A Comparative Study to Assess Parathyroid Hormone Status in Different Age Groups of b-Thalassaemia Major Individuals from Eastern India

Introduction: β-thalassaemia major, due to imbalance, missing or deficiency of β-globin chain synthesis pathway, is marked as a hereditary disorder. Homozygous state presents with severe anaemia. Regular blood transfusions and chelation therapy increase the life expectancy in thalassaemia patients. Due to recent advances in the treatment paradigm of β-thalassaemia major patients, there has been a significant increase in their lifespan but, due to the treatment related iron overload, endocrine defects like hypogonadism, diabetes mellitus, hypothyroidism and Hypoparathyroidism (HPT) have been seen to progress. Diverse studies state the occurrence of HPT to be from none upto almost 22.5% in patients. It has also been recognised that asymptomatic hypocalcaemia is much more common and can be overlooked unless precisely viewed.

Aim: To estimate and compare the biochemical parameters related to bone turnover in regularly transfused thalassaemia patients in different age groups and to find out significant correlation among the biochemical markers.

Materials and Methods: In this cross-sectional study conducted at Calcutta National Medical College, Kolkata, West Bengal, India, from January 2017 till January 2018, 100 β-thalassaemia major patients were enrolled. Serum Parathyroid Hormone (PTH), serum ferritin, ionic calcium (Ca2+), Alkaline Phosphatase (ALP), phosphorus (P) and 25-Hydroxy vitamin D (25-OHD) levels were estimated in these patients. Statistical evaluation was done by the Statistical Package for the Social Sciences (SPSS), version 12.0. Result was reported as mean±SD. Pearson correlation coefficient was used to determine the association of serum ferritin levels and parathormone levels. The p-value of <0.05 was considered as statistically significant.

Results: Out of 100 patients, 19 patients had HPT. The mean age was found to be 12.6 years on diagnosis, mean ionised calcium was 0.95 mmol/L, mean serum ferritin was 3045 μg/L (range 1209-10,000 μg/L) and mean serum phosphate was 1.88 mmol/L (range 1.50-2.73 mmol/L). Serum PTH values of 7.04 pg/mL was found to be low. Negative correlation serum PTH and ferritin levels were found. Significant higher values of mean serum ferritin (2789 μg/L) and lower values of parathormone (17.13 pg/mL) was found in the age group of 11-18 years as compared to the other age group of ≤10 years with serum ferritin and parathormones values being 1648 μg/L and 23.44 pg/mL, respectively.

Conclusion: Regularly transfused β-thalassaemia major patients, inspite of receiving chelation therapy tend to develop altered calcium and vitamin D homeostasis once they enter second decade of life. Thereby, biochemical parameters related to bone profile which includes ionic calcium, vitamin D, phosphate and parathyroid hormones levels should stringently monitored once the patient crosses first decade of life to prevent any development of hypocalcaemia or overt HPT.