24-hour Urinary Creatinine Research Articles

Correlation of 24-Hour Blood Pressure and Heart Rate Variability to Renal Function Parameters in Hypertensive Patients. The Effect of Smoking.

Intrarenal hemodynamics depend on blood pressure (BP), heart rate (HR), and smoking. Although BP levels have been associated with kidney function, the effect of HR levels, BP, and HR variability on renal function are less well clarified. This cross-sectional study sought to determine the association of 24-hour BP and HR variability with kidney function in hypertensive patients, stratified by smoking. The study comprised 9600 nondiabetic, never-treated hypertensive individuals without evident renal impairment examined from 1985 to 2014 (aged 53.3±13.4years, 55.3% males). The 24-hour systolic BP (SBP) and HR variability were estimated via their coefficient of variation (CV =standard deviation×100/mean value) derived from ambulatory recording. The CV SBP-to-CV HR ratio (CV R) was used as a marker of the interplay between 24-hour SBP and HR variability. Renal function was estimated via 24-hour urine creatinine clearance (CrCl), estimated glomerular filtration rate (eGFR), albumin-to-creatinine ratio (ACR), and 24-hour urine α1 -microglobulin. After adjustment for age, sex, and smoking, CV SBP wasfound to be weakly correlated to eGFR (r=-0.017, P=.1) and somewhat more strongly to CrCl, ACR, and α1 -microglobulin (r=-0.032, 0.072, and 0.065; P=.002, <.001 and <.001, respectively). CV HR was much better related to renal function, with stronger adjusted correlations to CrCl, eGFR, ACR, and α1 -microglobulin (r=0.185, 0.134, -0.306, -0.247; all P<.001, respectively). CV R also showed equally good adjusted correlations (r=-0.175, -0.125, 0.336, 0.262; all P<.001, respectively). Most adjusted correlations for CV HR and CV R were even better in smokers (r=0.213, 0.158, -0.332, -0.272 and -0.183, -0.118, 0.351, 0.275, respectively; all P<.001). CV HR and CV R emerge as better related to kidney function than CV SBP, especially in smokers. The correlation of CV HR and CV SBP to renal function is inverse to each other. ACR and α1 -microglobulin are better related to variability indices than CrCl and eGFR. However, causal relations cannot be proved.

The Efficacy of Serum Cystatin C and Creatinine to Diagnose Impaired Renal Function in Cancer Patients Under Treatment with Cisplatin

Renal function can be impaired in cancer patients treated with cisplatin. Currently, serum creatinine is used to diagnose renal dysfunction. This study aims to determine the efficacy of serum cyatatin C and ceratinine in contrast to the 24-hour urine creatinine clearance [CrCl] as the gold standard method in diagnosis of renal dysfunction in cancer patients under treatment with cisplatin. Seventy patients under treatment with cisplatin included. Serum cystatin C and creatinine were measured. CrCl in 24-hour urine was calculated. Measurements were done two times; before initiation of chemotherapy and before the fourth cycle of the chemotherapy. Then, using Receive Operating Curve [ROC] curve and at different cut-off points, sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV] of both cystatin C and creatinine to detect renal dysfunction were calculated. 24-hour urine CrCl was the gold standard method to define renal dysfunction. Sensitivity and specificity values of cystatin C of > 1.28 mg/L to predict CrCl< 78 mL/min were 77% and 95%, respectively. PPV and NPV of cystatin C were 95% and 79%, respectively with a diagnostic accuracy of 86%. On the other hand, sensitivity and specificity of creatinine were 64% and 47%, respectively. Serum cystatin C concentration had better sensitivity, specificity, PPV, and NPV compared to creatinine in detection of early stages of renal dysfunction in cancer patients under treatment with cisplatin. This marker can be used as an effective screening method in such patients to find renal dysfunction at its early stages.

