Bone Mineral Density and Metabolic Indices in Hyperthyroidism

Abstract

Hyperthyroidism can alter bone metabolism by increasing both bone resorption and formation. The increase in bone resorption predominates, leading to a decrease in bone mass. To assess the effect of hyperthyroidism on bone and mineral metabolism, we measured bone density using single photon absorptiometry in 30 untreated hyperthyroid patients. Patients were categorized into three groups based on sex and alkaline phosphatase levels: 44 sex-and agematched subjects were used as controls. Bone densities were significantly lower in all patient groups compared with controls. Alkaline phosphatase was found to be a useful marker for assessing severity of bone disease in hyperthyroid patients as there is significant correlation between the alkaline phosphastase level and degree of bone loss and decrease in bone density among patients with higher alkaline phosphatase value. Hyperthyroidism should be considered in the differential diagnosis of unexplained elevated alkaline phosphatase activity. Bone Mineral Density and Metabolic Indices in Hyperthyroidism. 1991; 11(5): 530-533 Thyroid disorders such as hyperthyroidism have profound effects on bone and mineral metabolism [1]. The skeletal changes in hyperthyroidism can be grouped into two main categories: first, localized changes in the fingers, consisting of periosteal hyperplasia leading to clubbing, a condition known as thyroid acropathy, which has been reported to occur in about 1% of the thyrotoxic patients; and second, a generalized loss of bone mass, taking the form of osteoporosis [2].There is a negative correlation between the duration of the disorder and the bone mass. Hyperthyroidism causes increased bone turnover leading to osteopenia and increased incidence of fracture [3].Both osteoblastic and osteoclastic activities are increased, with bone resorption exceeding bone formation.Bone biopsy usually shows decreased trabecular bone volume and increased cortical porosity [4]. Radiological signs of hyperthyroid bone disease vary between 3.5 and 50% [5], depending on the severity of the disease as well as on the observer, as it is a purely subjective assessment. Bone densitometry devices are used in assessing hyperthyroid bone disease and these often detect the skeletal complications that accompany hyperthyroidism, even when biochemical or radiological evidence of bone disease is absent [6].Single photon absorptiometry (SPA) is used to assess appendicular bones only, as tissue composition surrounding the bone mass has to be uniform and minimal. The method was based on the principle described by Cameron et al [7]. SPA was used in this study to examine the effect of hyperthyroidism on bone metabolism.

Differences in Clinical and Laboratory Findings Among Graves’ Disease, Painless Thyroiditis and Subacute Thyroiditis Patients With Hyperthyroidism

“…Serum ALP level in Graves' disease was significantly higher than in painless thyroiditis. This may reflect an increased bone and mineral metabolism due to hyperthyroidism [26,27]. Serum CRP level was significantly higher in subacute thyroiditis than in Graves' disease, which is consistent with that elevation of CRP is included in the guideline of diagnosis for subacute thyroiditis by the Japan Thyroid Association.…”

Clinical, Biochemical, Hematological, Endocrinological and Immunological Differences Between Graves’ Disease Patients With and Without Thyroid Storm

“…Serum ALP level in TS patients was significantly higher than patients without TS. This may reflect an increased bone and mineral metabolism due to hyperthyroidism [10, 11]. Otherwise, this may reflect GI/hepatic manifestation in TS, which was supported by non-significantly elevated total bilirubin levels in TS [3].…”