemodynamic parameters to identify novel pathways to target for better treatment strategies in hypertension.

Abstract P218: Resistant hypertension is associated with elevated 24-hour cortisol to cortisone ratios in black patients.

Background: RHTN is defined as blood pressure above goal despite using ≥3 antihypertensive medications. Patients with RHTN are at an increased risk for cardiovascular (CVD) compared to those with more easily controlled hypertension (HTN). Blacks With RHTN are at a specifically high risk for CVD. Mineralocorticoid receptor activation has been found as an important mechanism of RHTN. However, aldosterone levels are not different in blacks versus whites. The role of 24-hour cortisol-to-cortisone ratios in this group has not been investigated. Methods: We conducted a cross-sectional analysis of a large cohort of 2397 black and white patients with RHTN who were referred to the RHTN Clinic at the University of Alabama at Birmingham and who underwent 24-hour urine collection including cortisol and cortisone. Patients with HTN served as a control group. Results: Black patients with RHTN compared to whites had a trend to higher 24h cortisol levels (17.7±27.6 vs 16.9±14.9, p =0.70, significantly lower 24h cortisone levels (60.45±37.7 vs 75.3±40.0, p 0.000234), and significantly higher 24h cortisol-to-cortisone ratios (0.23±0.14 vs 0.20 ±0.10, p=0.027). They were younger (53.3±11.6 vs 59.4±12.9 years), more obese (BMI 34.9±7.6 vs 30.8±6.1 kg/m2, p&lt;0.001), had earlier onset of HTN (35.6±12.5 vs 41.4±11.6 years of age, p&lt;0.001), higher 24-hour urinary sodium excretion (188.2±92.5 vs 174.9±83.1 mmol, p=0.006) and lower potassium excretion (54.5 ±28.6 vs 65.5 ±30.5 mmol, p&lt;0.001). Furthermore, they had a significantly higher rate of heart failure (p=0.000455) and diabetes (p=0.0006). Conclusion: Cortisol dysregulation and a higher cortisol-to-cortisone ratio as an index of 11beta HSD2 activity may play a role in black patients with RHTN and may be related to adverse outcomes in this population.

Abstract P331: Simple Instruction and Provision of Literature on Low Salt Diet Ineffective in Reducing Salt Intake in Patients with Hypertension

Objective: Hypertension remains poorly controlled at the population level. Reduction of salt intake via the DASH diet is effective in reducing blood pressure (BP). We enrolled a cohort of patients with hypertension to assess molecular factors that influence BP control over a follow up period of 6 months. Here we report dietary sodium intake and BP control. Methods: 80 non-diabetic patients aged &gt;40 with hypertension were enrolled in the study. Subjects reccieved brief instruction and a handout on the DASH diet from a study coordinator. Medications were titrated to a BP of &lt;130/80 at enrollment, months 1, 2,3 and 6. BP was measured at each visit using an automated cuff following clinical trial methodology. 24-hour urine sodium excretion was collected at enrollment, months 3 and 6. Descriptive variables were summarized and paired t-tests were used to compare sodium excretion and BP. Results: Cohort characteristics are in Table 1. 73 subjects provided 24-hour urine samples and BP at enrollment and month 3 while 67 had samples at enrollment and month 6. Mean BP at enrollment was 129.9/75.3 (SD 16.6/12.5) which reduced 123/71.8 (SD 12.9/10) at month 3, p &lt;0.001and 125.4/73.4 (SD 15.2/10.5), p=0.02. 24-hour sodium excretion was 152 mmol (SD 73.6) at enrollment. There was no difference in sodium excretion at 3- (154 mmol, SD 86.2, p=0.8) or 6 months (139 mmol, SD 60,, p=0.18). Conclusions: According to 24-hour urine collection, participants consumed roughly 3.5 g of sodium per day. Simple instruction and provision of literature regarding a DASH diet was ineffective in reducing sodium intake. Further study is required to determine a more effective educational delivery method and understand any social factors that may inhibit diet implementation in this urban hypertensive cohort.

