Impairment of Bone Mineral Density in Pituitary Thyrotropin-Secreting Adenomas: A Retrospective, Controlled Study

Hyperthyroidism can harm bone health, though it is seldom reported in thyroid-stimulating hormone/thyrotropin (TSH)-secreting adenomas (TSHomas). This study assessed bone mineral density (BMD) and bone turnover markers (BTMs) in TSHoma patients versus euthyroid controls and evaluated the impact of surgical treatment on bone metabolism.

We retrospectively reviewed 85 TSHoma patients who underwent BMD tests. Of these, 71 had baseline BMD data and were matched with 71 euthyroid healthy controls by age, sex, and body mass index. BMD and BTMs were measured.

TSHoma patients demonstrated significantly reduced BMD compared to matched euthyroid controls across all skeletal sites, with reductions of 12.4% at the lumbar spine (1.06 ± 0.19 vs 1.21 ± 0.14 g/cm², P < .001), 8.5% at the femoral neck (0.86 ± 0.14 vs 0.94 ± 0.11 g/cm², P < .001), and 14.8% at the total hip (0.86 ± 0.13 vs 1.01 ± 0.12 g/cm², P < .001). Baseline BTMs revealed elevated osteoblastic (procollagen type 1 N-terminal propeptide 108 [60, 202] ng/mL) and osteoclastic markers (β-CTX 0.84 [0.62, 1.30] ng/mL). Besides, free triiodothyronine showed strong positive correlations with BTMs: alkaline phosphatase (r = 0.45, P = .005), β-CTX (r = 0.61, P < .001), and procollagen type 1 N-terminal propeptide (r = 0.73, P = .004). Following tumor resection, BTMs decreased significantly: alkaline phosphatase (91 [74.25, 119.5] to 71 [68, 94] U/L, P = .003) and β-CTX (0.75 [0.57, 0.94] to 0.22 [0.21, 0.45] ng/mL, P = .008). Postoperative BMD revealed stabilization with nonsignificant improvements at all measured skeletal sites.

TSHoma patients exhibit significant BMD deficits compared to euthyroid controls. Surgery effectively reduces BTMs while stabilizing BMD, preventing further deterioration rather than restoring bone density.