Urinary Phosphorus Excretion Research Articles

Prediction models for phosphorus excretion of pigs.

The present study aimed to measure fecal and urinary phosphorus (P) excretion from pigs and to develop prediction models for P excretion of pigs. A total of 96 values for P excretions were obtained from pigs of 15 to 93 kg body weight (BW) fed 12 diets in four experiments and were used to develop the prediction models. All experimental diets contained exogenous phytase at 500 phytase units per kg. Body weight of pigs and dietary P concentrations were used as independent variables in the prediction models. The BW, feed intake, and P intake were positively correlated with total (fecal plus urinary) P excretions (r = 0.80, 0.91, and 0.94, respectively; p<0.001). The models for estimating P excretion were: fecal P excretion (g/d) = -0.654-0.000618×BW2+0.273×BW ×dietary P concentration (R2 = 0.83; p<0.001); urinary P excretion (g/d) = 0.045+ 0.00781×BW×dietary P concentration (R2 = 0.15; p<0.001); total P excretion (g/d) = -0.598-0.000613×BW2+0.280×BW×dietary P concentration (R2 = 0.86; p<0.001) where the BW of pigs and dietary P concentration are expressed as kg and % (as-fed basis), respectively. Based on the developed prediction models, the estimated annual fecal, urinary, and total P excretion for a market pig was 1.24, 0.09, and 1.33 kg/yr, respectively. The P excretions in market pigs can be estimated using BW of pigs and dietary P concentration. In the present model, a market pig excretes 1.24 kg of fecal P and 0.09 kg of urinary P per year.

Urinary Response to Consuming Plant-Based Meat Alternatives in Persons with Normal Kidney Function: The SWAP-MEAT Pilot Trial.

Consuming excess animal meat may exacerbate kidney disorders such as urinary stone disease and chronic kidney disease. Plant-based meat alternatives imitate animal meat, and replace animal with vegetable protein, but it is unclear whether eating plant-meat confers similar health benefits as eating whole vegetables. We hypothesized that eating plant-meat when compared with animal meat decreases dietary acid load but increases dietary phosphorus and nitrogen. SWAP-MEAT was a randomized eight-week, crossover trial (NCT03718988) of participants consuming >2 servings/day of either plant-meat or animal meat for each eight-week phase. We measured urine sulfate, ammonium, pH, phosphorus, urea nitrogen, citrate, and creatinine concentrations, and serum creatinine and bicarbonate concentrations from stored participant samples from each phase. At a single site, we enrolled 36 generally healthy participants (mean±SD age 50.2 ± 13.8 years, 67% women, and 69% White). Eating the plant-meat diet vs. eating the animal meat diet was associated with lower mean concentration of urine sulfate (-6.7 mEq/L; 95% CI -11.0, -2.4), urine ammonium (-4.2 mmol/L; 95% CI -8.2, -0.1), urine phosphorus (-9.0 mg/dL; 95% CI -17.5, -0.5), and urine urea nitrogen (-124.8 mg/dL; 95% CI -226.9, -22.6). Eating plant-meat compared with eating animal meat was associated with higher mean urine pH (+0.3 units; 95% CI 0.2, 0.5) and mean urine citrate/creatinine ratio (+111.65; 95% CI 52.69-170.60). After participants consumed a plant-meat diet compared with when they consumed an animal meat diet, mean serum creatinine concentration was lower (-0.07 mg/dL, 95% CI -0.10, -0.04), whereas mean serum bicarbonate concentration was not different. Eating plant-based meat products, compared with eating animal meat, was associated with lower urinary excretion of sulfate, ammonium, phosphorus, and urea nitrogen and higher urinary excretion of citrate. Our findings provide rationale for examining whether plant-based meat will benefit patients with kidney disease.

Glucocorticoid-induced acute diuresis in rats in relation to the reduced renal expression of sodium-dependent cotransporter genes

Although several studies have shown that glucocorticoids exert diuretic effects in animals and humans, the underlying mechanism responsible for the acute diuretic effect remains obscure. Here we examined the mechanism in terms of gene-expression. We observed that glucocorticoids, including dexamethasone (Dex) and prednisolone (PSL), acutely induced diuresis in rats in a dose-dependent manner. Free water clearance values were negative after Dex or PSL treatment, similar to those observed after treatment with osmotic diuretics (furosemide and acetazolamide). Dex significantly increased the urinary excretion of sodium, potassium, chloride, glucose, and inorganic phosphorus. Renal microarray analysis revealed that Dex significantly altered the renal expression of genes related to transmembrane transport activity. The mRNA levels of sodium/phosphate (NaPi-2a/Slc34a1, NaPi-2b/Slc34a2, and NaPi-2c/Slc34a3) and sodium/glucose cotransporters (Sglt2/Slc5a2) were significantly reduced in the Dex-treated kidney, being negatively correlated with the urinary excretion of their corresponding solutes. Dex did not affect renal expression of the natriuretic peptide receptor 1 (Npr1) gene, or the expression, localization, and phosphorylation of aquaporin-2 (AQP2), a water channel protein. These findings suggest that the acute diuretic effects of glucocorticoids might be mediated by reduced expression of sodium-dependent cotransporter genes.

