牙槽骨骨密度与甲状腺激素的影响

Thyroid hormones affect alveolar bone density

背景:过量的甲状腺激素能使成骨细胞与破骨细胞的活性均增加,引起骨吸收与骨转化增强,但其中骨形成不能完全代偿骨吸收,最终致使骨量的丢失增加。目的:观察兔甲亢状态下牙槽骨骨密度的变化。方法:将24只新西兰大白兔分成2组,每组雌雄各半。甲亢组每日用左旋甲状腺素50μg/(kg·d)生理盐水稀释,腹腔注射,对照组每日注射等量生理盐水。8周后检测FT3,FT4,碱性磷酸酶,Ca,P,Mg指标;用双能X射线骨密度扫描仪检测腰椎、下颌骨及双侧股骨远心端骨密度,并进行相关性分析。结果与结论:在给药8周后,(1)甲亢组兔血清FT3,FT4明显高于对照组;(2)甲亢组血清碱性磷酸酶,Ca,P,Mg均高于对照组,其中甲亢组血Ca显著高于对照组(P<0.01);(3)甲亢组腰椎、下颌骨、左股骨、右股骨骨密度数值均显著低于对照组;(4)甲亢组下颌骨骨密度与椎骨和股骨的骨密度变化呈正相关;(5)结果说明,FT3,FT4数值变化满足甲亢诊断,骨密度数值变化满足骨质疏松诊断,甲亢状态下牙槽骨骨密度降低。

BACKGROUND：Overproduction of thyroid hormones is shown to increase the activities of osteoblasts and osteoclasts, stimulating bone resorption and transformation. Inadequate compensation of increased bone resorption by bone transformation results in an increased loss of bone mass. OBJECTIVE：To investigate the effects of hyperthyroidism on the density of the alveolar bone. METHODS：Twenty-four New Zealand rabbits were equal y randomized into hyperthyroidism group and control group. Rabbits in the hyperthyroidism group or control group were daily injected intraperitoneal y with 50μg/kg levothyrocine diluted in physiological saline solution or equal volume of physiological saline. At 8 weeks after treatment, serum levels of thyroid hormones （FT3 and FT4）, alkaline phosphatase, magnesium and calcium, phosphorus were determined;meanwhile, the bone densities of the lumbar vertebra, mandible, bilateral distal femur were determined by dual energy X-ray absorptiometry and the correlation analysis was performed. RESULTS AND CONCLUSION：At 8 weeks after treatment, serum levels of FT3, FT4, alkaline phosphatase calcium, phosphorus, and magnesium in the hyperthyroidism group were significantly increased （P〈0.01）, while the bone densities of the lumbar vertebra, mandible, bilateral distal femur were significantly decreased （P〈0.05）, compared with the control group. Bone density of the mandible was positively correlated with the bone density the lumbar vertebra and bilateral distal femur. These findings suggest that the changes in FT3 and FT4 are sufficient for the diagnosis of hyperthyroidism. Hyperthyroidism results in the decreased density of the alveolar bone, indicating the occurrence of osteoporosis.