Change Of Bone Mineral Density In The Patients With Hyperthroidism

Objective: Hyperthyroidism is a disease caused by excess thyroxine secretion from thyroid gland. There are studies shown that hyperthyroidism can lead to the change of bone mineral density (BMD) and even causes osteoporosis. Osteoporosis (OP) is a kind of common disease.It has become a more and more severe problem in the whole world. Every year there are millions of osteoporotic patients may undergo fracture and disability, which increase social and economic burden. The present study is aimming to discuss the alterations in bone mineral density in hyperthyroidism patients. The effect of thyroid gland on bone mineral density will be discussed and prevention strategy should be taken to avoid risk to fracture.Methods: A total of 102 subjects were included. There were 50 female patients in the hyperthyroidism group (A), which were divided into two subgroups: 24 pre-menopausal patients (A1) aged 34～50 years old (41.3±5.96) years old and 26 post-menopausal patients (A2) aged 51～75 years old (60.53±8.01) years old. The disease course was from 1 to 5 years (3.08±1.74) years and all patients took medicine.52 healthy women were chosed as control group (B): which were also divided into two subgroups including 25 pre-menopausal healthy women (B1) aged 34～49 years old (42.00±5.45) years old and 27 post-menopausal healthy women (B2) aged 52～72 years old (60.11±8.23) years old. Height, weight of all subjects were measured and body mass index (BMI) was calculated. Height, weight ,BMI, age and menopausal years (MPY) of all subjects were recorded carefully. Disease course and therapy condition in the hyperthyroidism group were also recorded. The level of blood free triiodothyronine (FT3), free tetraiodothyronine (FT4) and thyroid-stimulating hormone (TSH) in all groups were measured. BMD at L2-L4 lumbar vertebrae, femur (neck, ward triangle, trochanter, InterTro) were measured by DEXA (dual energy X-ray absorptiometry).Results:1 Compared with control group, the level of blood free triiodothyronine (FT3) and free tetraiodothyronine (FT4) in hyperthyroidism group was significantly higher while thyroid-stimulating hormone (TSH) was significantly lower (P<0.05).2 There were no differences in age and BMI between hyperthyroidism and control group (P>0.05). The BMD at lumbar spines, femoral neck, Ward,s triangle, trochanter and inter trochanter in pre-menopausal patients with hyperthyroidism were lower than in pre-menopausal healthy women, especially at lumbar spines, femoral neck, Ward,s triangle, and inter trochanter, BMD were decreased more significantly(P<0.05).3 There were no differences in age, BMI and menopausal years (MPY) between post-menopausal patients in hyperthyroidism group and post-menopausal healthy women in control group (P>0.05). The BMD at lumbar spines, femoral neck, Ward,s triangle, trochanter and inter trochanter in post-menopausal patients in hyperthyroidism group were all lower than that at post-menopausal healthy women, especially at lumbar spines, trochanter, and inter trochanter, BMD were decreased more significantly(P<0.05).4 In subjects with hyperthyroidism, there were no differences in FT3, FT4, TSH levels, course and BMI between pre-menopausal and post-menopausal subjects (P>0.05).The difference in age between the two groups was significant(P<0.05).The BMD at lumbar spines, femoral neck, Ward,s triangle, trochanter and inter trochanter in post-menopausal subjects were significantly decreased (P<0.05).5 In healthy subjects, there were no differences in FT3, FT4, TSH and BMI between pre-menopausal and post-menopausal group (P>0.05).The age between the two groups was significantly different(P<0.05).The BMD at lumbar spines, femoral neck, Ward,s triangle, trochanter and inter trochanter in post-menopausal healthy women were significantly decreased than pre-menopausal controls(P<0.05).6 For the BMD measured at lumbar spines, femoral neck, Ward,s triangle, trochanter and inter trochanter, post-menopausal patients with hyperthyroidism had lowest BMD while pre-menopausal healthy women had highest.7 The L2-L4 BMD in patients with hyperthyroidism was not significantly correlated with FT4, but negatively correlated with FT3 and was positively correlated with TSH. The mean femoral BMD in patients with hyperthyroidism was not significantly correlated with FT4 , but negatively correlated with FT3 and was positively correlated with TSH levels.8 Data from standard regression coefficient (Bata) had indicated that, L2-L4, the mean femoral BMD in patients with hyperthyroidism were correlated with age, MPY, BMI, course, FT3 and TSH, but not with FT4.Conclusions:1 Hyperthyroidism can lead to loss of bone mass and decrease of bone mineral density.2 Menopause can also cause decrease of bone mineral density.3 Post-menopause with hyperthyroidism led to significantly reduce bone mineral density.4 The BMD in patients with hyperthyroidism were closely related with age, MPY,TSH, course, FT3 and BMI but not with FT4.