Nephrogenic Diabetes Insipidus Presenting with Hypokalemic Paralysis in an Adolescent with Primary Sjögren's Syndrome: A Case Report.

INTRODUCTION

Diabetes insipidus is a rare disorder characterized by polyuria, polydipsia, and dilute urine. Nephrogenic diabetes insipidus (NDI) secondary to distal renal tubular acidosis (dRTA) in primary Sjögren's syndrome (pSS) is exceedingly rare in children.

CASE PRESENTATION: A 16-year-old girl presented with hypokalemic paralysis (potassium 1.89 mmol/L), polyuria (>5 L/day), and growth retardation (height 141 cm, <3rd percentile). Laboratory studies revealed dRTA with secondary NDI. Autoimmune workup confirmed pSS. A systematic literature review identified only 5 similar pediatric cases. Initial management with hydrochlorothiazide exacerbated hypokalemia and precipitated hypochloremic metabolic alkalosis. Switching to amiloride combined with glucocorticoids and potassium supplementation normalized electrolytes, reduced urine output to 1.5 L/day, and resulted in catch-up growth at the 6-month follow-up.

CONCLUSION

This case highlights the pathophysiologic cascade of pSS-related dRTA causing secondary NDI and underscores the importance of early recognition and tailored diuretic selection in adolescents.