Dietary Fiber Fermentability and Viscosity Impact Phosphorus Homeostasis and Urinary Phosphorus Excretion in a Rat Model of Chronic Kidney Disease

Dietary Fiber Fermentability and Viscosity Impact Phosphorus Homeostasis and Urinary Phosphorus Excretion in a Rat Model of Chronic Kidney Disease

Health-Related Quality of Life during 26-Week Intervention with the New Nordic Renal Diet.

The New Nordic Renal Diet (NNRD) is a whole-food approach, tailored to meet recommended guidelines in patients with moderate chronic kidney disease (stage 3b-4). The NNRD improved various metabolic and physiological endpoints during a 26-week randomized controlled study. Here, we examined the effect of dietary intervention on health-related quality of life (HRQoL). Sixty participants were recruited (NNRD group n = 30, control group n = 30) and 58 completed the study. During the intervention, the NNRD group received food boxes, and recipes once a week. The control group continued their habitual diet. HRQoL was examined at baseline and at the end of the intervention using the validated EuroQol-5D-5L, including a 5-point scale Likert questionnaire at the end of the intervention. Assessed by the EuroQol-5D-5L questionnaire, the NNRD group experienced a reduction in pain/discomfort during the intervention by 26% [-0.44 points (95% CI; -0.73, -0.16)], compared with no change in the control group [0.25 points (95% CI; -0.02, 0.53)] and a between-group difference of -0.70 points (95% CI; -1.03, -0.37, p < 0.001). A larger decrease of body fat mass was associated with a larger decrease in pain/discomfort (p = 0.014). In addition, the NNRD group reported an overall improvement in conducting usual daily activities by 23% [-0.30-point (95% CI; -0.50, -0.11)], while no change was seen in the control group [-0.02 points (95% CI; -0.21, 0.17)], with a between-group difference -0.28 points (95% CI; -0.51, -0.06, p = 0.014). A larger decrease in 24 h urine phosphorus excretion, used as a marker of compliance, was associated with a larger improvement in conducting usual daily activities (p = 0.036). The NNRD group had a clinically relevant improvement in various HRQoL outcomes.

#1496 High levels of sclerostin promote bone resorption and changes and mineral metabolism

Abstract Background and Aims The physiological function of sclerostin (SOST) remains unknown. It is known that SOST is produced in osteocytes and functions as an inhibitor of the Wnt/β-catenin pathway. Similarly, it is well-established that low levels of SOST lead to bone alterations affecting cortical bone, resulting in osteopetrosis and reduced calciuria. High levels of SOST are associated with osteoporosis. In this study, we aimed to investigate the impact of three elevated doses of SOST on cortical, trabecular, and subchondral bone, as well as its relationship with other parameters of mineral metabolism. Method Bone histomorphometry, mCT, immunohistochemistry, and analysis of mineral metabolism parameters revealed that high doses of SOST over a 14-day period led to a reduction in trabecular bone volume due to a significant increase in bone resorption through the direct activation of osteoclastogenesis. Results Bone resorption, as measured by TRAP activity, was higher in trabecular, cortical, and subchondral bone. Similarly, high doses of SOST increased the number of hypertrophic chondrocytes, consequently expanding the growth plate area. Cortically, positive TRAP staining was observed, suggesting osteocytic osteolysis and trabecularization of cortical bone. The increased bone resorption resulted in a substantial rise in urinary excretion of phosphorus and calcium, accompanied by elevated levels of FGF23 and a significant decrease in PTH. Conclusion The findings suggest that elevated levels of SOST promote bone resorption through the activation of osteoclasts and the generation of osteocytic osteolysis. The increase in calcium and phosphorus levels led to changes in mineral metabolism, indicating a close relationship between SOST and other mineral metabolism parameters.

