Endocrine Abstracts

Context: Several studies have shown that Trabecular Bone Score (TBS) predicts fractures independently of Bone Mineral Density (BMD) measured with Dual Energy X-ray Absorptiometry (DXA), even in patients with Primary Hyperparathyroidism (PHPT), known to have deteriorated bone microarchitecture. Low TBS values alone are still not considered as a single criterium to recommend parathyroid surgery. Measuring bone quality in patients with PHPT may be helpful to identify a proportion of patients at increased fracture risk regardless of the other known criteria used to recommend parathyroidectomy.

Objective: To describe the prevalence of low bone quality measured by TBS in a cohort of patients diagnosed with PHPT to evaluate its impact on the clinical management of PHPT.

Design: Cross-sectional, observational.

Setting: Academic.

Patients: From February 2021 to January 2023, 133 patients with asymptomatic classical PHPT (i.e. with elevated total, albumin adjusted, or ionized serum calcium) were consecutively evaluated. All patients underwent complete serum and urinary assessment in the same laboratory, bone density test with TBS by using the same DXA machine, and renal ultrasound to screen for nephrolithiasis or nephrocalcinosis. We selected 119 patients who had a DXA performed at all 3 sites along with TBS. We retrospectively applied to each patient the recently revised criteria for parathyroid surgery as per the V International Workshop.

Main outcome measures: TBS, BMD, and biochemistries. TBS <1.200 was used to discriminate low bone quality.

Results: Mean age of the patients was 67±12 years and most were women (102/119, 85.7%). TBS was low in 34/119 patients (28.6%) with PHPT. Patients met the criteria for parathyroid surgery respectively due to hypercalcemia (>1 mg/dl above the upper normal limit) (16/119, 13.4%), hypercalciuria (>250mg/day for females or >300mg/day for males) (53/119, 44.5%), any previous clinical fragility fracture or morphometric vertebral fracture (28/119, 23.5%), reduced GFR (<60ml/min) (19/119, 15.9%), age less than 50 years (8/119, 6.7%), nephrolithiasis (20/119, 16.8%). Among the 29 patients not meeting any surgical criteria, 3 (10.3%) had low TBS. Among those with BMD T-score above -2.5 at all three sites, TBS was reduced in 6/48 (12.5%) patients. Lower TBS was associated with increasing age and lower BMD T-scores, with a strong association with osteoporosis at 1/3 distal radius (Odds-Ratio: 3.98, P=0.001).

Conclusions: By implementing routine TBS measurement, an estimated additional 10% of patients, who would otherwise not meet the current listed surgical recommendations, could benefit from curative parathyroid surgery to reduce fracture risk.