Urinary gamma-glutamyl transferase-to-creatinine ratio as an indicator of tubular function in Bence Jones Proteinuria

Renal tubular epithelial cells add value in the diagnosis of upper urinary tract pathology

Background Diagnosis of upper urinary tract infections (UTI) is challenging. We evaluated the analytical and diagnostic performance characteristics of renal tubular epithelial cells (RTECs) and transitional epithelial cells (TECs) on the Sysmex UF-5000 urine sediment analyzer. Methods Urinary samples from 506 patients presenting with symptoms of a UTI were collected. Only samples for which a urinary culture was available were included. Analytical (imprecision, accuracy, stability and correlation with manual microscopy) and diagnostic performance (sensitivity and specificity) were evaluated. Results The Sysmex UF-5000 demonstrated a good analytical performance. Depending on the storage time, storage conditions (2-8 °C or 20-25 °C) and urinary pH, RTECs and TECs were stable in urine for at least 4 h. Using Passing-Bablok and Bland-Altman analysis, an acceptable agreement was observed between the manual and automated methods. Compared to TECs, RTECs demonstrated an acceptable diagnostic performance for the diagnosis of upper UTI. Conclusions While TECs do not seem to serve as a helpful marker, increased urinary levels of RTECs add value in the diagnosis of upper UTI and may be helpful in the discrimination between upper and lower UTIs.

Distribution of urinary gamma-glutamyltransferase activity in 40- to 74-year-old Japanese women

Urinary gamma-glutamyltransferase (u-γGT) concentration (U/L) and excretion (urinary creatinine-corrected u-γGT; u-γGT/u-Cre, U/g creatinine) are useful markers for kidney disease. However, there is limited information available on u-γGT and u-γGT/u-Cre distribution in the elderly Japanese population. In this study, we investigated the distribution of u-γGT and u-γGT/u-Cre in 113 Japanese women aged 40–74 years. The u-γGT was assessed from spot urine samples (collected from 09:00 to 14:00) spectrophotometrically according to the Japan Society of Clinical Chemistry reference measurement procedure using l-γ-glutamyl-3-carboxy-4-nitroanilide as the substrate. The u-Cre was measured enzymatically using creatininase, creatinase, sarcosine oxidase, and peroxidase. None of the participants was diagnosed with any kidney disease. Median u-γGT and u-γGT/u-Cre values (central 95% interval values) were 29.7 (5.3–144.0) U/L and 57.9 (32.9–122.7) U/g creatinine, respectively. The distribution of u-γGT tended to decline with age. There was a statistically significant difference in the u-γGT value between the 40-59- and 60-74-year-old groups. In contrast, there was no significant difference in the u-γGT/u-Cre between each age group. The u-Cre level also declined with age. It is suggested that the decline of u-γGT with aging would be masked by the u-Cre correction.

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Median (central 95% interval values) u-γGT value was 29.7 (5.3–144.0) U/L.

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Median (central 95% interval values) u-γGT/u-Cre ratio was 57.9 (32.9–122.7) U/g creatinine.

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Distribution of u-γGT tends to decline with age.

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u-Cre levels also declined with age.

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Decline of u-γGT with aging would be masked by the u-Cre correction.

mTORC1 inhibitors rapamycin and metformin affect cardiovascular markers differentially in ZDF rats

Mammalian target for rapamycin complex 1 (mTORC1) is a common target for the action of immunosuppressant macrolide rapamycin and glucose-lowering metformin. Inhibition of mTORC1 can exert both beneficial and detrimental effects in different pathologies. Here, we investigated the differential effects of rapamycin (1.2 mg/kg per day delivered subcutaneously for 6 weeks) and metformin (300 mg/kg per day delivered orally for 11 weeks) treatments on male Zucker diabetic fatty (ZDF) rats that mimic the cardiorenal pathology of type 2 diabetic patients and progress to insulin insufficiency. Rapamycin and metformin improved proteinuria, and rapamycin also reduced urinary gamma glutamyl transferase (GGT) indicating improvement of tubular health. Metformin reduced food and water intake, and urinary sodium and potassium, whereas rapamycin increased urinary sodium. Metformin reduced plasma alkaline phosphatase, but induced transaminitis as evidenced by significant increases in plasma AST and ALT. Metformin also induced hyperinsulinemia, but did not suppress fasting plasma glucose after ZDF rats reached 17 weeks of age, and worsened lipid profile. Rapamycin also induced mild transaminitis. Additionally, both rapamycin and metformin increased plasma uric acid and creatinine, biomarkers for cardiovascular and renal disease. These observations define how rapamycin and metformin differentially modulate metabolic profiles that regulate cardiorenal pathology in conditions of severe type 2 diabetes.