Mood Disorders · NEET PG Preparation Psychiatry
A 45-year-old man with a 10-year history of Bipolar I disorder, successfully maintained on lithium carbonate for the past 5 years, presents for routi…
Practice question from Mood Disorders (NEET PG Preparation Psychiatry), with the correct answer and a step-by-step solution.
medium · MCQ · Q-B07507
A 45-year-old man with a 10-year history of Bipolar I disorder, successfully maintained on lithium carbonate for the past 5 years, presents for routine follow-up. He complains of passing a large volume of dilute urine (approx 4.5 liters/day) and excessive thirst. His serum sodium is 142 mEq/L, serum osmolality is 295 mOsm/kg, and urine osmolality is 180 mOsm/kg. Which of the following is the underlying pathophysiological mechanism of this complication?
- A.Inhibition of the action of antidiuretic hormone (ADH) in the collecting ductsCorrect answer
- B.Destruction of the posterior pituitary gland by lithium deposition
- C.Autoimmune destruction of the distal convoluted tubules
- D.Excessive secretion of atrial natriuretic peptide causing a salt-wasting nephropathy
Solution
Lithium-induced nephrogenic diabetes insipidus occurs because lithium enters the principal cells of the collecting duct via epithelial sodium channels (ENaC) and downregulates aquaporin-2 water channels, rendering the collecting duct unresponsive to antidiuretic hormone (ADH).
More from Mood Disorders
- A 32-year-old male is brought to the psychiatry emergency by his family. He presents with a 2-week history of persistently elevated mood, d…
- A 28-year-old female presents with recurrent depressive episodes alternating with periods of mild elevation of mood and increased energy la…
- A 55-year-old female is diagnosed with severe major depressive disorder with psychotic features. She has failed trials of multiple selectiv…
- A 36-year-old pregnant woman at 12 weeks gestation presents with a severe depressive relapse. She has a history of severe recurrent major d…
Practise more Psychiatry
Sign up free for adaptive practice on this chapter, with instant feedback and hints on every question.
Start practising freeFree to start · No credit card needed