A 46-year-old man with bipolar disorder presents with polyuria and polydipsia. He has taken lithium for 8 years. Vital signs show BP 138/82 mmHg, HR 88/min, RR 16/min, temp 37°C, SpO2 98%. Serum sodium is 149 mEq/L; serum creatinine 1.2 mg/dL. Urine osmolality remains 285 mOsm/kg despite water deprivation and minimal response to desmopressin. Urinalysis shows no proteinuria. Which mechanism best explains his presentation?
- A)Deficient release of antidiuretic hormone from the posterior pituitary
- B)Impaired response of collecting duct principal cells to antidiuretic hormoneGABARITO
- C)Enhanced aquaporin insertion into the collecting duct membrane
- D)Constitutive activation of vasopressin V2 receptors
- E)Excess secretion of aldosterone from the adrenal cortex
Explicação
Lithium commonly causes nephrogenic diabetes insipidus by impairing ADH action in collecting duct principal cells. Because the kidney is resistant, urine remains dilute despite water deprivation and after desmopressin administration. Ver explicação completa e trilha adaptativa →