Adrenocorticotropic hormone independent macronodular adrenal hyperplasia
- 1Middlemore Hospital, Auckland, New Zealand
- 2Tauranga Hospital, Tauranga, New Zealand
- 3Waikato Hospital, Hamilton, New Zealand
- Correspondence to Dr Peter Mwamure,
Figure 1 is of a CT scan showing bilateral macronodular adrenal glands in a patient with adrenocorticotropic hormone-independent macronodular adrenal hyperplasia (AIMAH).
AIMAH was first described in 19641.
AIMAH is often discovered as a fortuitous radiological finding, as in our patient, or during investigation for endogenous hypercortisolism. AIMAH represents less than 1% of patients with endogenous Cushing’s syndrome.
Most AIMAH patients are diagnosed in the fifth and sixth decades.
CT imaging normally shows bilateral adrenal nodules, which sometimes grow to as large as 5 cm, often with a combined adrenal weight of more than 60 g2. Although recent AIMAH data suggest that larger adrenal nodules accumulate an increased number of genomic and transcript abnormalities,3 AIMAH is a benign process that has so far not been shown to become malignant.
The secretion of cortisol in most patients with AIMAH is under the influence of hormones other than adrenocorticotropic hormone, which stimulate aberrantly expressed receptors in the adrenal glands.2 Examples include G-protein coupled receptors for glucose-dependent insulinotropic peptide, β-adrenergic receptors, vasopressin (V2, V3) receptors, serotonin (5-hydroxytryptamine) receptors and leptin receptors.
La Croix has described useful protocols for identifying various aberrant receptors as well potential medical treatment options.2 Treatment for AIMAH includes specific blockade of aberrant receptors where applicable. When specific blockade of aberrant receptors is not possible, unilateral adrenalectomy is recommended in those patients with moderate steroid hormone excess. In patients with very high levels of steroid hormone production, bilateral adrenalectomy is the treatment of choice.