#1610 FGF23-mediated hypertension via augmented calcium entry in vascular smooth muscle cells

Abstract Background and Objectives Ongoing studies are shedding light on the potential connection between FGF23 and hypertension. In experimental settings, the administration of recombinant FGF23 in mice has been demonstrated to induce hypertension by elevating serum sodium, along with an increase in NCC receptors in the kidney. Clinical evidences further supports pro-hypertensive effects of high circulating levels of FGF23. Our group has previously demonstrated a direct influence of FGF23 on increased arterial stiffness by inducing a phenotypic transition in vascular smooth muscle cells (VSMCs) from a contractile to a synthetic phenotype. This study aimed comprehensively to evaluate, both in vivo and in vitro, whether FGF23 directly leads to hypertension through the stimulation of intracellular calcium entry in vascular cells. Methods To ascertain whether FGF23 contributes to hypertension through a direct impact on blood vessels, recombinant FGF23 (15 µg/day) was administered for 28 days via Alzet pumps. Blood pressure was meticulously measured in these animals, and we investigated alterations in vascular remodeling and calcium channels, as well as proteins associated with vascular contraction such as Orai1, STIM1, PKD1, SERCA2a, and AGTR1. In vitro experiments included the evaluation of the effect of elevated levels of recombinant FGF23 (2 ng/ml) over 9 days on intracellular calcium entry stimulated by Ang2 (100 nM) or Thapsigargin (2.5 µM). We used the FURA method to conduct these experiments. To elucidate the in vitro pro-hypertensive mechanisms of FGF23, studies were conducted with the administration of inhibitors targeting FGF Receptors 1-3 (AZD4547, 150 nM), FGF Receptor-4 (BLU9931, 10 nM), and Erk1/2 phosphorylation (PD98059, 10 μM). Additionally, changes in Orai1, STIM1, PKD1, SERCA2a, and AGTR1 were also evaluated in these VSMCs. Results After 28 days of recombinant FGF23 treatment, no significant differences were observed in serum sodium levels, yet there was a marked increase in urinary phosphorus excretion. Systolic and diastolic blood pressure values showed a progressive significant elevation in animals exposed to high levels of FGF23. The expression of AGTR1 and PKD1 levels significantly increased after FGF23 administration for 28 days (Figure). However, Orai1 and STIM1 in the thoracic aorta exhibited no significant differences following FGF23 treatment. In VSMCs, the exposure to recombinant FGF23 for 9 days resulted in increased calcium entry upon Ang2 stimulation (Figure). This effect was markedly diminished after inhibiting FGFR1-3 receptors and Erk1/2 phosphorylation (Figure). Notably, the inhibition of FGF23 receptor 4 (FGFR4) had no impact on the calcium entry induced by FGF23 (Figure). While Orai1, STIM1, IP3R, and TRPV5 in VSMCs remained unaffected by recombinant FGF23 administration, PKD1, SERCA2, and AGTR1 levels were significantly elevated compared to control cells (Figure). The addition of Thapsigargin in a Ca2+-free culture medium to VSMCs incubated with recombinant FGF23 for 9 days led to increased Ca2+ efflux from endoplasmic reticulum. Conclusion Elevated levels of FGF23 directly enhanced calcium entry in VSMCs. This effect is mediated by FGFR1-3 receptors, Erk1/2 phosphorylation, and the upregulation of related protein to cell contraction such as SERCA2a, PKD1 or AGTR1. These modifications could be responsible of FGF23-associated hypertension in the experimental model.

Reference values of parathyroid hormone in very low birth weight infants.

The primary goal was to estimate reference values of parathyroid hormone (PTH) in very low birth weight infants without severe neonatal morbidity. A secondary objective was to assess the relationship between PTH serum levels and selected laboratory markers of bone metabolism. Ninety two infants with birth weight less than 1500g met the inclusion criteria of the study. Serum levels of PTH, 25-hydroxyvitamin-D [25(OH)D], C3-epi-25(OH)D, total calcium, phosphorus, and alkaline phosphatase, and urinary levels of calcium, phosphorus, and creatinine were examined on day 14 and subsequently every 2weeks until discharge. Of the total 167 serum samples examined for PTH levels in infants without 25(OH)D deficiency the estimated range was 0.9-11.9 pmol/l (8.5-112.3 pg/mL). During the first month, no statistically significant correlation was observed between PTH level and that of 25(OH)D, C3-epimers of 25(OH)D, S-Ca, S-P, or ALP, nor with urinary excretion of calcium and phosphorus. From the second month of life, there was a moderately significant correlation between PTH and 25(OH)D (Rho = -0.40, P =< .001), between PTH and calcium/creatinine ratio (Rho = -0.56, P = < .001), and between PTH and phosphorus/creatinine ratio (Rho = 0.51, P = < .001). The physiological range for PTH levels for preterm neonates without 25(OH)D deficiency was estimated as 0.9-11.9 pmol/l (8.5-112.3 pg/mL). It seems that elevation of serum PTH above this range can be considered as hyperparathyroidism in very low birth weight infants.

