Predictors of abnormal bone mass density in adult patients with homozygous sickle-cell disease.

Background: Adult patients with sickle-cell disease (SCD) often have multiple bone compactions causing tissue hypoxia and osteonecrosis. The impact on bone abnormalities lesion detected by bone mass density is not well defined.

Aim: The study is a cross sectional, perspective was designed to assess the prevalence of abnormal BMD in adult Bahraini patients with SCD and to assess the predictive risk of different metabolic variables such as serum level of vitamin D3, testosterone, and parathyroid hormone in addition to lactate dehydrogenase (LDH), hemoglobin (Hb), and reticulocyte count for the development of abnormal bone density on dual X-ray absorptiometry (DXA) scan.

Method: The study was conducted over the period of 12 months from first of January 2012 to end of December 2012. All patients were evaluated clinically for severity of SCD and abnormal bone mass density (BMD) using DXA scan. Blood samples were withdrawn for measuring the serum level of vitamin D3, testosterone, and parathyroid hormone in addition to Hb, LDH, and reticulocyte count. Multiple logistic regression analysis was used to assess risk prediction of different variables for the development of abnormal BMD on DXA with T-score ≤-2.5 standard deviation (SD).

Results: The study included Bahraini patients with SCD (n = 55, age 29.24 ± 9.47 years, male 60% and female 40%) compared with an age-matched healthy control group (n = 55, age 28.82 ± 8.64 years, with 62% male and 38% female). Of the 55 patients with SCD compared with the control group, there were 33 (58%) patients with low BMD and 2 (3%) in the control. Among the 33 patients with SCD and with low BMD, there were 20 (36%) with osteoporosis (T-score of ≤-2.5 SD) and 13 (24%) with osteopenia (T-score of <-1 to -2.5 SD). The most affected site of low BMD was lumbar spine (55%), followed by the radius (30%) and neck of the femur (15%). SCD patients with osteoporosis compared with the healthy subjects had significantly lower body surface area (BSA, m(2)) of 1.4 ± 0.3 vs. 1.63 ± 0.5 BMI, low level of vitamin D3 of 21.11 ± 6.95 ng/mL vs. 46.2 ± 15.19 (P < 0.001), lower testosterone level of 1.34 ± 0.54 vs. 2.18 ± 0.56 ng/mL (P < 0.001), higher reticulocyte count (P < 0.001), and higher LDH level (P < 0.001). The low serum level of vitamin D3 (<20 ng/mL) and low testosterone of <0.9 ng/mL had risk prediction (odds ratio) of 1.14 and 1.2, respectively, for abnormal BMD in SCD. In the risk prediction of other variables of parathormone (PTH), LDH, and reticulocyte, were not significant.

Conclusion: The prevalence of abnormal bone mass density (BMD) is high (60%) in Bahraini patients with SCD. There is significant low serum level of vitamin D3 and low testosterone hormone in those with very low bone mass density (BMD) (osteoporosis and T-score <-2.5). The low serum level of vitamin D3 (<20 ng/mL) and low testosterone of <0.9 ng/mL had risk prediction (odds ratio) of 1.14 and 1.2, respectively, for abnormal BMD in SCD.