Hypokalemia-induced Polyuria with Nocturia after Intravenous Methylprednisolone Pulse Therapy in a Henoch-Schonlein Purpura Nephritis Patient

ABSTRACT

Patients with moderate to severe degrees of Henoch-Schonlein purpura (HSP) nephritis receive high-dose intravenous methylprednisolone pulse therapy (IMPT). Although the regimen is generally safe and effective, various complications occasionally develop. administration of excessive corticosteroid can induce urinary potassium wasting leading to hypokalemia. Polyuria, one of the complications of hypokalemia, is related to both increased thirst and mild nephrogenic diabetes insipidus. And hypokalemia itself also impairs the maximal renal urinary concentration ability. Although polyuria or nocturia after IMPT is not common, it is correctable immediately by oral potassium supplementation. Therefore, during IMPT, careful history taking of nocturia as well as monitoring urine volume, serum and urine potassium level at regular follow-up are necessary because even mild hypokalemia can provoke urine concentrating ability defect. We experienced a case of 11 year-old boy with HSP nephritis who suffered from hypokalemia-induced polyuria with nocturia right after IMPT.