Reduced bone mineral density in childhood chronic idiopathic thrombocytopenic purpura treated with high-dose methylprednisolone

Bone Mineral Density Assessment by Quantitative Computed Tomography in Glucocorticoid-Treated Boys With Duchenne Muscular Dystrophy: A Linear Mixed-Effects Modeling Approach

OBJECTIVE

Boys with Duchenne muscular dystrophy (DMD) are at risk of bone damage and low bone mineral density (BMD). The aim of the study is to examine lumbar BMD values measured by QCT and identify the factors associated with BMD loss using a multilevel mixed-effects model.

METHODS

Lumbar BMD was evaluated by quantitative computed tomography (QCT) at diagnosis, 1 and 2 years follow up in patients with DMD who were treated with GC. Demographic data, functional activity scores (FMSs), laboratory parameters and steroid use were recorded. A multilevel mixed-effects model was used to analyze BMD loss.

RESULTS

Nineteen patients with DMD who had a total of sixty complete records between January 2018 and October 2021 were retrospectively analyzed. At baseline, 15.8% of patients (3/19) had low lumbar BMD (Z score ≤ -2), and the mean BMD Z score on QCT was -0.85 (SD 1.32). The mean BMD Z score at 1 and 2 years postbaseline decreased to -1.56 (SD 1.62) and -2.02 (SD 1.36), respectively. In our model, BMD Z score loss was associated with age (β=-0.358, p=0.0003) and FMS (β=-0.454, p=0.031). Cumulative GC exposure and serum levels of calcium, phosphorus, 25(OH)-vitamin D and creatinine kinase did not independently predict BMD loss.

CONCLUSIONS

This study demonstrates that in DMD patients, lumbar BMD decreased gradually and progressively. Age and FMS are the main contributors to BMD loss in boys with DMD. Early recognition of risk factors associated with BMD loss may facilitate the development of strategies to optimize bone health.

Bone mass and biochemical markers of bone turnover in children and adolescents with chronic immune thrombocytopenia: relation to corticosteroid therapy and vitamin D receptor gene polymorphisms

Optional drug therapy in refractory chronic immune thrombocytopenia (ITP) includes standard oral, pulsed high-dose steroid therapy, intravenous gamma globulin, anti-D, and immunosuppressive therapy or thrombopoietin receptor agonists. This work aimed to study the bone mass in children and adolescents with chronic ITP in relation to biochemical markers of bone turnover, cumulative steroid therapy, and the possible modulating effect of vitamin D receptor (VDR) gene polymorphisms. Thirty-six children and adolescents with chronic ITP were recruited from the Hematology Clinic, Children's Hospital, Ain Shams University and the Hematology Clinic of the National Research Centre in Egypt and compared with 43 healthy age- and sex-matched controls. The total cumulative dose of steroids was calculated. Bone markers (serum osteocalcin (OC) and propeptide I precollagen (PICP) and urinary deoxypyridinoline (DPD) excretion), analysis of VDR gene distribution, and dual energy X-ray absorptiometry at lumbar and hip regions were performed for patients and controls. Compared to controls, chronic ITP patients had higher body mass index (BMI) and lower height for age standard deviation score (SDS). Chronic ITP patients had lower levels of OC and C-terminal propeptide of type I procollagen (PICP) and higher urinary DPD excretion, and bone mineral density (BMD) was significantly lower for both spine and hip z-score (<0.001). BMD was inversely correlated with urinary DPD excretion, age, BMI, and cumulative steroid dose. There was significant negative correlation between cumulative oral steroid dose and BMD (r = -0.4, P = 0.01 and r = -0.45, p = 0.001 for spine and hip z-scores, respectively), but the correlation was non-significant in relation to cumulative pulsed steroid therapy. FokI polymorphism was significantly related to BMD for both spine and hip z-score (p = 0.015 and p = 0.008, respectively), but there was no relation between BMD and Bsm1 polymorphism. FokI gene polymorphism may be one of the contributing factors in bone loss in patients on chronic steroid therapy. High cumulative doses of corticosteroids increased bone resorption in young chronic ITP patients. Longitudinal studies are needed to confirm the effect of different steroid protocols on bone turnover. Protocols of therapy of chronic ITP should restrict corticosteroid use in growing children and favor alternative less harmful therapies.

Late side effects of high-dose steroid therapy on skeletal system in children with idiopathic thrombocytopenic purpura

Corticosteroids have been widely used in the treatment of idiopathic thrombocytopenic purpura (ITP). We evaluated the late side effects of high-dose methylprednisolone (HDMP) therapy on bone metabolism in children with ITP. Twenty-eight children with acute ITP treated with HDMP (30 mg/kg/d for 3 d then 20 mg/kg/d for 4 d) and 28 controls were enrolled in the study. Bone mineral density (BMD), urinary calcium creatinine ratio, urinary levels of deoxypyridinoline, serum levels of calcium, phosphate, parathyroid hormone, total alkaline phosphatase, and bone-specific alkaline phosphatase were measured in both groups. Magnetic resonance imaging of the femoral head was performed only in study group. The mean levels of serum phosphate, parathyroid hormone, urinary deoxypyridinoline, and calcium creatinine ratio were significantly increased in the study group. There was no significant difference between the 2 groups in terms of serum calcium, total alkaline phosphatase, bone-specific alkaline phosphatase, and BMD values. There was a statistically significant negative correlation between cumulative steroid dose and BMD values in study group (r = -0.379). Osteonecrosis was observed in 3 of 25 patients by magnetic resonance imaging. In conclusion, HDMP therapy, especially in high cumulative doses, increases the bone resorption and may cause osteonecrosis in children with ITP.

Low bone mineral density and decreased bone turnover in Duchenne muscular dystrophy

This cross-sectional study examined bone mineral density, bone turnover, body composition and calciotropic hormones in 24 boys with Duchenne muscular dystrophy (DMD) (2.3-19.7 years), most of whom were being treated with prednisolone, and 24 age-matched healthy boys. Our study demonstrated lower bone mineral density in the DMD group for total body, spine, hip, heel and forearm measurements. These differences between DMD patients and controls increased with increasing age. Biochemical markers of both bone formation and resorption revealed reduced bone turnover in DMD patients. The fracture rate was not higher in DMD patients. The DMD group had low vitamin D levels but high leptin levels in comparison with the control group. Muscle strength correlated with bone mineral density assessed at the hip and heel in the DMD group. Interventions that increase bone formation should be considered, as DMD patients have reduced bone turnover in addition to their low bone mineral density.