Urinary albumin excretion in healthy adults: a cross sectional study of 24-hour versus timed overnight samples and impact of GFR and other personal characteristics

Urinary podocyte markers in diabetic kidney disease

Podocytes are involved in maintaining kidney function and are a major focus of research on diabetic kidney disease (DKD). Urinary biomarkers derived from podocyte fragments and molecules have been proposed for the diagnosis and monitoring of DKD. Various methods have been used to detect intact podocytes and podocyte-derived microvesicles in urine, including centrifugation, visualization, and molecular quantification. Quantification of podocyte-specific protein targets and messenger RNA levels can be performed by Western blotting or enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. At present, many of these techniques are expensive and labor-intensive, all limiting their widespread use in routine clinical tests. While the potential of urinary podocyte markers for monitoring and risk stratification of DKD has been explored, systematic studies and external validation are lacking in the current literature. Standardization and automation of laboratory methods should be a priority for future research, and the added value of these methods to routine clinical tests should be defined.

Assessment of Changes in Physiological Markers in Different Body Fluids at Rest and after Exercise

Physiological and biological markers in different body fluids are used to measure the body’s physiological or pathological status. In the field of sports and exercise medicine, the use of these markers has recently become more popular for monitoring an athlete’s training response and assessing the immediate or long-term effects of exercise. Although the effect of exercise on different physiological markers using various body fluids is well substantiated, no article has undertaken a review across multiple body fluids such as blood, saliva, urine and sweat. This narrative review aims to assess various physiological markers in blood, urine and saliva, at rest and after exercise and examines physiological marker levels obtained across similar studies, with a focus on the population and study methodology used. Literature searches were conducted using PRISMA guidelines for keywords such as exercise, physical activity, serum, sweat, urine, and biomarkers, resulting in an analysis of 15 studies for this review paper. When comparing the effects of exercise on physiological markers across different body fluids (blood, urine, and saliva), the changes detected were generally in the same direction. However, the extent of the change varied, potentially as a result of the type and duration of exercise, the sample population and subject numbers, fitness levels, and/or dietary intake. In addition, none of the studies used solely female participants; instead, including males only or both male and female subjects together. The results of some physiological markers are sex-dependent. Therefore, to better understand how the levels of these biomarkers change in relation to exercise and performance, the sex of the participants should also be taken into consideration.

Urinary Concentration Correction Methods for Arsenic, Cadmium, and Mercury: a Systematic Review of Practice-Based Evidence

BACKGROUND

Urinary biomonitoring is widely used to assess environmental chemical exposure; however, a critical gap exists in whether and how to correct for the physiological variation in water content of spot urine samples.

OBJECTIVE

The aim of this systematic review is to summarize the available evidence comparing the performance of urinary concentration correction methods used to determine urinary levels of arsenic, cadmium, and mercury.

METHODS

We searched PubMed/MEDLINE, Embase, LILIAC, Web of Science, and TOXNET up to Sept. 5, 2017 for articles evaluating urinary concentration correction methods (e.g., urine creatinine [U-Cre], specific gravity [U-SG], osmolality [U-Osm]) compared to 24-h or timed urine specimens for levels of arsenic, cadmium, and mercury. Data on study design, methods of urine collection, and the performance of selected correction methods were extracted.

RESULTS

A total of 10 papers met the inclusion criteria. Two papers evaluated the performance of urinary concentration correction methods for arsenic, four for cadmium, three for mercury, and one for multiple metals. The median sample size for arsenic was 105, for cadmium 107, and for mercury 35. The studies were highly heterogeneous in population selection, urine collection, urine quality control, statistical comparison among selected correction methods, and presentation of the results. The median (range) of correlation coefficients comparing each corrected values with corresponding levels of timed urine specimens are 0.74 (0.17-0.92) for un-correction (n = 13), 0.82 (0.52-0.98) for U-Cre (n = 13), and 0.75 (0.28-0.98) (n = 12) for U-SG.

