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For patients with adrenal incidentaloma, high-resolution peripheral quantitative computed tomography (HR-pQCT) can be used to assess negative effects on bone, which are most likely secondary to subclinical hypercortisolism, according to study data published in The Journal of Clinical Endocrinology & Metabolism.
Although most adrenal incidentalomas are classified as nonfunctioning, up to 40% of cases may be associated with autonomous cortisol secretion, also known as subclinical hypercortisolism. Previous studies have suggested an increased risk for abnormalities in bone mineral density (BMD) and vertebral fractures in patients with autonomous cortisol secretion.
The goal of the current study was to assess areal BMD (aBMD), bone microstructure, and fracture occurrence in patients with adrenal incidentaloma using multiple imaging techniques.
The study cohort included 45 patients with nonfunctioning adrenal incidentaloma, defined as serum cortisol level ≤1.8 µg/dL after a 1-mg dexamethasone suppression test, and 30 patients with autonomous cortisol secretion, defined as serum cortisol level between 1.9 and 5.0 µg/dL after the same test. Assessment of aBMD was based on dual-energy x-ray absorptiometry; vertebral fracture was assessed by spine x-ray; and bone geometry, volumetric BMD (vBMD), and microstructure were assessed by HR-pQCT.
Patients with autonomous cortisol secretion showed lower aBMD and lower BMD z score values at the spine, femoral neck, and radius 33%, as well as lower values of trabecular bone parameters at the distal radius compared with patients with nonfunctioning adrenal incidentaloma. Osteoporosis was very common in both groups, with a prevalence of 64.9% in individuals with nonfunctioning adrenal incidentaloma and 75% in those with autonomous cortisol secretion (P =.55).
In multivariate analysis, autonomous cortisol secretion maintained an association with lower aBMD at the femoral neck (P =.02) and radius 33% (P =.01), as well as with lower BMD z score at lumbar spine (P =.02) and femoral neck (P =.02).
Compared with patients with nonfunctioning adrenal incidentaloma, several trabecular bone parameters measured at the distal radius were significantly lower in patients with autonomous cortisol secretion. These associations were significant for density parameters (trabecular vBMD, especially at the inner zone) and microstructure (trabecular bone volume to tissue volume and trabecular thickness). In addition, there was a correlation between cortisol levels after 1-mg dexamethasone suppression test and the ratio of the outer to inner zone of the trabecular region vBMD, but not with any other HR-pQCT parameters.
There was no significant difference between the groups in the number of patients with clinical nonvertebral fractures and with morphometric vertebral fractures on x-rays.
The study had several limitations, including the small sample size, lack of a control group, and no assessment of cortical porosity or bone strength by finite element analysis.
“[A] minimal alteration in the hypothalamic-pituitary-adrenal axis, as evidenced in patients with [autonomous cortisol secretion], may be sufficient to cause a negative impact on bone health,” wrote the researchers.
Reference
Moraes AB, de Paula MP, Paranhos-Neto FP, et al. Bone evaluation by high-resolution peripheral quantitative computed tomography in patients with adrenal incidentaloma [published online May 15, 2020]. J Clin Endocrinol Metab. doi:10.1210/clinem/dgaa263