Post-intervention Adherence to the New Nordic Renal Diet among patients with chronic kidney disease, stages 3 and 4.

The New Nordic Renal Diet (NNRD) is a meal pattern reduced in phosphorus, protein, and sodium for patients with moderate chronic kidney disease. The NNRD showed improvements in metabolic, and physiological outcomes after 26-weeks intervention. In the original study, participants were randomized to NNRD (n = 30), or control (habitual diet) (n = 30). The aim of this study was to explore adherence to the NNRD 3 months after cessation of intervention (follow-up). Fifty-seven participants completed the follow-up visit, which consisted of fasting blood samples and 24 h urine samples. At follow-up, there was no longer a significant reduction in 24 h urine phosphorus excretion in the NNRD group. From intervention to follow-up, 24 h urine phosphorus increased by 63 mg in the NNRD group, vs. -24.1 mg in the control group, between-group difference 87.1 mg (-10.1, 184.3, p = 0.08). Our findings show that more active intervention is needed to support adherence and maintain beneficial effects of the NNRD.

PSXI-17 Prediction Models for Phosphorus Excretion of Pigs

Abstract The objective of the present study was to develop prediction equations for daily phosphorus excretion based on body weight (BW) and dietary phosphorus concentration of pigs. Four experiments were conducted using pigs with an initial body weight of 15 kg, 30 kg, 50 kg, and 78 kg. In the experiment 1, the experimental diets were mainly based on corn, soybean meal, whey powder, fish meal, and blood plasma. In the experiments 2, 3, and 4, the diets based on corn, soybean meal, and fibrous ingredients were formulated. All experimental diets were supplemented with commercial phytase at 500 FTU/kg. In all experiments, a total collection method and the marker-to-marker procedure were used for fecal and urinary collection. Fecal and urinary phosphorus excretions were determined. Correlation coefficients among BW, daily phosphorus intake, and daily phosphorus excretion of pigs were determined. Prediction equations for phosphorus excretion were developed using BW and dietary phosphorus concentration as independent variables. The BW had positive correlations with fecal and total phosphorus excretion (r = 0.78 and P &amp;lt; 0.001 for fecal phosphorus excretion and r = 0.78 and P &amp;lt; 0.001 for total phosphorus excretion). The prediction equations for predicting fecal phosphorus excretion and total phosphorus excretion were: fecal phosphorus excretion (g·pig–1·d–1) = –0.647 – 0.00065 × BW2 + 0.270 × BW × dietary phosphorus concentration (R2 = 0.81; P &amp;lt; 0.001); total phosphorus excretion (g·pig–1·d–1) = –0.619 – 0.00064 × BW2 + 0.277 × BW × dietary phosphorus concentration (R2 = 0.85; P &amp;lt; 0.001) where BW in kg and phosphorus concentration in %. The BW of pigs corresponding to the age was predicted using the NRC model. The mean phosphorus excretion of pigs weighing from 7 kg to 120 kg at day 22 to 180 was calculated using a developed estimation equation, with BW and total phosphorus requirement used as independent variables. Daily fecal and total phosphorus excretions were 3.77 g·pig–1·d–1 and 4.01 g·pig–1·d–1, respectively.

Health effects of the New Nordic Renal Diet in patients with stage 3 and 4 chronic kidney disease, compared with habitual diet: a randomized trial

