Bone mineral density in lumbar vertebrae 1-4 [(0.86 ± 0.14) g/cm 3], left femoral neck [(0.79 ± 0.07) g/cm 3] and left hip joint [(0.72 ± 0.10) g/cm 3] in the hyperthyroidism group was significantly lower than that in the control group [(1.28 ± 0.21) g/cm 3, (1.03 ± 0.18) g/cm 3, (0.86 ± 0.13) g/cm 3, t = 9.115, 6.806, 4.675, all P < 0.001]. There were 6 cases of osteoporosis, 12 cases of osteopenia and 12 cases of normal bone in the hyperthyroidism group. There was 1 case of osteoporosis, 6 cases of osteopenia and 23 cases of normal bone in the control group. There was significant difference in the number of cases developing osteoporosis between hyperthyroidism and control groups ( Z = 2.968, P < 0.05). Serum level of 25(OH)D in the hyperthyroidism group was significantly lower than that in the control group [(16.89 ± 4.31) μg/L vs. (24.13 ± 5.48) μg/L, t = 5.688, P < 0.001]. Serum levels of PINP and β-CTX in the hyperthyroidism group were significantly lower than those in the control group [PINP (49.37 ± 10.23) μg/L vs. (47.68 ± 6.49) μg/L; β-CTX (774.56 ± 159.67) ng/L vs. (534.32 ± 167.48) ng/L, t = 45.974 and 5.687, both P < 0.001]. In the hyperthyroidism group, bone mineral density at lumbar vertebrae 1-4, left femoral neck and left hip joint was positively correlated with serum level of 25(OH)D ( r = 0.417, 0.396, 0.401, all P < 0.05), and it was negatively correlated with serum levels of PINP and β-CTX ( r = -0.414, -0.399, -0.432, -0.404, -0.387, -0.412, all P < 0.05).