RESUMO
OBJECTIVE: To present a case of untreated long-term idiopathic neurohypophysial diabetes insipidus (DI) with structural and functional renal abnormalities that regressed after treatment. METHODS: We describe the clinical course, biochemical data, and imaging findings in a man with idiopathic neurohypophysial DI in whom structural and functional abnormalities involving the urinary tract diminished after treatment. The patient underwent intravenous pyelography, retrograde pyelography, computed tomographic (CT) scanning of the kidneys and abdomen, iodohippurate renal scanning, and voiding cystourethrography. Ultrasonography of the kidneys at presentation and at 8-year followup and serial determinations of serum creatinine for a period of 9 years were also done. RESULTS: A 43-year-old man had polyuria for 30 years attributable to untreated idiopathic neurohypophysial DI. He presented with bilateral flank pain and a high serum creatinine level (156 mmol/L). Ultrasonography, intravenous pyelography, retrograde pyelography, and CT scan of the kidneys demonstrated severe bilateral hydronephrosis, notably dilated and tortuous ureters, a distended bladder, and atrophy of the left renal cortex. Retrograde pyelography and voiding cystourethrography confirmed the absence of mechanical obstruction or urinary reflux. A renal scan study showed bilaterally impaired function. Treatment with intranasally administered desmopressin and clean intermittent straight bladder catheterization resulted in resolution of flank pain, improvement of renal function, normalization of serum creatinine levels, and decreased hydronephrosis during 9 years of follow-up. CONCLUSION: This case provides information about renal abnormalities in the natural history of a long-term polyuric state, idiopathic neurohypophysial DI, before and after treatment. Reversibility of renal structural and functional abnormalities after treatment is documented. Recognition of renal abnormalities associated with untreated neurohypophysial DI is important for prevention and treatment of such complications.