BackgroundChronic kidney disease (CKD) leads to an accumulation of waste products and causes adverse cardiometabolic effects. ObjectivesWe investigated the health effects of the New Nordic Renal Diet (NNRD), a novel meal pattern reduced in phosphorus, protein, and sodium. MethodsA 26-wk randomized trial compared the NNRD with a habitual diet. The NNRD group received weekly home deliveries of food and recipes. Monthly study visits included fasting blood samples, 24-h urine samples, blood pressure, and anthropometric measurements. Intention-to-treat analysis used linear mixed-effects models. ResultsSixty patients, mean estimated glomerular filtration rate (eGFR) 34 mL/min/1.73 m2 and body mass index of 25–27 kg/m2, were included and 58 completed. Metabolic syndrome was present in 53% (NNRD group) and 57% (control group). The NNRD group (n = 30) reduced their 24-h urine phosphorus excretion by 19% (−153 mg; 95% confidence interval [CI]: −210, −95), control group (n = 30) (no change), between-group difference −171 mg (95% CI: −233, −109; P < 0.001). Proteinuria was reduced by 39% in the NNRD group (−0.33 g/d; 95% CI: −0.47, −0.18), control group (no change), between-group difference −0.34 g/d (95% CI: −0.52, −0.17; P < 0.001). Plasma urea was reduced by −1.5 mmol/L in the NNRD group (95% CI: −2.1, −0.9), control group (no change), between-group difference −1.4 mmol/L (95% CI: −2.0, −0.7; P < 0.001). Systolic blood pressure fell by −5.2 mmHg in the NNRD group (95% CI: −8.4, −2.1), control group (no change), between-group difference −3.9 mmHg (95% CI; −7.6, −0.2; P = 0.04). The NNRD group lost −1.7 kg (95% CI: −2.6, −0.8), control group (no change), between-group difference −2.0 kg (95% CI: −3.0, −1.0; P < 0.001). There were no effects on eGFR during the 26-wk intervention. ConclusionNNRD in moderate CKD reduces phosphorus excretion, proteinuria, systolic blood pressure, and weight, mainly by reducing abdominal fat.This trial was registered at clinicaltrials.gov as NCT04579315.

#2971 LONG-TERM EFFECTS OF THE NEW NORDIC RENAL DIET ON PHOSPHOROUS HOMEOSTASIS IN PATIENTS WITH CHRONIC KIDNEY DISEASE STAGE 3 AND 4

Abstract Background and Aims Chronic kidney disease (CKD) causes severe disturbances in phosphate metabolism. The New Nordic Renal Diet (NNRD) is a whole food approach designed by our group, with low dietary phosphorus content (850 mg/day). In a 1-week study, NNRD had positive effects on phosphorus homeostasis in patients with CKD stage 3-4 [1]. The aim of the present study was to examine the long-term health effects of a dietary intervention with NNRD in patients with CKD stage 3-4 [2]. Method A 26-week randomized, controlled, non-blinded trial comparing the effect of NNRD vs. non-restricted habitual diet. Patients in the NNRD group received weekly home delivery of fresh food items (free of charge) and recipes for five days of the week, and on the remaining two days they were instructed to prepare meals according to the NNRD food principles. The study was designed with seven follow-up visits in the outpatient clinic where fasting blood samples and 24-hour urine collection were delivered. Linear mixed-effects models were used to assess the effects of the intervention, time, and the potential interaction between intervention and time. The primary endpoint was the difference in 24-hour urine phosphorus excretion between the two study groups. Secondary endpoints included fractional phosphorus excretion and plasma fibroblast growth factor 23 (p-FGF23). Results Sixty patients (mean age 54 years, 31 women) with mean eGFR of 34 ml/min/1.73 m2 were included. Two patients were withdrawn due to dialysis initiation. In the NNRD-group (n = 29), mean 24-hour urine phosphorus excretion during the intervention period was 651 mg (SD, 35 mg) vs. 930 mg (SD, 84 mg) in the control group (n = 29), between-group difference 279 (95% CI; -372, -91; P &amp;lt; 0.001) (Figure 1). Mean fractional phosphorus excretion was 11% (SD, 5%) in the NNRD-group and 14% (SD, 7%) in the control group, between-group difference 3% (95% CI; -6.4, -0.8; P = 0.01). Mean p-FGF23 was 162 pg/ml (SD, 130 pg/ml) in the NNRD-group and 215 pg/ml (SD, 230 pg/ml) in the control group, between-group difference 52 pg/ml (95% CI; -100, 73; P = 0.03). P-urea was 3.4 mmol/L lower in the NNRD group (95% CI; -5.3, -0.2, P = 0.03). P-albumin was 1.1 g/L higher in the NNRD group (95% CI; 0.02, 2.4; P = 0.04) and 24-h urine bicarbonate excretion was 4.1 mmol higher in the NNRD group (95% CI; 0.7, 7.5, P = 0.01). There was no difference between study groups in p-phosphorous, p-creatinine, p-potassium, p-calcium, p-lipids, or proteinuria. Conclusion NNRD intervention in the context of fresh food delivery and recipes was feasible and had a major beneficial effect on phosphorous parameters in patients with CKD 3-4.

A Phase I Randomized Trial of Once-Daily Versus Twice-Daily Recombinant Human Parathyroid Hormone (1-84) for Hypoparathyroidism.

