The relationship between thyroid function and bone health in euthyroid healthy adult Nigerians

Abstract

There is a dearth of reports on variation in thyroid function within the reference range on bone health in euthyroid healthy adults in Nigeria This study evaluated the variation in thyroid function within reference range on biochemical bone markers and bone mineral density in healthy adults. This prospective study was carried out among 40 healthy participants above 21 years of age but less than 50 years by systematic random sampling. Exclusion criteria included subjects with acute or chronic disease states, previous fractures, any drug use, history of alcohol
or smoking. Interviewer –questionnaire was administered. Anthropometric indices determined. Blood samples for thyroid function tests included triiodothyronine (FT3), thyroxine(FT4), Thyroid Stimulating Hormone(TSH-thyrotropin), osteocalcin (OC), and Alkaline phosphatase (ALP), serum calcium adjusted for albumin, inorganic phosphorus, and urine sample for calcium and creatinine were collected after 10 - 12 hours fast. 24 hour calcium excretion was calculated (CaE). Bone mineral Density determined by Dual X - ray Absorptiometry scan. Statistical analysis done,< 0.05 set as level of significant. The mean age 34.10 years (7.8), with BMI 26.32kg/m² (4.02),waist circumference 76.60cm (17.07). The mean levels of bone markers were osteocalcin 17.68ng/ml (10.67), alkaline phosphatase70.60 IU/L (16.56) and 24hour calcium excretion 396.10mg/dl (101.89). OC and ALP inversely correlated with age but CaE did not. TSH positively correlates OC( r =0.35,p=0.029), but not CaE, p > 0.05. FT4 correlates bone formation markers OC,ALPand CaE p <0.05. Neither FT3,FT4 or TSH neither correlates with zscore BMD. Normal variation in the levels of ft4 and TSH has an early impact on biochemical bone markers compared to bone mineral density. Biochemical bone markers are thus suggested as screening tools for early detection of metabolic bone diseases in euthyroid healthy adults.

Keywords: Thyroid function, Bone Markers, Healthy Adults