Introduction: Thalassemia is a disorder of haemoglobin synthesis due to mutations in the globin chains (α or β). Transfusion-dependent thalassaemia is associated with reduced bone mineral density (BMD) and fractures. Many causes are implicated including hypogonadism, growth hormone deficiency, marrow expansion and iron overload. However, the relationship of nephrolithiasis to BMD and fractures has not previously been studied.
Method: A retrospective cohort study of 166 patients with transfusion-dependent thalassaemia was undertaken to determine the prevalence of nephrolithiasis, and its association with BMD and fractures. Logistic regression analysis using age and gender matches was employed to account for potential confounding factors.
Results: There were 73 (44%) male and 93 (56%) female participants aged between 4 to 66 years with a median age of 34 years. Fractures occurred in 19.9% of study participants and were more common in males than females (27.4% vs 14%). The overall prevalence of nephrolithiasis was 18.1%, occurring in 28.7% of males and 9.7% of females. Reduced femoral neck Z scores were associated with an increased risk of nephrolithiasis (OR=1.63; 95% CI: 1.10-2.42). Furthermore, subgroup analysis showed nephrolithiasis in males was associated with an increased risk of fracture after adjusting for femoral neck or lumbar spine Z score (OR=5.59; 95% CI:1.16-27.03, OR=5.21; 95% CI:1.06-25.64, respectively).
Conclusion: Nephrolithiasis is common and significantly associated with reduced BMD and fractures after adjusting for potential confounders. These findings demonstrate the need for ongoing surveillance of BMD, fractures and nephrolithiasis in the management of transfusion-dependent thalassaemia.