Parathormone-25(OH)-vitamin D axis and bone status in children and adolescents with type 1 diabetes mellitus

Background: Skeletal involvement in patients with type 1 diabetes mellitus (T1DM) has complex pathogenesis and despite numerous researches on this problem, many questions remain unanswered. Objective: This study aimed to assess bone status by measurement parathormone (PTH), 25-hydroxy vitamin D [25(OH) D] serum levels in children and adolescents with T1DM and its relation to insulin-like growth factor-1 (IGF-1), disease duration, puberty stage, and metabolic control. Patients and methods: This study included 36 children and adolescents with T1DM and 15 apparently healthy controls. Serum levels of 25(OH) D, PTH, IGF-1 measured using enzyme-linked immunosorbent assay (ELISA), while glycosylated hemoglobin (HbA1c), calcium (Ca), inorganic phosphorus (PO4) using autoanalyzer. Bone quality assessed using dual energy X-ray absorptiometry (DEXA). Results: Diabetic patients showed significant increase in PO4 and PTH levels, while significant decrease in Ca, IGF-1, and 25(OH) D serum levels. As much as 52.8% of patients showed reduced 25(OH) D, and 30.65% showed elevated PTH serum levels. In diabetic patients, abnormal bone status (osteopenia-osteoporosis) found mostly in total body (94.40%) then lumber-spine (88.90%), ribs (88.90%), pelvis (86.10%), thoracic-spine (80.60%), arms (80.60%) and legs (77.80%), while head bones showed no abnormalities. Long diabetic duration had negative; meanwhile PTH, onset age, and puberty age had positive impact on bone status. Conclusions: Children and adolescent with T1DM have abnormal bone status mostly in axial skeleton which may be contributed to impairment of formation of 25(OH) D and IGF-1. Physical activity, calcium and vitamin D supplement seem important in T1DM. Elevated serum PTH level in diabetic patients is not uncommon and its positive correlation with bone status needs further investigations.