Bone Mineral Density in β Thalassemia Major and Intermedia, Correlation with Biochemical and Hormonal Profiles

Background: Expansion of bone marrow cavity and decreased cortical and trabecular bone tissues and osteoporosis are resulted from beta-thalassemia. The aim of this study was to assess bone mineral density (BMD) in patients with β thalassemia major and intermedia, and to determine their biochemical and hormonal profiles that may affect BMD. Materials and Methods: In a cross sectional study from October 2004 to April 2006, 305 patients (273 thalassemia major [137 males and 136 females] and 32 thalassemia intermedia [13 males and 19 females]) were evaluated for BMD. Dual x-ray absorptiometry was performed at 3 sites: spine (L2-L4), femoral neck, and radius. Z score< -2.5 was considered as osteoporosis, and between -1 and -2.5 as osteopenia. Z-scores were calculated according to bone density values based on age and sex. Patients were grouped according to age 3-6, 6-10, 10-13, 13-16, and over 16 years old. The stage of puberty was determined according to Tanner staging and its progression was followed. Biochemical and hormonal profiles of patients were recorded. Results: In thalassemia major, mean age was 14 ± 6.5 years, and mean BMD Z-score of spine, radius and hip were - 2.3 ± 0.9, -2.8 ± 1.2, and -1.9 ± 1.4, respectively. Mean age of patients with thalassemia intermedia was 13.4 ± 6.2 years, and the mean Z-score of spine, radius, and hip were -2.1 ± 0.9, -2.0 ± 1.3, and -2.3 ± 1.3, respectively. Hypogonadism was detected in 36% of thalassemia major and 35% of thalassemia intermedia but hypothyroidism, diabetes mellitus, and hypoparathyroidism were detected only in thalassemia major with frequency of 2.8%, 1.8%, and 1.2%, respectively. BMD in spine and radius were significantly lower in patients with hypogonadism than in patients with normal puberty (P=0.039 and P=0.015, respectively). Height Standard Deviation Score (HSDS) was not significantly different in groups of osteoporosis and normal. Osteoporosis was seen in all age groups, and was more common in males than females at spine and radius bones (P<0.001). It was less common in patients with hypothyroidism, hypoparathyroidism, and diabetes mellitus. BMD Z-Score had significant correlation with serum ferritin only in radius area (P=0.04), and it had no significant correlation with serum Ca, P, Mg and Zn. Conclusion: Our results showed that the patients with thalassemia major and intermedia had low BMD. Patients with hypogonadism and males had lower BMD. Young children also had low bone mass, so early attention is essential.