Impaired Saltiness Perception Contributes to Higher Sodium Intake Among Patients With Chronic Kidney Disease: A Cross-Sectional Two-Center Study

Dietary sodium restriction is important in the prognosis of patients with chronic kidney disease (CKD). The association between saltiness perception and sodium intake among CKD patients is unclear, and the factors that influence saltiness are also not fully understood. We evaluated saltiness perception in CKD patients employing a cost-effective saltiness perception test using sodium solutions and evaluated the association between saltiness perception, sodium intake, and the influencing factors. CKD outpatients not undergoing dialysis were enrolled from two medical centers and underwent saltiness perception tests together with 24-hour urine collections to measure daily sodium intake. Participants who perceived saltiness using the test solution containing 25mM sodium were regarded to have "preserved" saltiness perception, while those unable to perceive saltiness were regarded as having "impaired" saltiness perception. Of the total 132 participants, the median daily sodium intake was 3.36g (range; 0.51-9.95g/day), and 43 (32.6%) were ex- or current smokers. When participants were divided into 3 groups (G) according to daily sodium intake level: low (G1; 0.51-2.61g/day), middle (G2; 2.62-3.99g/day), and high (G3; 4.06-9.95g/day), there was an obvious difference in impaired saltiness perception between three groups: 6.8% in G1, 50.0% in G2 and 86.4% in G3 (P value=8.035 × 10-14, Cochran-Armitage test). In a multiple regression analysis in which the saltiness perception was adopted as a subjective variable, smoking habit (ex- or current smoker) and nonadherence to dietary sodium restriction were identified as significant explanatory variables. We revealed the clear relationship between higher daily sodium intake and impaired saltiness perception that is related to nonadherence to dietary sodium restriction and smoking habit, both of which could be intervened by nutritional counseling and public health education.

A Urine pH-Ammonium Acid/Base Score and CKD Progression.

Acidosis is associated with exacerbated loss of kidney function in chronic kidney disease (CKD). Currently, acid/base status is assessed by plasma measures, although organ-damaging covert acidosis, subclinical acidosis, may be present before reflected in plasma. Low urine NH4+ excretion associates with poor kidney outcomes in CKD and is proposed as a marker for subclinical acidosis. However, low NH4+ excretion could result from either a low capacity or a low demand for acid excretion. We hypothesized that a urine acid/base-score reflecting both the demand and capacity for acid excretion would better predict CKD progression. 24-hour urine collections were included from three clinical studies of patients with CKD stage 3 and 4: A development cohort (n=82), a variation cohort (n=58), and a validation cohort (n=73). A urine acid/base-score was derived and calculated from urinary pH and [NH4+]. Subclinical acidosis was defined as an acid/base-score below the lower limit of the 95% prediction interval of healthy controls. Main outcomes were change in measured GFR after 18 months and CKD progression (defined as ≥50% decline in eGFR, initiation of long-term dialysis or kidney transplantation) during up to 10 years of follow-up. Subclinical acidosis was prevalent in all cohorts (n=54/82, 48/73, and 40/58, ∼67%). Subclinical acidosis was associated with an 18% (95% CI: 2-32) larger decrease of measured GFR after 18 months. During a median follow-up of 6 years, subclinical acidosis was associated with a markedly higher risk for CKD progression. Adjusted hazard ratios were 9.88 (95% CI 1.27-76.7) in the development cohort and 11.1 in the validation cohort (95% CI: 2.88-42.5). The acid/base-score had a higher predictive value for CKD progression than NH4+ excretion alone. Subclinical acidosis, defined by a new urine acid/base-score, was associated with a higher risk of CKD progression in patients with CKD stage 3 and 4.

Sleep, Health Outcomes and Body Weight (SHOW) study: a measurement burst design study on sleep and risk factors for obesity in black emerging adults in North Carolina, USA

IntroductionBlack emerging adults (18–28 years) have the highest risk of short sleep duration and obesity. This increased risk may be partly explained by greater stress levels, which may result from...

Self-Performed Dietary Sodium Reduction and Blood Pressure in Patients With Essential Hypertension: A Randomized Clinical Trial.

Hypertension is the leading risk factor for cardiovascular disease worldwide. Patients with blood pressure (BP) response to dietary sodium reduction are referred to as "salt sensitive." Salt sensitivity (SS) might be due to differences in sodium storage capacity and the erythrocyte SS examines this capacity of the red blood cells. This study aimed to test the effect of a self-performed sodium reduced diet on BP in patients with essential hypertension and examine whether erythrocyte SS predicts SS. Seventy-two patients with hypertension were included and randomized 2:1 to either sodium reduction or a control group for 4 weeks. Blood samples, 24-hour BP measurement, and 24-hour urine collection were performed before and after. The intervention group received advice on how to lower sodium intake. Urinary sodium excretion decreased 66 mmol (95% CI, -96 to -37 mmol) in the intervention group compared with the control group. Systolic 24-hour BP decreased 9 mm Hg after low-sodium diet compared with the control group (95% CI, -13 to -4 mm Hg). Similarly, the difference in reduction in diastolic BP between the groups was 5 mm Hg (95% CI, -8 to -1 mm Hg). We found no correlation between erythrocyte SS at baseline and decrease in 24-hour BP, neither systolic nor diastolic (P=0.66 and P = 0.84). Self-performed sodium reduction was feasible and led to decrease in 24-hour BP of 9/5 mm Hg compared with a control group. The erythrocyte SS did not correlate to the change in BP after lowering sodium intake. URL: https://clinicaltrials.gov; Unique Identifier: NCT05165823.