Abstract P168: The Relationship of Urinary Sodium and Potassium Excretion with Left Ventricular Structure and Function in Patients with Chronic Kidney Disease: Prospective Analyses from the Chronic Renal Insufficiency Cohort Study

Introduction: Patients with chronic kidney disease (CKD) are at an increased risk of CVD compared to the general population. Left ventricular hypertrophy (LVH) is an independent risk factor for CVD in the general population and in CKD patients. In the general population, sodium (Na) excretion is directly associated with LVH. However, this association has not been examined in patients with CKD. Hypothesis: We hypothesized that in CKD patients, urinary Na excretion would be directly and urinary potassium (K) would be indirectly associated with development of ejection fraction (EF) &lt; 50% and LVH and longitudinal changes in EF and left ventricular mass index (LVMI). Methods: The Chronic Renal Insufficiency Cohort Study (CRIC) is a prospective cohort study of 3,939 participants with CKD. Dietary Na and K excretion were assessed by averaging three 24-hour urinary measures (over 2 years) and calibrated to sex-specific mean 24-hour urinary creatinine excretion. Echocardiograms (ECHO) were conducted at follow-up years 1, 4, and 7 and centrally analyzed to quantify EF and LVMI. LVH is defined as LVMI ≥ 47 g/m 2.7 in women and LVMI ≥ 50 g/m 2.7 in men. Log-linear binomial and linear mixed effects models were used. Results: During follow-up, 676 participants developed EF &lt;50% and 238 developed LVH among those with EF ≥ 50% or free of LVH at the first ECHO, respectively. After multivariate adjustment, participants in the highest quartile of adjusted sodium excretion (&gt;196.2 mmol/24 hours) had a relative risk of 1.31 (95% CI 1.08, 1.59) of developing an EF &lt; 50% during follow-up compared to those in the lowest quartile (&lt;127.8 mmol/24 hours). Furthermore, participants in the highest quartile of adjusted urinary sodium excretion had a greater annual decrease in ejection fraction (-1.36%, 95 CI: -1.53, -1.19%) compared to those in the lowest quartile (-0.95%, 95% CI: -1.11, -0.79%; p for trend across quartiles 0.0003). No significant association was observed between K excretion and development of EF &lt; 50% or change in EF. In addition, no association was observed between adjusted Na or K excretion and development of LVH or change in LVMI during follow-up. Conclusions: Higher Na excretion is associated with a greater likelihood of developing an EF &lt;50% and a greater annual decrease in EF. Further studies are needed to determine if interventions to reduce high dietary sodium could slow the decline in left ventricular structure and function in patients with CKD.

New anthropometry-based age- and sex-specific reference values for urinary 24-hour creatinine excretion based on the adult Swiss population.

BackgroundUrinary creatinine excretion is used as a marker of completeness of timed urine collections, which are a keystone of several metabolic evaluations in clinical investigations and epidemiological surveys.The current reference values for 24-hour urinary creatinine excretion rely on observations performed in the 1960s and 1970s in relatively small and mostly selected groups, and may thus poorly fit to the present-day general European population.The aim of this study was to establish and validate anthropometry-based age- and sex-specific reference values of the 24-hour urinary creatinine excretion on adult populations with preserved renal function.MethodsWe used data from two independent Swiss cross-sectional population-based studies with standardised 24-hour urinary collection and measured anthropometric variables. Only data from adults of European descent, with estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m2 and reported completeness of the urinary collection were retained. A linear regression model was developed to predict centiles of the 24-hour urinary creatinine excretion in 1,137 participants from the Swiss Survey on Salt and validated in 994 participants from the Swiss Kidney Project on Genes in Hypertension.ResultsThe mean urinary creatinine excretion was 193 ± 41 μmol/kg/24 hours in men and 151 ± 38 μmol/kg/24 hours in women in the Swiss Survey on Salt. The values were inversely correlated with age and body mass index (BMI).Based on current reference values (177 to 221 μmol/kg/24 hours in men and 133 to 177 μmol/kg/24 hours in women), 56% of the urinary collections in the whole population and 67% in people >60 years old would have been considered as inaccurate.A linear regression model with sex, BMI and age as predictor variables was found to provide the best prediction of the observed values and showed a good fit when applied to the validation population.ConclusionsWe propose a validated prediction equation for 24-hour urinary creatinine excretion in the general European population, based on readily available variables such as age, sex and BMI, and a few derived normograms to ease its clinical application. This should help healthcare providers to interpret the completeness of a 24-hour urine collection in daily clinical practice and in epidemiological population studies.

Decrease in urinary creatinine excretion in early stage chronic kidney disease.

