Bone fractures among adult Nigerians with hyperthyroidism: risk factors, pattern and frequency

Abstract

Background: Hyperthyroidism is a common endocrine disorder with multi-systemic effects, the least reported of which is bone loss and fractures.
Objective: The aim was to evaluate the risk factors, pattern and frequency of bone fractures among Nigerians with hyperthyroidism.
Methodology: An analytical study was undertaken of 40 patients with hyperthyroidism aged between 21 and 50 years. They were seen at the outpatient Endocrine, Diabetic and Metabolism (EDM) clinic of Lagos State University Teaching Hospital (LASUTH). Using an interviewer-administered questionnaire, information on sociodemographics, medical history, clinical and biochemical parameters and dual-energy X-ray absorptiometry (DXA) scan was obtained. Risk of fracture was assessed using WHO and ISCD risk calculators. During statistical analysis, quantitative and qualitative data were expressed as mean (SD) and percentages.
Results: In all, 40 patients with hyperthyroidism were studied with a mean age of 36.16 (8.43) years. There were 32 females (80%, female:male ratio 4:1) and mean body mass index was 24.14 (4.3) kg/m. Hyperthyroidism was defined by Waynes’ scoring index greater than 19 and confirmed by elevated thyroid hormones (FT4 39.44 (24.11) (pmol/l), FT3 12.13 (7.83) (pmol/l)) and suppressed TSH 0.26 (0.03) (u/U/ml). Increased bone turnover was documented by elevated bone formation markers (osteocalcin 45.7 (19.9) ng/ml and alkaline phosphatase 221.1 (143.46 IU/l)), bone resorption markers (24-hour calcium excretion 590.95 (506.1) mg/day). The mean BMD T- and Z-scores were reduced –2.0 (1.2). Bone loss was observed in 31 (72.5%) hyperthyroid subjects, but only three (7.5%) had fractures due to minor trauma.
Conclusion: Bone fractures may not be uncommon in hyperthyroidism. Early screening for bone diseases should be encouraged to improve treatment outcome.