Recombinant human parathyroid hormone (1-84), rhPTH(1-84), is an approved adjunctive treatment to oral calcium and active vitamin D for adult patients with hypoparathyroidism; however, there is limited information on the effect of twice daily (BID) dosing of rhPTH(1-84). This was a phase I, open-label, randomized, crossover, multicenter study conducted in adult patients with chronic hypoparathyroidism. The primary objective was to assess the pharmacokinetic profile and pharmacodynamic effects of 1 day of treatment with rhPTH(1-84) administered subcutaneously at 25 μg BID, 50 μg BID, and 100 μg once daily (QD) with or without supplemental oral calcium. Safety and tolerability were evaluated as secondary objectives. In total, 33 patients with chronic hypoparathyroidism completed the study. Treatment with rhPTH(1-84), both BID and QD, over the short-term maintained serum calcium, lowered serum phosphorus, decreased urinary calcium excretion, and increased urinary phosphorus excretion. The decrease in urinary calcium excretion was numerically greater for BID than QD. Generally, baseline-adjusted pharmacokinetic parameters including area under the curve and maximum observed concentration increased with increasing rhPTH(1-84) dose, although this effect was not dose proportional. No new safety findings were observed. Our study revealed no differences thought to be clinically meaningful in pharmacokinetic or pharmacodynamic parameters with BID versus QD rhPTH(1-84) dosing. Future long-term studies are warranted to further elucidate the effects of alternative dosing strategies. © 2023 Takeda Development Center Americas, Inc and The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Urinary Phosphorus Excretion and Cardiovascular Outcomes in Patients with Pre-Dialysis Chronic Kidney Disease: The KNOW-CKD Study.

The relationship between 24-h urinary phosphorus excretion (24 h UPE) and cardiovascular disease in patients with pre-dialysis chronic kidney disease (CKD) has rarely been studied, despite the fact that the relationship between serum phosphorus level and the risk of a cardiovascular event is well established. A total of 1701 patients with pre-dialysis CKD were finally included for the analyses and were divided into tertiles by 24 h UPE (first tertile (T1, 349.557 (mean) ± 88.413 (standard deviation)), second tertile (T2, 557.530 ± 50.738), and third tertile (T3, 851.695 ± 171.593). The study outcome was a six-point major adverse cardiac event (MACE). The median follow-up duration was 7.992 years. Kaplan-Meier curve analysis visualized that the cumulative incidences of a six-point MACE (p = 0.029) significantly differed from 24 h UPE levels, as the incidence rate of the study outcomes was highest in T1 and lowest in T3. Cox proportional hazard models unveiled that, compared to T1, the risk of a six-point MACE was significantly decreased in T3 (adjusted hazard ratio (HR) 0.376, 95% confidence interval (CI) 0.207 to 0.683). The restricted cubic spline curve analysis visualized an inverted S-shaped association between 24 h UPE level and the risk of a six-point MACE, indicating a significantly increased risk of a six-point MACE in patients with a low 24 h UPE level. In conclusion, low 24 h UPE is associated with adverse cardiovascular outcomes in patients with CKD. Our finding emphasizes that low 24 h UPE should not be a reliable marker for dietary restriction of phosphorus that essentially leads to better outcomes in patients with CKD.

Increasing Phosphorus Intake Reduces Urinary Concentrations of Magnesium and Calcium in Adult Ovariectomized Cats Fed Purified Diets

We assessed the phosphorus requirement of adult cats and the relationship between phosphorus intake and the fecal and urinary excretion of calcium, magnesium and phosphorus. Female cats (ovariectomized at the onset of sexual maturity) were fed purified diets containing 4.6, 9.2, 18.4 or 27.7 mmol phosphorus/MJ in a 4 × 4-wk crossover study. During the experiment, balance studies were performed and blood samples were taken. A dietary level of 4.6 mmol phosphorus/MJ was found to be sufficient to maintain phosphorus balance and normal plasma concentrations of phosphorus in the adult ovariectomized cats. Increasing levels of dietary phosphorus in the form of NaH2PO4·2H2O caused lower urinary pH values, lower urinary concentrations of calcium and magnesium, and higher urinary concentrations of phosphorus. When dietary levels of phosphorus were raised, the percentage of apparent absorption of magnesium was lower, whereas that of phosphorus was higher. Although it could be predicted that dietary phosphorus levels higher than the National Research Council recommendation of 9.2 mmol/MJ markedly reduced urinary struvite saturation, these higher levels are discouraged because they are associated with lower plasma phosphorus concentrations and creatinine clearance.