BackgroundLittle is known about muscle mass loss in early stage chronic kidney disease (CKD). We used 24-hour urinary creatinine excretion rate to assess determinants of muscle mass and its evolution with kidney function decline. We also described the range of urinary creatinine concentration in this population.MethodsWe included 1072 men and 537 women with non-dialysis CKD stages 1 to 5, all of them with repeated measurements of glomerular filtration rate (mGFR) by 51Cr-EDTA renal clearance and several nutritional markers. In those with stage 1 to 4 at baseline, we used a mixed model to study factors associated with urinary creatinine excretion rate and its change over time.ResultsBaseline mean urinary creatinine excretion decreased from 15.3±3.1 to 12.1±3.3 mmol/24 h (0.20±0.03 to 0.15±0.04 mmol/kg/24 h) in men, with mGFR falling from ≥60 to <15 mL/min/1.73 m2, and from 9.6±1.9 to 7.6±2.5 (0.16±0.03 to 0.12±0.03) in women. In addition to mGFR, an older age, diabetes, and lower levels of body mass index, proteinuria, and protein intake assessed by urinary urea were associated with lower mean urinary creatinine excretion at baseline. Mean annual decline in mGFR was 1.53±0.12 mL/min/1.73 m2 per year and that of urinary creatinine excretion rate, 0.28±0.02 mmol/24 h per year. Patients with fast annual decline in mGFR of 5 mL/min/1.73 m2 had a decrease in urinary creatinine excretion more than twice as big as in those with stable mGFR, independent of changes in urinary urea as well as of other determinants of low muscle mass.ConclusionsDecrease in 24-hour urinary creatinine excretion rate may appear early in CKD patients, and is greater the more mGFR declines independent of lowering protein intake assessed by 24-hour urinary urea. Normalizing urine analytes for creatininuria may overestimate their concentration in patients with reduced kidney function and low muscle mass.

Treatment of chronic kidney disease patients with ketoanalogue-supplemented low-protein diet and ketoanalogue-supplemented very-low-protein diet

A low-protein diet supplemented with ketoanalogues (KAs) has been shown to be effective in improving the benefits of a low-protein diet for patients with chronic kidney disease (CKD). A total of 178 adult patients with CKD Stages 3–5 (predialysis) were assessed for 1 year. A total of 122 patients were in the KA-supplemented low-protein diet (sLPD) group and were prescribed 0.6 g/kg body weight (BW) of dietary proteins supplemented with one KA tablet for every 10 kg BW. The remaining 56 patients were in the KA-supplemented very-low-protein diet (sVLPD) group and received 0.3 g/kg BW of dietary protein supplemented with one KA tablet for every 5 kg BW. Renal, metabolic, and nutritional parameters, and anthropometric assessments were performed for all patients. We assessed the renal function of the patients. There was no difference in the baseline clinical and laboratory characteristics between the sLPD and sVLPD groups. In the sLPD group, the blood urea level decreased from 85.38 ± 4.45 to 76.90 ± 42.90 mg/dL ( p < 0.05) after 12 months. CKD stagewise assessment of the 24-hour urinary creatinine clearance (CrCl) showed an improving trend of renal function. In the sVLPD group, the blood urea level after 6 months decreased from 98.38 ± 42.97 to 79.84 ± 34.15 mg/dL ( p < 0.05), but it increased to 102.74 ± 45.98 mg/dL ( p > 0.05) at the end of 1 year. The CrCl showed a marginal increase at the end of 1 year, but this increase was not statistically significant. There was a decrease in urinary protein excretion in both groups. Anthropometric measurement, including Subjective Global Assessment, showed nutritional improvement in both groups. Pearson correlation coefficient between protein intake and urinary nitrogen appearance showed positive correlation between the two groups. The CKD patients on sLPD and sVLPD showed improvement in renal function, metabolic status, and nutrition. 研究對象為 178 位 3–5 期(透析前)慢性腎病成年患者，其中 122 人接受酮類似物 (KA) 補充之低蛋白飲食 (sLPD)—含每公斤體重 0.6 g 蛋白質及每 10 公斤體重 1 顆 KA 錠；另 56 人接受 KA 補充之極低蛋白飲食 (sVLPD)—含每公斤體重 0.3 g 蛋白質及每 5 公斤體重 1 顆 KA 錠。治療期間的測量項目包括腎功能、代謝、營養學、體格等方面的變化。 在各項基線臨床及化驗特徵上，sLPD 及 sVLPD 兩組之間無明顯差異。經過 12 個月後，sLPD 組的血中尿素從 85.38 ± 4.45 mg/dl 下降至 76.90 ± 42.90 mg/dl ( p < 0.05)，24 小時尿液肌酸酐清除 (CCT) 則顯示，在各級腎病患者中，腎功能呈現改善傾向；至於 sVLPD 組，6 個月的血中尿素從 98.38 ± 42.97 mg/dl 下降至 79.84 ± 34.15 mg/dl ( p < 0.05)，然後於 12 個月增加至 102.74 ± 45.98 mg/dl ( p > 0.05)，12 個月的 CCT 則呈現增加的傾向。在兩組的病人間，尿液蛋白排泄量均明顯下降，體格方面的測量包括 SGA 均呈現營養狀況的改善。兩組間，以 Pearson's 系數分析可見，蛋白質攝取量與尿液氮出現量呈現明顯的相關性。 慢性腎病患者在接受 sLPD 及 sVLPD 期間，腎功能、代謝及營養狀況均呈現出穩定化的情形。

