HY USMLEQ#15 Endo Step 1
HY USMLE Q#15 Endocrinology
(Step 1 and Step 2 CK level inspired by Mehlman video 1448)
A 50-year-old man comes to the doctor due to 5 months of gradual worsening fatigue. Also, he has lost 7 pounds during this time. His temperature is 98.9°F, respiratory rate 13/ min, and blood pressure is 100/60 mmHg. Physical examination reveals darkening of the skin in the forearms. Additionally, serum ACTH is elevated. What is most likely to be seen in this patient?
A. Serum sodium of 149 meal/l
B. Hilar coin Lesion
C. Failure of suppression with high-dose Dexamethasone
D. Decrease Corticotropin-releasing hormone
E. Esoniophils of 16%
✅ Correct answer = Choice E. Eosinophils of 16%
Education Objective:
Cortisol normally causes apoptosis of T-lymphocytes and eosinophils, but it increases neutrophils by causing demargination of neutrophils from the blood vessel walls into the circulation. It also reduces neutrophil migration into tissues by inhibiting adhesion molecules. Hence, if we have low cortisol, we will have high amounts of eosinophils.
The above patient has adrenal insufficiency; therefore, there is a low cortisol level. In the above patient, there is low blood pressure because cortisol has presynaptic effects on vascular responsiveness to catecholamines (like norepinephrine). Low cortisol leads to blood vessels being less responsive to catecholamines, leading to a drop in vascular tone, which leads to hypotension.
Also, the patient has dark skin. Pro-opiomelanocortin (POMC) is a precursor to ACTH, MSH, and β-endorphin. Thus, in Adrenal Insufficiency, there is low cortisol, leading to negative feedback will leads to an increase in pro-opiomelanocortin (POMC), leading to more ACTH, MSH, and Beta-Endorphins.
❌ Choice A. Sodium is low, not high, due to low aldosterone, which is responsible for more ENAC channels in the principal cells of the collecting tubule.
❌ Choice B. Hilar Coin Lesion is lung cancer. This patient does not have lung cancer
❌ Choice C. This would be suppressed in Cushing's syndrome; this patient has adrenal insufficiency, hence it will not be the case
❌ D. Adrenal insufficiency, hence this patient will have an increased corticotropin-releasing hormone and an increased adrenocorticotropic hormone.