Assessment of Urinary Stone Chemical Compositions and Prevalence of Metabolic Disorders Among Urolithiasis Patients in Northern Sri Lanka: A Prospective Study.

Introduction Urolithiasis, a common urological disorder affecting the global population, demonstrates geographical diversity due to factors such as water quality, climate variations, health conditions, and dietary habits. This study, conducted in Northern Sri Lanka, examines urinary stone compositions and assesses the prevalence of metabolic disorders among urolithiasis patients. Methods This prospective cross-sectional study, conducted at Jaffna Teaching Hospital, Jaffna, Sri Lanka, from July 2022 to June 2023, focused on surgically treated urolithiasis patients. Institutional ethical clearance was obtained. Patient details and investigational findings were collected through questionnaires and data extraction forms. Stone analysis utilized Fourier transform infrared spectroscopy, and a detailed metabolic evaluation of a 24-hour urine collection sample was carried out. Results This study followed 153 surgically treated urolithiasis patients, primarily male (64.3%), with a mean age of 48.64. Ureteric colic (48.4%) was common, with kidney stones (45.8%) prevalent; 57.52% had recurrent stones. Diabetes mellitus (DM; 23.5%) was the top comorbidity. Calcium oxalate monohydrate (COM) stones (78.4%) were the most frequent, followed by uric acid (12.4%). COM predominated in the 40-59 age group. There was no significant gender-stone type association. A total of 86.9% had metabolic abnormalities, notably hypocitraturia (60.1%). Moreover, 23% had both hypocitraturia and hypomagnesuria. Some metabolic disorders showed gender differences, with a marginal age-metabolic disorder association (p < 0.061). Urine oxalate levels were normal, with higher variability in males. Conclusion Middle-aged males with urolithiasis commonly presented with ureteric colic and predominantly had COM stones. Recurrent stones were common, often accompanied by metabolic abnormalities such as hypocitraturia and hypomagnesuria, with DM as the primary comorbidity.

Using ChatGPT-4 to Analyze 24-Hour Urine Results and Generate Custom Dietary Recommendations for Nephrolithiasis.

Purpose: The increasing incidence of nephrolithiasis underscores the need for effective, accessible tools to aid urologists in preventing recurrence. Despite dietary modification's crucial role in prevention, targeted dietary counseling using 24-hour urine collections is underutilized. This study evaluates ChatGPT-4, a multimodal large language model, in analyzing urine collection results and providing custom dietary advice, exploring the potential for artificial intelligence-assisted analysis and counseling. Materials and Methods: Eleven unique prompts with synthesized 24-hour urine collection results were submitted to ChatGPT-4. The model was instructed to provide five dietary recommendations in response to the results. One prompt contained all "normal" values, with subsequent prompts introducing one abnormality each. Generated responses were assessed for accuracy, completeness, and appropriateness by two urologists, a nephrologist, and a clinical dietitian. Results: ChatGPT-4 achieved average scores of 5.2/6 for accuracy, 2.4/3 for completeness, and 2.6/3 for appropriateness. It correctly identified all "normal" values but had difficulty consistently detecting abnormalities and formulating appropriate recommendations. The model performed particularly poorly in response to calcium and citrate abnormalities and failed to address 3/10 abnormalities entirely. Conclusions: ChatGPT-4 exhibits potential in the dietary management of nephrolithiasis but requires further refinement for dependable performance. The model demonstrated the ability to generate personalized recommendations that were often accurate and complete but displayed inconsistencies in identifying and addressing urine abnormalities. Despite these limitations, with precise prompt design, physician oversight, and continued training, ChatGPT-4 can serve as a foundation for personalized medicine while also reducing administrative burden, indicating its promising role in improving the management of conditions such as nephrolithiasis.