Abstract

Hyperthyroidism is convoyed by osteoporosis or osteopenia with increased rates of bone formation and predominance with bone resorption. Thyroid disease is a common and important health problem in Bangladesh. Thyroid hormones are necessary for normal skeletal growth, maturation, basic metabolism, and bone turnover. There is inadequate awareness about the hyperthyroid bone disease which further reduce quality of life. Therefore there is a great need to evaluate bone mineral density in hyperthyroid patient, so that early diagnosis of low bone mass or osteoporosis can be made. So this study would be beneficial to find out the profile of bone involvement in overt hyperthyroidism by BMD measurement and thereby reducing or avoiding bone pain and osteoporotic fracture risk in hyperthyroidism.

Objective: This study aimed to assess the profile of bone involvement in overt hyperthyroidism by measuring bone mineral density in respective of age and sex.

Study Design: Observational study.

Place of study: Medicine department of Khulna Medical College Hospital.

Period of study: The study was conducted among the indoor patients of medicine wards Khulna Medical College Hospital, Bangladesh from June, 2013 to December, 2013.

Study Population: 35 patients, diagnosed as Hyperthyroidism both clinically and biochemically.

Method and Materials: This was an observational study. The patients had been treated with radioiodine and antithyroid drug were excluded. All other secondary causes of low BMD like type-I diabetes mellitus, liver and kidney disease, history of drug intake like long term steroid intake were also excluded. The age of the patients ranged from 25 to 40 years. Both male and female were included. BMD of each study population was measured by Lunar DXA scanner at both lumbar spine and femoral neck regions.  Low BMD was defined according to World Health Organization (WHO) criteria. The T-score was considered as BMD parameter and was expressed as either osteoporosis or osteopenia with the rest being in normal group.

Result: Among total patients 35, 13 (37.1%) were male and 22 (62.9%) were female. Ratio was 1:1.9. Majority were in older age (31-40 years) compared to younger age (25-30 years), percentage being 71.4% vs. 28.6%. BMD was expressed in absolute value (gm/cm²) and T score. Low BMD was found at both femoral neck (16/35, 45.7%) and lumbar spine (24/35, 68.6%). According to WHO classification, 3 (23.1%) male and 6 (27.3%) female had osteoporosis, whereas 5 (38.5%) male and 10(45.5%) female had osteopenia in lumbar spine. At femoral neck, 2 (15.4 %) male and 3 (13.6%) had osteoporosis, whereas 5 (38.5%) male and 6 (27.3%) female were osteopenia. These difference between male and female was not statistically significant at any site of measurement (p value >0.05). In this study, younger age group had more bone loss compared to older age group at both lumbar spine and femur neck. Low BMD level at neck femur region was statistically significant in younger age group (p value < 0.05%). Considering T-Score, 80% of younger population had either osteoporosis or osteopenia (osteoporosis-40% and osteopenia-40%) at lumbar spine compared to 64.0% in older age group (osteoporosis 20% and osteopenia 44%). At femoral neck, 60% of younger study population and 40% of older population had bone involvement (younger group: osteoporosis vs. osteopenia = 30% vs. 30%; older group: osteoporosis vs. osteopenia = 08% vs. 32%). T-score at femoral neck of male (-1.22±1.19) indicate higher incidence of osteopenia compared to female (-0.79±1.17).On the other hand, osteopenia was found to be more severe in female patients compared to the male at lumbar spine (T-score: male vs. female =-1.43± 1.23 vs. -1.65±1.46). This observation also was not statistically significant.

Conclusion: Hyperthyroidism has more impact on younger age when the peak bone mass is achieved and femur neck region may be more affected area. Bone loss is occurred in both spine and hip irrespective of sex. BMD measurement should be a routine procedure in hyperthyroid patients.