Urine Creatinine–Based Estimates of Fat-Free Mass in Community-Dwelling Older Persons: The Rancho Bernardo Study

To determine whether a previously developed and externally validated equation using common variables (demographics and weight) that are important determinants of muscle mass to estimate 24-hour urine creatinine excretion rate (eCER) is associated with muscle mass and whether spot urine creatinine (UCr) provides similar estimates of muscle mass. Observational cross-sectional cohort study. The Rancho Bernardo Study, San Diego, California. A total of 1,371 Caucasian, middle class, community-dwelling older adults. Morning spot UCr and fat-free mass (FFM) by dual-energy x-ray absorptiometry were measured. eCER was calculated: eCER (mg/day) = 879.89 + 12.51 × weight (kilogram) - 6.19 × age + 34.51 if black - 379.42 if female. Pearson correlation coefficients and linear regression were used to determine strengths of association of eCER and spot UCr with FFM. Mean age was 70 years, and 58% were women. eCER was strongly correlated with FFM (r = 0.95, P < .001), a correlation that was superior to that of spot UCr (r = 0.40, P < .001). An equation incorporating age, weight, sex, and race to estimate eCER is highly correlated with FFM in community-dwelling older persons and provides a more precise estimate than spot UCr. A simple screening tool for sarcopenia in older persons may allow interventions to maintain or improve muscle mass. Future studies should evaluate whether eCER predicts sarcopenia-related frailty and mortality in older persons.

Abstract P188: Urinary Sodium and Potassium Excretion and Cardiovascular Diseases in Patients with Chronic Kidney Disease: the Chronic Renal Insufficiency Cohort study

Introduction: Chronic kidney disease (CKD) patients are at an increased risk of cardiovascular disease (CVD) compared to the general population. Prior studies have produced contradictory results for the associations of sodium and potassium intake with the risk of CVD. In addition, these associations have not been investigated in patients with CKD. Hypothesis: We assessed the prospective associations between urinary sodium and potassium excretion and CVD event rates among patients with CKD. Methods: The Chronic Renal Insufficiency Cohort Study (CRIC) is a prospective cohort study of 3,939 participants with CKD from seven locations in the United States. Dietary sodium and potassium intake are assessed by averaging three 24-hour urinary measures and calibrating to sex-specific mean 24-hour urinary creatinine excretion. Composite CVD event is defined as myocardial infarction (MI), stroke, or congestive heart failure (CHF). CVD events are reported every six months and confirmed by medical record adjudication. Results: Over an average 6.5 years of follow-up, 660 CVD events were observed. The highest quartile (&gt;197.7 mmol/24 hours) of adjusted sodium excretion had a hazard ratio (HR) of 1.52 (95% confidence interval 1.23, 1.88; p for trend across quartiles 70.5 mmol/24 hours) of adjusted potassium excretion had a HR of 1.46 (1.14, 1.87; p for trend across quartiles 0.0009) for composite CVD events compared to the lowest quartile (≤41.2 mmol/24 hours). When modeled continuously, every 100-mmol/24 hours higher adjusted sodium excretion was associated with an increased HR of 1.25 (1.14, 1.36) for composite CVD events, 1.25 (1.13, 1.39) for CHF, 1.32 (1.08, 1.61) for stroke, and 1.09 (0.93, 1.27) for MI. In addition, every 50-mmol/24 hour higher adjusted potassium intake was associated with an increased HR of 1.25 (1.10, 1.41) for composite CVD events, 1.32 (1.15, 1.52) for CHF, 1.11 (0.81, 1.54) for stroke, and 1.00 (0.79, 1.27) for MI. Conclusions: Our study found that high dietary sodium and potassium are both associated with an increased risk of CVD among patients with CKD. These findings suggest that reductions in high dietary sodium and potassium intake might reduce the risk of CVD among patients with CKD.

