Examkin

Question

Difficulty: MediumEndocrinology and Metabolism

Match each clinical presentation of suspected adrenal or pituitary pathology with the most appropriate initial diagnostic or screening test.

  • A 38-year-old man with resistant hypertension, muscle cramps, and a serum potassium of 2.9 mEq/L.Calculation of plasma aldosterone concentration to plasma renin activity ratio
  • A 44-year-old woman with paroxysmal palpitations, severe headaches, diaphoresis, and a blood pressure of 190/115 mm Hg.Measurement of plasma free metanephrines
  • A 32-year-old woman with rapid weight gain, proximal muscle weakness, facial plethora, and wide, purplish abdominal striae.Measurement of 24-hour urine free cortisol or overnight 1-mg dexamethasone suppression test
  • A 27-year-old man with profound fatigue, anorexia, weight loss, orthostatic hypotension, and hyperpigmentation of the buccal mucosa.Measurement of early morning serum cortisol and cosyntropin stimulation test

Answer

The presentations match their respective screening tests based on the suspected underlying hormonal excess or deficiency: primary hyperaldosteronism matches the aldosterone to renin ratio, pheochromocytoma matches plasma free metanephrines, Cushing syndrome matches 24-hour urine free cortisol, and primary adrenal insufficiency matches the morning cortisol with cosyntropin stimulation test.
Each clinical vignette presents classic hallmark signs of a specific adrenal disorder. Primary hyperaldosteronism presents with hypertension and hypokalemia and is screened with an aldosterone-to-renin ratio. Pheochromocytoma presents with episodic headaches, diaphoresis, and palpitations, and is screened with plasma free metanephrines. Cushing syndrome presents with hypercortisolism signs (striae, proximal weakness) and is screened with a 24-hour urine free cortisol or dexamethasone suppression test. Primary adrenal insufficiency presents with hypotension, fatigue, and hyperpigmentation, and is diagnosed using a cosyntropin stimulation test.

Step-by-Step Solution

1
Analyze the first clinical presentation (hypertension, hypokalemia) to identify the suspected diagnosis.
The suspected diagnosis is primary hyperaldosteronism (Conn syndrome).
Excess aldosterone causes sodium retention (hypertension) and renal potassium wasting (hypokalemia).
2
Select the appropriate screening test for primary hyperaldosteronism.
Plasma aldosterone concentration to plasma renin activity ratio.
Autonomous aldosterone production suppresses renin, resulting in an elevated aldosterone-to-renin ratio.
3
Analyze the second presentation (paroxysmal palpitations, severe headaches, diaphoresis, hypertension).
The suspected diagnosis is pheochromocytoma.
These are the classic symptoms of catecholamine excess.
4
Select the appropriate screening test for pheochromocytoma.
Measurement of plasma free metanephrines.
Metanephrines are the continuously released metabolic byproducts of catecholamines from the tumor.
5
Analyze the third presentation (central obesity, proximal muscle weakness, wide striae).
The suspected diagnosis is Cushing syndrome (hypercortisolism).
These physical findings are specific for excessive tissue exposure to glucocorticoids.
6
Select the appropriate screening test for Cushing syndrome.
Measurement of 24-hour urine free cortisol or overnight 1-mg dexamethasone suppression test.
These tests assess for an inappropriate elevation in cortisol production or a lack of expected suppression.
7
Analyze the fourth presentation (fatigue, hypotension, mucosal hyperpigmentation).
The suspected diagnosis is primary adrenal insufficiency (Addison disease).
Loss of cortisol and aldosterone causes fatigue and hypotension; loss of cortisol removes negative feedback on ACTH, leading to high ACTH and MSH (causing hyperpigmentation).
8
Select the appropriate screening test for primary adrenal insufficiency.
Measurement of early morning serum cortisol and cosyntropin stimulation test.
Cosyntropin (synthetic ACTH) should normally stimulate cortisol production; failure to do so confirms adrenal insufficiency.

Key Concept

Recognition of classic adrenal pathology syndromes and selection of their respective initial screening laboratory tests.
Estimated Time:1m 30s
Rate this question

Topics

Endocrinology and Metabolism

More questions from this topic