Short-term Changes in Urine Beta 2 Microglobulin Following Recovery of Acute Kidney Injury Resulting From Snake Envenomation.

Introduction: Urine β2 microglobulin (β2m) is a validated marker to diagnose sepsis and toxin-related acute kidney injury (AKI). In the current study, we used urine β2m as a potential marker to identify persistent tubular dysfunction following a clinical recovery from snake venom-related AKI.

Methods: A total of 42 patients who developed AKI following hemotoxic envenomation were followed up for a period of 6 months. Urine albumin excretion, estimated glomerular filtration rate (eGFR), and urine β2m levels were measured at 2 weeks, 3 months, and 6 months following discharge.

Results: At the end of 6 months of follow-up, 6 patients (14.3 %) progressed to chronic kidney disease (CKD) (eGFR < 60 ml and/or urine albumin excretion > 30 mg/d). The urine β2m levels were 1590 μg/l (interquartile range [IQR] 425-5260), 610 μg/l (IQR 210-1850), 850 μg/l (IQR 270-2780) at 2 weeks, 3 months, and 6 months, respectively ( P  = 0.020). The levels of urine β2m in the study population at the end of 6 months remained significantly higher compared with the levels in healthy control population (850 μg/l [IQR 270-2780] vs. 210 μg/l [IQR 150-480]; P  = 0.001). The proportion of patients with urine β2m levels exceeding the 95th percentile of control population (>644 µg/l) during the 3 follow-up visits were 70.7% ( n  = 29), 48.8 % ( n  = 20), and 51.2% ( n  = 21). Similar trends were noticed in a sensitivity analysis, after excluding patients with CKD.

Conclusions: Urine β2m levels remain persistently elevated in approximately half of the individuals who recover from AKI due to snake envenomation.