Study of Urinary Electrolytes and Fractional Excretion of Uric Acid in Evaluating Hyponatremia.

INTRODUCTION

Serum sodium levels <135 mmol/L are known as hyponatremia. The syndrome of inappropriate antidiuresis (SIAD), which is described by a drop in the effective arterial blood volume (EABV), is the most common cause of hyponatremia. This study was carried out to categorize hyponatremia based on volume status and on parameters like fractional excretion of uric acid (FE-UA), fractional excretion of sodium (FE-Na), urine uric acid (U-UA), and serum uric acid (SR-UA) values.

MATERIALS AND

METHODS

Sixty-one patients admitted to the Department of Medicine at Rajendra Institute of Medical Sciences (RIMS), Ranchi, with hyponatremia were included in the study by applying random sampling. Routine urine and blood samples were collected for biochemical tests. Institutional ethical clearance was obtained for this study. Data were analyzed using Statistical Package for the Social Sciences (SPSS) (version 21). Frequency, central tendency, receiver operating characteristic (ROC), and nonparametric Mann-Whitney U test analysis tools were utilized for analysis.

RESULTS

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) was found in nearly 50.82% of hyponatremic patients. Approximately, 70% of non-SIADH patients were hypovolemic. When compared to the non-SIADH group, patients in the SIADH group had significantly higher systolic blood pressure (SBP) and diastolic blood pressure (DBP), lower pulse rates, and lower urine creatinine levels and urine creatinine to serum creatinine ratio. The non-SIADH group had significantly higher SR-UA levels (p < 0.0001), but the SIADH group had significantly higher U-UA levels and significantly lower SR-UA levels. Among the studied parameters, FE-UA was the most accurate in diagnosing SIADH. FE-UA (>12%) is a better diagnostic marker for distinguishing SIADH patients from non-SIADH patients.

CONCLUSION

FE-uric acid was found to be the most superior in diagnosing SIADH, followed by FE-Na.