Abstract P294: Urinary Sodium and Potassium Excretion and Progression of Chronic Kidney Disease

Introduction: Chronic kidney disease is a major risk factor for end-stage renal disease, cardiovascular disease, and premature death. There are scarce data on the effects of dietary sodium and potassium intake on the development and progression of chronic kidney disease. Hypothesis: We investigated the prospective association of urinary sodium and potassium excretion with the risk of chronic kidney disease progression and all-cause mortality among patients with chronic kidney disease. Methods: The Chronic Renal Insufficiency Cohort study is a prospective, longitudinal cohort study among 3,939 patients with chronic kidney disease from 7 clinical centers in the US. Dietary sodium and potassium intake are accessed by averaging three 24-hour urinary measures and calibrating to sex-specific mean 24-hour urinary creatinine excretion. Estimated-glomerular filtration rate was obtained annually. Chronic kidney disease progression was defined as a composite end point of incident end-stage renal disease or halving of estimated-glomerular filtration rate from baseline. Results: A total of 905 events of chronic kidney disease progression and 540 deaths from all-causes were identified during follow-up. Overall, a 100-mmol/24 hours higher adjusted sodium excretion was associated with an increased hazard ratio of 1.28 (95% confidence interval 1.17, 1.41; p&lt;0.0001) for chronic kidney disease progression, 1.35 (1.21, 1.50; p&lt;0.0001) for all-cause mortality, and 1.30 (1.21, 1.41; p&lt;0.0001) for the composite outcome. Similar, a 50-mmol/24 hours higher adjusted potassium excretion was associated with increased hazard ratio of 1.56 (1.36, 1.78; p&lt;0.0001) for chronic kidney disease progression, 1.36 (1.15, 1.62; p=0.0004) for all-cause mortality, and 1.51 (1.35, 1.69; p&lt;0.0001) for the composite outcome after adjustment for important covariables, including baseline kidney function, diuretics, and other antihypertensive medication use. Conclusions: High dietary sodium and potassium intake are associated with increased risk of chronic kidney disease progression and all-cause mortality in patients with chronic kidney disease. These results suggest that a moderate reduction in dietary sodium and potassium intake might slow the progression of chronic kidney disease and reduce all-cause mortality in patients with chronic kidney disease.

Bone Mineral Density and Biochemical Markers of Bone Turnover During the First Year of Injury in Patients with Spinal Cord Injury

BackgroundSpinal cord injury (SCI) is associated with bone mass loss that can be complicated by fractures, which result in further disabilities for patients. After a SCI, the body starts losing large amounts of calcium and other minerals in the urine (demineralisation). This study aimed to assess the changes in bone mineral density (BMD) during the 1st year of acute SCI in patients with neurological deficit. MethodsA total of 95 patients with acute SCI and neurological deficit were evaluated in this prospective study. Haematological investigations such as evaluation of serum calcium, serum phosphate, serum creatinine, and serum alkaline phosphatase (ALP) were carried out. Urinary investigations such as 24-hour urinary creatinine level and excretion of calcium and phosphate in the urine were measured. BMD was measured using dual-energy X-ray absorptiometry scan with Hologic QDR 2000 scanner (Explorer). All of the aforementioned parameters were measured again at 3, 6, and 12 months. ResultsSerum ALP at 1-year follow up was significantly raised (p<0.05). The BMD at 1-year follow up had statistically significant lower values than the initial BMD at the hip (p<0.05), proximal tibia (p < 0.00l), and distal tibial epiphysis (p < 0.001). The BMD in motor-complete SCI patients [American Spinal Injury Association (ASIA) grades A and B] had significant lower values than motor-incomplete SCI patients (ASIA C and D) at the hip (p < 0.05) and proximal tibial epiphysis (p < 0.05). ConclusionThere was a marked decrease in BMD in metaphyseal sites than below the neurological deficit level with maximum decrease at the proximal tibia during the 1st year of SCI. Although the markers of osteoblastic activity did not show much change, the decrease in BMD was influenced by the neurological recovery after SCI.

