Prevalence and phenotype of primary bilateral macronodular adrenal hyperplasia with autonomous cortisol secretion: a study of 98 patients

Aim: This study evaluated prevalence of primary bilateral macronodular adrenal hyperplasia (PBMAH). It also analyzed the differential phenotype of patients with PBMAH compared to other bilateral adrenal lesions that do not meet the definition of PBMAH.

Methods: We reviewed the medical records of 732 patients diagnosed with an adrenal incidentaloma at our center. Ninety-eight patients with subclinical hypercortisolism were included in the analysis. We defined PBMAH as the presence of plasma cortisol > 1.8 μg/dL after an over-night 1-mg dexamethasone test, bilateral adrenal hyperplasia, and bilateral adrenal nodules > 1 cm.

Results: A total of 31 patients had PBMAH. Patients with PBMAH showed greater prevalence of autonomous cortisol secretion (plasma cortisol > 5.0 μg/dL after an overnight 1-mg dexamethasone test) than patients without PBMAH (OR 4.1, 95%CI 1.38-12.09, p = 0.010). Tumor size and total adenomatous mass were significantly greater in patients with PBMAH compared to patients without PBMAH (30.2 ± 12.16 vs. 24.3 ± 8.47 mm, p = 0.010 and 53.9 ± 20.8 vs. 43.3 ± 14.62 mm, p = 0.023), respectively. A greater proportion of patients with PBMAH had diabetes compared to patients without PBMAH (45.2% vs. 25.4%, p = 0.05).

Conclusion: PBMAH is present in one-third of patients with adrenal incidentaloma and subclinical hypercortisolism. Patients with PBMAH showed greater autonomous cortisol secretion, bigger tumor size, and higher rates of diabetes than those without PBMAH.