Bone mineral density in ex-thalassemic pediatric patients

The role of using different reference population in the prevalence of low BMD in the thalassemia patients

Purpose

Prevalence of osteoporosis reported as high as 50% in thalassemia major patients. We compared bone density (BMD) of our patients with results of bone densitometry of participants of a national study, to find if BMD diagnosis is ethnicity sensitive or not.

Methods

In 177 adult beta thalassemia major patients and 490 normal subjects of 20-39 y/o range, dual-energy X-ray absorptiometry of the spine and femur performed. Normal subjects participated in Iranian Multi-center Osteoporosis Study (IMOS). Mean and standard deviation of normal ones achieved and Z-score of patients re-calculated based on normal Iranians. As BMD of normal participants and patients performed by devices of different brands, analyses done based on calculated standard BMD of all participants.

Results

BMD of patients was significantly lower than normal participants (P value <0.001). Frequency of Z-score ≤-2 found in 52% and 56% of patients in femur and spine regions, respectively. New Z-score of patients according to Iranian normal populations calculated. Frequency of this new Z-score ≤-2 found in 16% and 72% of patients in femur and spine regions, respectively.

Conclusions

We think in secondary osteoporosis, may be other cut-off points, especially according to BMD of normal population of that geographical region are needed.

Relationship between endocrine changes and bone markers in pediatric thalassemic patients after hematopoietic stem cell transplantation

BACKGROUND

Beta thalassemia major and its treatment by hematopoietic stem cell transplantation can have deleterious effects on bone integrity and a main part of such effects is due to their deleterious effects on endocrine systems. So, we assessed the effects of endocrine changes during HSCT (Hematopoietic Stem Cell Transplantation) on growing bones of pediatric thalassemic patients.

METHODS

Bone-specific alkaline phosphatase and osteocalcin (bone formation markers), N-terminal telopeptide (NTX, bone resorption marker), calcium (Ca), phosphorus (P), alkaline phosphatase (Alk ph), parathyroid hormone (PTH), vitamin D (vit D), prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroxine (T4), triiodothyronine (T3), thyroid-stimulating hormone (TSH), insulin-like growth factor 1 (IGF-1), testosterone (in males) or estradiol (in females), measured in 20 major thalassemic patients with mean age of 10.8±3.9 years. Parameters at the baseline (before HSCT), and 1 month and 3 months after HSCT.

RESULTS

After stem cell transplantation, changes of mean serum levels of NTX, osteocalcin, prolactin, LH, T4, IGF-1, testosterone (in males), Ca, Alk ph, PTH, and vit D were not significant, but bone specific Alk ph, P, T3, TSH, FSH and estradiol changed significantly (P=0.013, P=0.001, P=0.48, P=0.02, P=0.04 and P=0.001, respectively). After one month, there was a significant positive relationship between osteocalcine and T3 (p= 0.009). After 3 months, also, there was a significant positive relationship between osteocalcine and T3 and T4 as well as a negative one with IGF-1 (P<0.001, P<0.02 and P<0.03, respectively).

CONCLUSIONS

Endocrine disorders do not appear to have an overall positive or negative effect on bone metabolism (anabolism or catabolism) in HSCT pediatric thalassemic patients in short term (three months).

Comparison of bone mineral density changes in pediatric thalassemic patients with and without hematopoietic stem cell transplant

OBJECTIVES

Beta thalassemia major is a genetic hemoglobin disorder that affects bone density. The disease leads to deteriorating bone structure but can be treated with hematopoietic stem cell transplant. We aimed to assess bone mineral density changes in pediatric beta thalassemia major patients who had undergone a hematopoietic stem cell transplant compared with similarly affected patients who had not undergone a hematopoietic stem cell transplant.

MATERIALS AND METHODS

Forty beta thalassemia major patients, 20 transplant and 20 nontransplant, younger than 16 years of age were enrolled. The mean age of transplant patients was 8.15 years and nontransplant patients was 9.5 years (P = .242). The female:male ratio was 1:1 in both groups. None of the patients reached puberty during this study. Bone mineral density was evaluated in transplant patients before and 1 year after hematopoietic stem cell transplant. Bone mineral density of nontransplant patients also was evaluated 1 year after their initial bone mineral density test. A Norland XR-46 densitometer was used to make all bone mineral density measurements. None of the patients had a z score < -2.

RESULTS

Mean bone mineral density changes in the femur and spine during this study were 0.008 ± 0.075 g/cm2 and 0.048 ± 0.045 g/cm2 in transplant patients and 0.045 ± 0.072 g/cm2 and 0.036 ± 0.058 g/cm2 in nontransplant patients. No significant differences between bone mineral density changes in transplant and nontransplant patients were detected during the study.

CONCLUSIONS

No significant effects on bone mineral density were detected in hematopoietic stem cell transplant pediatric beta thalassemia major patients compared with similarly affected nontransplant patients. Studies of longer duration may be required to identify significant changes in bone mineral density in hematopoietic stem cell transplant patients.

Relation between BMD and biochemical, transfusion and endocrinological parameters in pediatric thalassemic patients

Low BMDs, short stature, hypogonadism, subclinical hypothyroidism, and IFG are found in 3.3, 10, 33, 16.6, 6.6, and 26.6 % of 30 pediatric β thalassemia major patients, respectively. Age is related with low Z-scores. Short stature and hypogonadism patients were older. These patients' monitoring in late childhood and early teenage for these complications is recommended.

BACKGROUND

Beta-thalassemia major patients frequently have low BMD and increased fracture risk. We tried to determine the relation between BMD and biochemical, transfusion, and endocrinological parameters in pediatric patients.

METHODS

Thirty beta-thalassemia major patients entered the study. Male to female ratio was 14/16. Physicians collected demographic; anthropometric; menstrual; transfusion and treatments histories; and serum levels of calcium, phosphorus, alkalin phosphatase, FBS, Hb, Ferritin, T3, T4, TSH, LH, FSH, testosterone (for boys), and estradiol (for girls). BMD of the spine and femur was measured using a DXA Norland XR-46 device.

RESULTS

Prevalence of "low bone density" (Z-score < -2) in the spine and femur was 3.3 and 10 %, respectively. Short stature (Z-score < -2.5) and hypogonadism was seen in 33 and 16.6 % of patients, respectively. Hypogonadism was found only in boys. Subclinical hypothyroidism and impaired fasting glucose were found in 6.6 and 26.6 % of our patients, respectively. Age and transfusion duration was positively related with spinal BMD (P values, <0.001 and <0.001, respectively), and both related negatively with spinal Z-score (P values, 0.014 and 0.043, respectively). Age and transfusion duration related positively with femoral BMD (P values 0.030 and 0.017, respectively), and both related negatively with femoral Z-score (P values, 0.015 and 0.041, respectively). Mean age of short stature and hypogonadism patients were significantly higher than those who were normal (P values, 0.007 and 0.044, respectively).

CONCLUSION

The main factor related with lower Z-scores of the femur and spine was age. Short stature and hypogonadism patients were significantly older. So, we recommend early monitoring of thalassemia patients (in their late childhood and early teenage) for these complications.