Abstract T P357: Low Baseline Urine Creatinine Excretion Rate Independently Predicts Severe Disability or Death among Critically Ill Acute Stroke Patients

Background: Urinary creatinine excretion rate (CER) is an established marker of muscle mass and by extension possibly an indicator of physical fitness and cardiovascular structure or function. Low CER has been linked to poor coronary artery disease outcomes, but a link between CER and acute stroke prognosis has not been previously explored. Objective: To evaluate whether low baseline CER is associated with poor outcomes among critically ill acute stroke patients. Methods: We prospectively collected data from patients with acute stroke (ischemic or hemorrhagic) within 24 hours from symptom onset, admitted to a Neurological and Neurosurgery Intensive Care Unit in a hospital in Taiwan between September 2007 and October 2010. Baseline CER (mg/d) was calculated based on 24-hour urine volume and urine creatinine data. Patients were divided into 3 groups according to highest, middle, and lowest CER. Primary endpoint was poor outcome defined as modified Rankin Scale 3-6 at 6 months. Multivariate-adjusted odds ratios (OR) and 95% confidence intervals (CI) for the 6-month mRS were computed using backward stepwise regression analysis. Results: Among 167 critically ill acute stroke patients meeting study entry criteria, 102 (61%) were men, mean age was 68.7 years, 93 (56%) patients had ischemic stroke. Compared to patients in the group with the highest CER levels, patients in the group with the lowest CER levels were older, and had lower body mass index. Patients with lowest CER had poor 6-month outcomes after adjustment for relevant covariates (OR 4.48, 95% CI 1.22 to 16.43, P = 0.024) (Table). Conclusions: Among critically-ill acute stroke patients, low baseline CER was independently associated with poor 6-month outcomes. Validation in other patient populations and a better understanding of the pathophysiologic mechanisms at play is warranted.

Glomerular filtration rates in healthy Asians without kidney disease

The Chronic Kidney Disease Collaboration - Epidemiology (CKD-EPI) glomerular filtration rates (GFR) estimation equation is believed to estimate GFR more accurately in healthy people but this has not been validated in Asians. We studied the distribution of GFR in a multi-ethnic Asian population without CKD, and compared the performance of measures of GFR estimation, including the CKD-EPI equation, Cockroft-Gault equation, and 24-hour urine creatinine clearances. A total of 103 healthy volunteers without a history of kidney disease, hypertension, or diabetes underwent GFR measurement using 3-sample plasma clearance of (99m) Tc-DTPA. Cockroft-Gault estimated GFR and 24-hour urine creatinine clearances were normalized to body surface area. The mean measured GFR was 101 ± 15.8 mL/min per 1.73 m(2) and was lowest in Indians (93 ± 12.3 mL/min per 1.73 m(2); P < 0.001). The CKD-EPI equation appears to be more accurate for healthy participants. Estimated GFR correlated with measured GFR (r = 0.57, P < 0.001), and the mean difference is 3.72 ± 14.43 mL/min per 1.73 m(2) (P < 0.001). However, estimating GFR using self-directed 24-hour urine creatinine clearances is poorer than using the CKD-EPI equation. GFR estimation using self-directed 24-hour urine collection for creatinine clearance is less accurate than using the CKD-EPI equation. A larger study is required to clarify GFR in healthy Asians, and the association of health outcomes of Asian kidney donors with lower GFR thresholds.

Predicted and Measured Creatinine Clearance for the Estimation of Renal Graft Function: New Tools from Body Composition Analysis

Aim of this study was to evaluate, in Renal Transplant Recipients (RTR), a new method to predict Creatinine Clearance (Ccr) from Plasma Creatinine (Pcr) and from the value of Body Cell Mass (BCM). The values of BCM were obtained, from body impedance analysis (BIA) using an impedance plethysmograph, in 87 RTR with different graft function. The ratios of 24-hour Urinary Creatinine Excretion (Ucr) over BCM were calculated in 30 RTR. In the remaining 57 RTR, Ccr was predicted from Pcr and individual values of BCM (BCM Ccr), using the mean ratio Ucr/BCM found in the first group of patients. In the same patients, Ccr was predicted according to Cockcroft and Gault (CG Ccr). The mean of triplicate measurement of 24-hour Ccr (24 h Ccr), obtained by the standard formula Ucr x Vol/min/Pcr, was used as the reference value of renal graft function. BCM Ccr had a better agreement with 24 h Ccr than CG Ccr, particularly in patients with graft failure. Thanks to its simplicity, accuracy and reproducibility, BCM Ccr is more suitable than 24-hour Ccr to estimate graft function. In the meantime, the body composition data gives useful information for the evalutation of nutritional status and of the equilibrium of body fluid compartments.

