Endocrine Abstracts

Medullary thyroid cancer (MTC) is a rare malignancy of the thyroid gland. MTCs originate from thyroid-C cells and account for 2-4% of all thyroid neoplasms. Originating from thyroid-C cells, the main secretory product of MTCs is calcitonin, used as sensitive and specific MTC-biomarker. Calcitonin is a hormone known to participate in calcium-bone metabolism suppressing bone-resorption by inhibiting the activity of osteoclasts, and inhibiting the kidney reabsorption of calcium and phosphorus. Despite these well recognized effects, little is known about skeletal health of patients affected by MTCs. Vertebral Fractures (VFs) are one of the most relevant clinical manifestations of skeletal fragility. To date, no data are reported in literature about VFs prevalence in patients affected by MTCs. The aim of our study was to investigate the VFs prevalence in patients with MTCs and in control-matched patients. VFs were detected on lateral chest X-rays using a qualitative and quantitative evaluation of vertebral shape. X-rays were performed prior the thyroid surgical treatment in MTCs patients and at hospitalization for infectious respiratory disease in control patients. MTCs and control patients were matched in a 1:1 ratio for age, sex and comorbidities, excluding those with comorbidities and therapies influencing bone metabolism. Sixty-two patients were included in the study, 31 affected by MTCs and 31 in control group. Median (IQR) age was 51 (38-66) years and 24 were male (38.7%). No statistical differences regarding age and sex were observed between the MTCs and control groups (P=0.84,P=1, respectively). VFs were detected in 9 (29%) MTCs patients and 2 (6.5%) control patients (P=0.043). In MTCs group, no statistical difference was observed regarding age between patients with and without VFs (P=0.27), and VFs were observed more frequently in male patients compared to female (50% vs 16%,P=0.044). No statistical associations were found between calcitonin levels and VFs occurrence. For the first-time to our knowledge, we have reported a high prevalence of VFs in patients affected by MTCs. It can be hypothesized that constantly elevated calcitonin levels directly or indirectly through changes in other parameters of bone metabolism may negatively impacts skeletal health.