Endocrinology Quiz #15: Primary Polydipsia and Diabetes Insipidus

1. A 24-year-old man presents to his primary care physician with complaints of excessive urination and constant thirst over the past few months. A water deprivation test shows a gradual increase in urine osmolality that normalizes with the administration of desmopressin. Which of the following is the most likely diagnosis? 

Question 1 of 5

2. A 35-year-old woman is referred to an endocrinologist for evaluation of her persistent thirst and polyuria. She reports drinking up to 6 liters of water a day. Laboratory tests reveal low serum sodium and normal kidney function. A water deprivation test fails to significantly alter urine osmolality, but there are no improvements with desmopressin administration either. Which of the following is the most likely diagnosis? 

Question 2 of 5

3. A 7-year-old boy is brought to the pediatrician by his parents who are concerned about his sudden increase in thirst and urination. The child has a history of a head injury from a fall 2 months ago. After conducting appropriate tests, the pediatrician concludes that the child cannot concentrate his urine in response to water deprivation, but shows a significant response to desmopressin. What is the underlying cause of this child's symptoms?

Question 3 of 5

4. A patient diagnosed with lithium-induced nephropathy presents with polyuria and polydipsia. Laboratory tests reveal normal serum ADH levels. Despite administration of desmopressin, there is no significant change in urine osmolality. Which of the following conditions is most consistent with these findings? 

Question 4 of 5

5. A 40-year-old man with a history of bipolar disorder treated with lithium for several years presents with complaints of increased thirst and urination. His serum sodium is elevated, and urine osmolality remains low despite water deprivation. Administration of desmopressin results in no significant change in urine osmolality. Given the patient's medication history, which of the following is the most appropriate next step in management? 

Question 5 of 5


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