Secondary Osteoporosis

There are numerous causes of secondary osteoporosis including endocrine disorders, nutritional deficiencies, and other miscellaneous conditions and medications. It is essential to identify and address these factors to appropriately manage patients with osteoporosis. Failure to do so may result in further bone loss despite pharmacologic intervention for osteoporosis. The following diagnostic studies should be considered initially: complete blood count, complete metabolic panel, 25-hydroxyvitamin D level, testosterone level in men, and 24-hour urinary calcium, sodium, and creatinine. Further testing may be performed in selected patients depending on the clinical picture and results of the initial workup.

24-Hour Urinary Calcium in Primary Hyperparathyroidism

To establish whether urinary and serum calcium levels are correlated in patients with primary hyperparathyroidism (PHPT) and to evaluate related factors including serum levels of parathyroid hormone (PTH) and vitamin D, age, gender and renal function. Retrospective review on patients undergoing a parathyroidectomy for PHPT from 2000- 2008. Data collected included: age, sex, preoperative serum calcium (ionized and total), creatinine, PTH, postoperative ionized calcium, vitamin D, and 24-hour urine calcium and creatinine. Data were evaluated by standard descriptive statistics. Of the 214 patients evaluated, preoperative 24-hour urinary calcium was available for 150 patients (70%). 24-hour urine calcium levels did not correlate significantly with preoperative total serum or ionized calcium, PTH, vitamin D, or postoperative serum ionized calcium. There were significant correlations (P<0.0001) of 24-hour urinary calcium with age, serum creatinine, and urine creatinine. Secondary analysis grouped subjects by urinary calcium level greater or less than 400 mg/24 hours. Age and urinary creatinine were significantly different between the two groups. CONCLUSIONS In patients with PHPT who underwent parathyroidectomy, there was little correlation between preoperative 24-hour urine calcium and preoperative serum calcium, PTH, or vitamin D levels. 24-hour urine calcium levels were correlated with renal function and age, but these correlations are likely to occur in the general population and are not specific to this disease group.

Kidney Transplant Donor Glomerular Filtration Rate by Iohexol Clearance During Computerized Tomographic Angiography of the Kidneys

BackgroundPre-transplantation living-donor kidney function determines remaining donor kidney function and significantly affects post-transplantation allograft function in the recipient. Few transplantation centers perform donor kidney function measurement owing to patient burden. A simplified method of glomerular filtration rate (GFR) measurement after angiographic procedures may facilitate more precise measurement of donor kidney function. MethodsWe evaluated the agreement between a simplified method of GFR measurement after renal computerized tomographic (CT) angiography (index GFR, 100 mL iohexol [350 mg/mL iodine]) and the reference GFR measurement with the use of iodinated radiocontrast media (5 mL bolus of iohexol [300 mg/mL iodine]) among 19 potential living kidney transplant donors. The 24-hour creatinine clearance and GFR estimation equations were additionally examined. Kidney lengths and total and segmented cortical kidney volumes were also measured. ResultsThe index CT angiography GFR performed best with respect to the reference GFR with minimal bias (mean difference, −4 mL/min/1.73 m2), good precision (SD of the difference, 9.8 mL/min/1.73 m2), coefficient of determination (R2) of 0.74, narrow mean coefficient of variation (5% [range 1%–15%]), and high accuracy, with 100% of the values for the index test within 30% of the reference test. The 24-hour urine creatinine clearance values performed poorly. Kidney volumes and length did not significantly correlate with measured GFR. ConclusionsThe CT angiographic GFR measurement could be a useful and more convenient method of donor kidney function evaluation and maintains minimal bias, high precision, and accuracy compared with the reference GFR measurement.

A Good Reason to Measure 24-Hour Urine Creatinine Excretion, but Not to Assess Kidney Function

Collection of a 24-hour urine sample and measurement of creatinine clearance made up the standard of care for assessing kidney function for years until regression formulas for estimation of GFR were developed. As a result, 24-hour urine sample collection is used much less frequently in current

Comparison of Creatinine Clearance Estimates With Routine Measured Clearance in Adult Jordanians With a Kidney Transplant

