Low levels of some hormone receptors in patients with subclinical Cushing’s syndrome and in those with a type of adrenal gland tumor called pheochromocytoma, all with abnormal hormone levels in their blood, were linked to weight gain and obesity, a risk factor for cardiovascular and other diseases.
Increases in hormone levels were not seen in these patients.
The study, “Expression of adiponectin and leptin receptors in adrenal incidentaloma patients with subclinical hormone secretion,” was published in the journal Cancer Biomarkers.
The hormone receptors studied were adiponectin receptors – Adipo R1, Adipo R2 – and the leptin receptor. The first are involved in promoting the consumption of glucose and fat by enhancing activity of the hormone adiponectin. Leptin Ob-R is responsible for promoting activity of a hormone called leptin that regulates hunger.
Researchers set out to discover whether high hormone levels in tumors of the adrenal glands – hormone-producing glands located above the kidneys – are associated with abnormal levels of these hormone receptors.
While this was not the case, a high body mass index (BMI) was tied to low receptor levels. Body mass index is a quick screening tool for assessing health risk based on a person’s height and weight. A healthy BMI range for adults is 18.5 to 24.9.
The investigators compared BMI values and the levels of Adipo R1, Adipo R2, and leptin Ob-R in the adrenal tumors removed from 38 patients with subclinical Cushing’s syndrome (SCS), 40 with pheochromocytoma (PHEO) – a tumor that produces excess catecholamine and increases blood pressure – and a control group of 42 patients with tumors in the adrenal gland but normal hormone activity. The average age was 53.3.
The average BMI was 27.1 in SCS patients and 25.8 in PHEO patients. It was 26.8 in the control group. In the case of subclinical Cushing’s syndrome, levels of all three receptors dropped as BMI increased. Only low levels of Adipo R2 receptors were associated with increased BMI in patients with PHEO.
While adiponectin receptors are mostly produced by the adipose (fat) tissue, normal adrenal glands and adrenal tumors may also produce these receptors. Serum samples of 12 patients showed that only Adipo R1 levels correlated with adiponectin levels in the blood.
“[Being] overweight and obesity are key in regulating hormonal activity of the adipose tissue. Our data suggest that adiponectin and leptin receptors expression in human adrenal tumors is mainly associated with BMI,” the researchers concluded.