Evaluation of Early Renal Involvement in Essential Hypertension by Measuring Urinary Biomarkers

Hypertensive kidney damage results in glomerular as well as tubular dysfunction. Albuminuria is a well-known marker of glomerular damage. On the other hand, urinary uromodulin is increasingly considered as a potential biomarker of early tubular dysfunction. The aim of the study was to assess glomerular and tubular function of the kidney by measuring urinary albumin and uromodulin excretion in hypertensive subjects. This cross-sectional study was conducted from July 2018 to June 2019 in Hypertension Clinic of Dhaka Medical College Hospital, Dhaka and Kidney Care and Research Centre, Sonargaon, Narayanganj, Bangladesh. In this study 122 hypertensive subjects with age >30 years, duration of hypertension <5 years, without accelerated or malignant BP, absence of dipstick proteinuria and eGFR >60ml/min were included. There were also 33 normotensive individuals included as healthy controls. Albumin-creatinine ratio (uACR mg/g), urine uromodulin-creatinine ratio (uUMODμg/g), urinary sodium-creatinine ratio (mEq/g) and potassium-creatinine ratio (mEq/g) were measured from single morning spot urine sample. Urinary uromodulin levels were measured by ELISA method. The hypertensive and normotensive subjects were age matched 49.0±12.0 vs. 48.0±11.0, years (p=NS). The mean uACR was 29.0±65.0 versus 5.6±2.7mg/g, (p<0.001) respectively. The median uUMOD in hypertensive subjects was 3.38 (1.73-9.06) and in normotensives 3.85(2.28-5.69) μg/g (p=non significant). Multivariate analysis showed significant inverse association between diastolic blood pressure and urinary uromodulin excretion. A uUMOD cut-off of 2.9 (25th percentile) showed eGFR, urinary sodium and potassium excretions were significantly lower at low uromodulin group. The glomerular involvement was found in 21.0% of hypertensive subjects as evidenced by albuminuria. No difference was observed in urinary uromodulin level between hypertensive and normotensive subjects. Low urinary uromodulin level was associated with lower eGFR, Na+ and K+ excretion which indicate simultaneous tubular and glomerular involvement.