There are conflicting data on using the Cockroft-Gault formula and the Modification of Diet in Renal Disease formula to assess graft function in kidney transplants. This study uses a cohort of Jordanian kidney transplant patients to assess performance of the Cockroft-Gault formula and the Modification of Diet in Renal Disease equations by using the criterion standard of measured creatinine clearance. Creatinine clearance measured by 24-hour urine creatinine in patients with a kidney transplant was compared with the estimated clearance using the Cockroft-Gault formula and the Modification of Diet in Renal Disease equations. Correlation, limits of agreement, and concordance analyses were used. There was a positive correlation between both the Cockcroft-Gault (r=0.878; P < .001) and the Modification of Diet in Renal Disease (r=0.732; P < .001) equations with creatinine clearance. The former was statistically superior (P = .0416). Using Bland-Altman plots, the limits of agreement were wide for both methods. After log transformation, the limits of agreement were -0.06 to +0.27 for the Cockcroft-Gault formula, and -0.21 to + 0.26 for the Modification of Diet in Renal Disease. Concordance analyses showed a correlation coefficient of 0.7384 (95% CI: 0.6134 to 0.8273) when the Cockcroft-Gault formula was used, and 0.7257 (95% CI: 0.5622 to 0.8345) for the Modification of Diet in Renal Disease. Pearson P coefficient (precision) and bias correction factor Cb (accuracy) for the Cockcroft-Gault formula and for the Modification of Diet in Renal Disease were 0.8762, 0.8427, 0.7324, and 0.9908. In Jordanian patients with a renal transplant, although the Cockcroft-Gault formula performed slightly better than the Modification of Diet in Renal Disease equation in estimating creatinine clearance, neither of these equations can accurately predict renal graft function.

Estimating the glomerular filtration rate from serum creatinine is better than from cystatin C for evaluating risk factors associated with chronic kidney disease

Chronic kidney disease risk factors may associate with the estimated glomerular filtration rate (eGFR) differently than with the measured GFR. To examine this, we evaluated 1150 patients (mean age 65) in two community cohorts for risk factors, measured GFR by iothalamate clearance, and eGFR based on creatinine (Cr), cystatin C (CysC), or both. The interaction between each risk factor and eGFR (relative to measured GFR) identified risk factor associations with eGFR along non-GFR pathways. In a subset of 40 patients with two visits, the mean coefficient of variation was 8.2% for measured GFR, 6.4% for eGFRCr, 8.2% for eGFRCr-CysC, and 10.7% for eGFRCysC. The measured GFR was better correlated with eGFRCr-CysC (r, 0.74) than eGFRCr (r, 0.70) or eGFRCysC (r, 0.68). Lower measured GFR associated with lower 24-hour urine creatinine, albuminuria, hypertension, diabetes, higher triglycerides, and higher uric acid. Lower eGFRCr had these same associations except for an association with higher 24-hour urine creatinine along a non-GFR pathway. Lower eGFRCysC and eGFRCr-CysC also had these same associations but also associated with obesity, albuminuria, hypertension, diabetes, higher triglycerides, higher C-reactive protein, and higher uric acid along non-GFR pathways. Thus, cystatin C improves estimation of GFR over creatinine alone; however, the association between most of the risk factors and GFR was more accurate by eGFR based on creatinine alone. This is explained by the association of these risk factors with the non-GFR determinants of cystatin C.

Associations between radiographic characteristics and change in renal function following partial nephrectomy using 24-hour creatinine clearance

Background: Radiographic characteristics may be associated withthe degree of renal function preservation following partial nephrectomy.The purpose of this study was to determine the impact ofpreoperative radiographic variables on change in renal functionusing 24-hour urine creatinine clearance (uCrCl).Methods: Patients with partial nephrectomy performed fromNovember 2003 to 2008 were enrolled in the study. Serum creatinineand 24-hour urine was collected preoperatively and at3, 6 and 12 months postoperatively. Computed tomography ormagnetic resonance imaging was used to determine tumour size,tumour location and renal volume.Results: Of the 36 patients, median age was 62 (range 30-78) and21 (58%) were male. The mean tumour diameter was 2.8±1.4 cm.Twenty-two (61%) tumours were located at the renal pole and11 (31%) were endophytic. Overall, mean preoperative uCrClwas 88.8±34.2 mL/min and mean postoperative uCrCl was82.8±33.6 mL/min (6.8%; p &lt; 0.01). On multivariable analysis,no single characteristic was associated with a clinically prohibitivedecrease in renal function (-9.4% if endophitic, p = 0.06; -0.57%per cm diameter, p = 0.73; and -6.9% if located at the renal pole,p = 0.15). The total renal volume was also not significantly associatedwith renal function change (-1.1% per 100 cc, p = 0.86).Interpretation: Preoperative radiographic characteristics seem tobe associated with small changes in renal function following partialnephrectomy. These data support renal functional benefits of partialnephrectomy regardless of tumour size and location.