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A case of ACTH-independent bilateral macronodular adrenal hyperplasia and severe congestive heart failure
Insights
This study details a unique case of Cushing's syndrome (CS) caused by bilateral macronodular adrenal hyperplasia (AIMAH). Aberrant adrenal receptors, potentially linked to heart failure, led to increased cortisol secretion.
Area of Science:
- Endocrinology
- Cardiology
- Molecular Biology
Background:
- ACTH-independent bilateral macronodular adrenal hyperplasia (AIMAH) is a rare cause of Cushing's syndrome (CS).
- AIMAH pathogenesis involves aberrant adrenal receptors mediating abnormal hormone secretion.
- Congestive heart failure (CHF) can activate the renin-angiotensin system, increasing angiotensin II (AT-II) levels.
Observation:
- A patient with CS due to AIMAH and severe Class IV CHF presented with abnormal responses to ACTH and postural changes.
- Clinical testing suggested aberrant adrenal receptors for ACTH, vasopressin, catecholamines, or AT-II.
- Adrenal tissue analysis revealed an eight-fold increase in melanocortin 2 receptor (MC2-R) expression.
Findings:
- Increased MC2-R expression correlated with elevated cortisol and aldosterone following ACTH administration.
- The study proposes that severe CHF-induced AT-II elevation may have upregulated MC2-R expression.
- This suggests a novel mechanism linking CHF, AT-II, and AIMAH development.
Implications:
- This case may elucidate a previously unrecognized pathway for AIMAH development in CS.
- Understanding aberrant receptor function in AIMAH could lead to targeted therapies.
- The interplay between cardiac function and adrenal steroidogenesis warrants further investigation.
Abstract:
Cortisol secretion in ACTH independent bilateral macronodular adrenal hyperplasia (AIMAH) can be regulated by aberrant adrenal receptors. We describe a patient with Cushing's syndrome (CS) due to AIMAH and concomitant Class IV congestive heart failure (CHF). Clinical testing for the presence of aberrant receptors revealed a pronounced serum cortisol (257%) and aldosterone response (212%) to the administration of ACTH and a partial serum cortisol (35%) and aldosterone (106%) response to upright posture. This suggested the possible presence of aberrant hormone receptors for ACTH [melanocortin 2 receptor (MC2-R)], vasopressin, catecholamines or angiotensin II (AT-II) on the patient's adrenal glands. Adrenal tissue from the patient demonstrated an eight-fold increased expression of MC2-R compared to normal adrenal tissue. This increased expression was consistent with the increase in cortisol and aldosterone seen in response to exogenous ACTH. We propose that the severe CHF resulted in activation of the renin-angiotensin system, with an increased production of AT-II. The elevated circulating levels of AT-II may have led to increased expression of MC2-R on the patient's adrenal glands and increased responsiveness to ACTH. This unusual case of CS may elucidate a heretofore unknown mechanism for the development of AIMAH.
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