Chronic lithium therapy can cause which renal complication leading to polyuria?

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Multiple Choice

Chronic lithium therapy can cause which renal complication leading to polyuria?

Chronic lithium therapy most commonly causes nephrogenic diabetes insipidus, a condition where the kidney cannot concentrate urine in response to vasopressin. Lithium enters collecting duct principal cells and disrupts the signaling that normally increases water reabsorption. It reduces the activity or presence of aquaporin-2 water channels on the cell surface, so even when antidiuretic hormone is present, water reabsorption is blunted. The result is production of large volumes of dilute urine (polyuria) with accompanying thirst. Other renal problems listed don’t fit this pattern: SIADH would cause water retention and hyponatremia with concentrated urine; acute tubular necrosis presents with oliguria and declining kidney function; Fanconi syndrome involves proximal tubule dysfunction with findings like glycosuria and bicarbonate wasting, not a primary cause of polyuria.

Chronic lithium therapy most commonly causes nephrogenic diabetes insipidus, a condition where the kidney cannot concentrate urine in response to vasopressin. Lithium enters collecting duct principal cells and disrupts the signaling that normally increases water reabsorption. It reduces the activity or presence of aquaporin-2 water channels on the cell surface, so even when antidiuretic hormone is present, water reabsorption is blunted. The result is production of large volumes of dilute urine (polyuria) with accompanying thirst.

Other renal problems listed don’t fit this pattern: SIADH would cause water retention and hyponatremia with concentrated urine; acute tubular necrosis presents with oliguria and declining kidney function; Fanconi syndrome involves proximal tubule dysfunction with findings like glycosuria and bicarbonate wasting, not a primary cause of polyuria.

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