A rare case of concomitant hypophosphatemic osteomalacia and neurofibromatosis type 1

Abstract Introduction Neurofibromatosis type 1 is a rare genetic disorder with an increased susceptibility to develop skeletal abnormalities. However, the association of hypophosphatemic osteomalacia and neurofibromatosis type 1 is extremely rare. Herein, we report a case of hypophosphatemic osteomalacia in concomitant with neurofibromatosis type 1. Clinical Case A 45-year-old Turkish female patient, who was followed up in another hospital due to osteoporosis and kyphoscoliosis, applied to us with the complaints of persistent bone pain and inability to walk. She had no chronic diseases other than osteoporosis. The physical examination revealed widespread freckling over her trunk and proximal parts of upper and lower extremities and multiple neurofibromas and cafe au lait spots all over her body (figure 1). It was learned that her 2 brothers, mother and daughter also had the widespread freckling. They have no known chronic diseases. She had a severe degree of kyphoscoliosis. She had not have any complaints up to 24 years of age, and low back pain started after delivery. She was diagnosed with osteoporosis at the age of 29. In about 15 years, her height decreased from 167 cm to 135 cm. She had a severe degree of kyphoscoliosis and severe bone pain and was unable to walk on her own because of pain. Bilateral ophthalmic examination revealed no Lisch nodules. Audiometer revealed no abnormalities. Laboratory findings were as follows: Ca: 9.4 (8.4–10.6 mg/dl), phosphorus: 1.8 (2.3–4.7 mg/dl), albumin: 4.2 g/dl, parathormone: 88.3 (11–80 pg/ml), 25 hydroxy vitamin D: 26.1 ug/L, creatinine: 0.4 mg/dl, alkaline phosphatase: 79 (35–105 U/L), the 24-hour urinary excretion of calcium: 187.5 mg/24 h, the 24-hour urinary excretion of phosphorus: 253 mg/24 h, fractional excretion of phosphate: %8.5 and maximum transport of phosphorus in the renal proximal tubules (TmP/GFR): 0.74 (0.88–1.42 mmol/L). According to laboratory data there was a hyperphosphaturia. On the basis of the physical examination, laboratory and radiological findings, she was diagnosed with neurofibromatosis type 1 and hypophosphatemic osteomalacia. Oral phosphate solution (1.5 gram as elemantary phosphorus per day in 3 divided doses) and calcitriol (1 microgram per day in 2 divided doses) were started. After 6 months of therapy, bone pain was significantly decreased and her serum phosphorus level increased. The results of genetic analysis are awaited. Conclusion The coexistence of hypophosphatemic osteomalacia and neurofibromatosis type 1 have been reported in less than 50 cases in the literature. The underlying mechanism is not clarified. The diagnosis of hypophosphatemic osteomalacia should be kept in mind in patients with neurofibromatosis type 1, as they will benefit greatly from oral phosphorus solution and active vitamin D.

Changes and Influencing Factors of Urinary Phosphorus Excretion in Patients with Different Stages of Chronic Kidney Disease.

The aim of the study was to explore the changes and the possible influencing factors of phosphorus excretion in chronic kidney disease (CKD) patients. A database with 204 patients who met the CKD diagnostic criteria was established. Clinical data, including 24-hour urine phosphorus excretion (24-hour UPE), were collected. The demographic and clinical characteristics of CKD patients in different stages and the changes in serum phosphorus (P) and 24-hour UPE with renal function were studied. After exploring the factors influencing 24-hour UPE by multiple linear regression analysis, the effects of gender on 24-hour UPE was assessed. Among 204 patients, there were significant differences in serum calcium (Ca), P, 24-hour UPE, intact parathyroid hormone (iPTH), and 25-hydroxyvitamin D [25(OH)-VD] among different CKD stages. Twenty-four-hour UPE fluctuated greatly, but serum P was relatively stable, which was > 1.46 mmol/L at an estimated glomerular filtration rate (eGFR) < 10 mL/minute/1.73 m2. Male gender (β = 3.42, p < 0.00) and eGFR (β = 0.06, p < 0.00) were related to 24-hour UPE, while age, body weight, albumin (ALB), iPTH, and serum P were not related to 24-hour UPE according to regression analysis. There were significant differences in 24-hour UPE and serum P between males and females. Urinary phosphorus excretion decreased with decreasing renal function in CKD patients. Urinary phosphorus excretion might be affected by eGFR and gender.