CONCLUSION

Findings from limited evidence support that urine creatinine and urine-specific gravity corrections remain practical approaches to correct metal concentrations for urine dilution as compared to 24-h or 12-h urine samples. Further studies with larger sample sizes are needed to clarify this fundamental issue of environmental biomonitoring using spot urine samples in both general and priority populations.

Normative noninvasive bladder function measurements in healthy women: A systematic review and meta-analysis

AIM

To conduct an evidence synthesis of normative reference values for bladder function parameters in women.

METHODS

We conducted a systematic review and meta-analysis of studies reporting bladder function parameters obtained from noninvasive tests in healthy women. Seven databases were searched for relevant studies from inception through December 2018, with manual searching of reference lists. We included English language articles that provided quantitative data on urination frequency, voided and postvoid residual volumes, and uroflowmetry results in women without lower urinary tract symptoms. Study selection, data extraction, and quality assessment were undertaken by at least two independent reviewers. Random-effects meta-analytic models were used to derive study-level pooled mean estimates and 95% confidence intervals.

RESULTS

A total of 24 studies (N = 3090 women, age range, 18-91 years) met eligibility criteria. Pooled mean estimates of bladder function parameters were: 6.6 daytime voids (95% confidence interval (95% CI), 6.2, 7.0), 0.4 nighttime voids (95% CI, 0.0, 0.8), 1577 mL for 24-hour voided volume (95% CI 1428,1725); 12 mL for postvoid residual volume (95% CI, 4, 20); and 28 mL/sec for maximum flow rate (95% CI, 27,30). Between-study heterogeneity was high for all outcomes (I²  = 61.1-99.6%), but insufficient data were available to explore reasons for this high heterogeneity (eg, differences by age).

CONCLUSION

Although summary mean estimates of bladder function parameters were calculated, the wide heterogeneity across studies precludes generalization of these estimates to all healthy women. Further research is needed to determine normative reference values within specific groups, such as those defined by age.

Prediction of Preeclampsia in Early Pregnancy by Estimating the Spot Urinary Albumin/Creatinine Ratio

OBJECTIVE

To assess whether a spot urinary albumin:creatinine ratio (ACR) measured before 20 weeks of gestation can predict subsequent development of preeclampsia.

METHODS

The ACR was determined from midstream urine sample taken between 17 and 20 weeks of gestation. Urine albumin was measured by immunoturbidimetric method using commercially available kit (Beckman Coulter) through Beckman AU 480 fully automated biochemistry analyzer. Urine creatinine was measured by modified kinetic Jaffe reaction without deproteinization.[Formula: see text]Participants were then followed until delivery. Primary outcome measure was preeclampsia, secondary outcome measures were gestational hypertension, gestational diabetes mellitus, IUGR, and normal range estimate of urinary albumin-to-creatinine ratio was established.

RESULT

The median spot urinary albumin-to-creatinine ratio measured between 17 and 20 weeks of gestation was 5.2 mg/g of creatinine (2.5-9.6). Women who subsequently developed preeclampsia had higher spot urinary albumin-to-creatinine ratio (median 30.795 [9.7-92.8]) in comparison with women who developed gestational hypertension (median 5.2 [0.7-7.2]) and unaffected women (median 5.2 [2.5-9.6]). The urinary albumin-to-creatinine ratio of the mother who developed IUGR was significantly higher. By ROC analysis, the optimum ACR to predict preeclampsia was 9.85 mg/g of creatinine. The relative risk of developing preeclampsia in women with urinary albumin-to-creatinine ratio more than 9.85 mg/g of creatinine was higher than in the women who had urinary albumin-to-creatinine ratio less than 9.85 mg/g of creatinine.

CONCLUSION

A spot urinary albumin-to-creatinine ratio of more than 9.8 mg/g of creatinine can predict the development of preeclampsia in later pregnancy with the sensitivity and specificity of 67 and 76%, respectively. However, additional studies and cost-benefit analysis are required to confirm these finding before recommending this test for screening purposes.