Tubular calcium, magnesium, and phosphate excretion during therapeutic hypothermia for neonatal hypoxic–ischemic encephalopathy: A prospective study

ObjectivesHypocalcemia, hypomagnesemia, and hyperphosphatemia are common electrolyte disturbances in perinatal asphyxia (PA). Different reasons have been proposed for these electrolyte disturbances. This study investigated the effect of the urinary excretion of calcium (Ca), magnesium (Mg), and phosphorus (P) on the serum levels of these substances in babies who were treated using therapeutic hypothermia for hypoxic ischemic encephalopathy (HIE) caused by PA. This study sheds light on the pathophysiology that may cause changes in the serum values of these electrolytes. MethodsThis study included 21 healthy newborns (control group) and 38 patients (HIE group) who had undergone therapeutic hypothermia due to HIE. Only infants with a gestational age of 36 weeks and above and a birth weight of 2000 g and above were evaluated. The urine and serum Ca, Mg, P, and creatinine levels of all infants were evaluated at 24, 48, and 72 h. ResultsThe lower serum Ca value and the higher serum P value of the HIE group were found to be statistically significant compared to the control group (p<0.05). There was no significant difference in serum Mg values between the groups. However, hypomagnesemia was detected in five patients from the HIE group. The urine excretion of FeCa and FeMg at 24 h, and FeP excretion at 48 and 72 h were found to be significantly higher in the HIE group compared to the control group. ConclusionsThis study determined that the urinary excretion of Ca, Mg, and P has an effect on the serum Ca, Mg, and P levels of infants with HIE.

Estimation of phosphorus requirements of sows based on 24-h urinary phosphorus excretion during gestation and lactation.

Phosphorus requirements of reproducing sows were estimated using 24-h urinary P excretion. Thirty-six multiparous sows were fed one of six maize-soybean meal-based diets with total P ranging from 0·40 to 0·80 % in 0·08 % increments with a constant Ca:total P ratio (1·25:1). Diets were fed from day 7·5 ± 1 after breeding until the end of lactation (day 26 ± 1). Urine samples were collected in mid and late gestation (days 77·1 ± 2 and 112·4 ± 1) and early and late lactation (days 4·5 ± 1 and 18·2 ± 1). Phosphorus requirements were estimated using linear and nonlinear regression models. Based on a single 24-h urinary P excretion, estimated daily dietary total P requirements in mid and late gestation were 10·3 g (6·0 g standardised total tract digestible P, STTD P), and estimates for early and late lactation were 31·1 g (16·6 g STTD P) and 40·3 g (22·1 g STTD P), respectively. Plasma P and Ca concentrations were maintained within normal ranges at the estimated levels of P requirements. No differences among treatments were observed for plasma parathyroid hormone (P ≥ 0·06) and bone formation marker (P ≥ 0·16). In lactation, bone resorption marker decreased (P ≤ 0·001) as sows consumed more P. Among the analysed variables, urinary P was the most sensitive response to changes in dietary P intake. Urinary P excretion offers a practical method to estimate P requirements in sows. Our recommended daily total P requirements are 10·3 g for gestation and 35·7 g for lactation.

Association of urinary sodium excretion with fluid overload in patients with chronic kidney disease

Objective: To investigate the relationship between urinary sodium excretion and fluid overload (FO) in non-dialysis patients with chronic kidney disease (CKD). Methods: Patients with CKD stage 1-4 who underwent bioelectrical impedance (BIA) in the Department of Nephrology, Jiangsu Province Hospital from December 2019 to January 2021 were recruited. All enrolled patients were categorized into two groups according to whether or not they develop FO. Further, clinical parameters were compared between the two groups. Spearman correlation analysis was used to investigate the association between over hydration/extracellular water (OH/ECW) and clinical characteristics. Multivariate logistic regression analysis was performed to evaluate the relationship between urinary sodium excretion and FO (FO was defined as OH/ECW≥7%). Results: A total of 385 patients with CKD stage 1-4 were finally included in the study, with a mean age of (46±15) years. There were 216 male cases (56.1%), and 150 cases (39.0%) existed FO. Spearman correlation analysis indicated that OH/ECW positively correlated with urinary sodium excretion (r=0.147, P=0.004), urinary protein excretion (r=0.555, P<0.001) and systolic blood pressure (r=0.241, P<0.001), but inversely related to estimated glomerular filtration rate (eGFR) (r=-0.111, P=0.030) and serum albumin (r=-0.659, P<0.001). After adjusting for confounding factors including age, systolic blood pressure, diabetes, urinary protein excretion, serum albumin, serum sodium, serum chlorine, urinary calcium excretion, urinary phosphorus excretion and use of diuretics, multivariate logistic regression analysis demonstrated that higher level of urinary sodium excretion was associated with increased risk of FO in patients with CKD (OR=1.005, 95%CI: 1.000-1.011, P=0.048). Conclusion: High urinary sodium excretion is independently associated with fluid FO in non-dialysis patients with CKD.