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Letters to the Editor

Indian Pediatrics 2005; 42:843-844

Polytransfused Children with Beta Thalassemia Major have Wider Endocrine Dysfunction


We read with interest the brief report entitled "Assessment of adrenal endocrine function in Asian Thalassemics"(1). A large number of children in India undergo long term transfusions and are therefore at risk of hypothalamo-pituitary dysfunction. The paper makes an important observation of detecting biochemical evidence of adrenal hypofunction in polytransfused patients.

The authors describe a low dose (1 micro-gram) and a standard dose (250 microgram) ACTH stimulation test to assess adrenal function. However neither test discriminates between primary (adrenal gland) and secondary (hypothalamus, pituitary gland) adrenal hypofunction. Given that children with beta thalassaemia are more likely to have pituitary malfunction, serum ACTH estimation should be an additional useful test.

A significant proportion of thalassemics have hypogonadotrophic hypogonadism and therefore remain prepubertal in sexual maturation. Delayed puberty itself may partly account for the reduction in weight for age. Of course, other variables such as nutrition, socio-economic status, parental build and ethnic background may also be responsible for small body size. Puberty is an important process not only for sexual maturation but also for bone mineralisation. Puberty should therefore be assessed in all children and the gonadotrophin releasing hormone test performed in those with poor progression.

Iron overload from polytransfusions is well known to cause pituitary failure. The authors measured serum ferritin as an index of iron overload but found no significant correlation with basal cortisol concentrations. It may be noted that thalassaemics who are growth hormone deficient from pituitary iron deposition, have relatively low ferritin levels(2) and this may account for the lack of association.

We should be alert to the real possiblity of growth hormone deficiency, hypogonadot-rophic hypogonadism, hypothyroidism and hypoparathyroidism in all beta thalassaemia children undergoing regular transfusions. In addition to basal cortisol and ACTH, it is important to assess thyroid function, parathyroid hormone and insulin like growth factor-1(IGF-1) in these children. Dual energy X-ray absorptiometry (DXA) scans may be performed where there are adequate resources to assess bone mineral density. Children in growth failure should have a low threshold for undergoing pituitary function tests. Those complaining of tiredness or fatiguability should be investigated with the low dose ACTH test for adrenal reserve. A pituitary magnetic resonance scan may be considered as an investigation to visualize pituitary iron overload(3).

I. Banerjee,
Department of Pediatric Endocrinology,
Royal Manchester Children’s Hospital,
United Kingdom.
E-mail: ibanerjee@freeuk.com

References

1. Srivatsa A, Marwaha RK, Muralidharan R, Trehan A. Assessment of adrenal endocrine function in Asian Thalassemics. Indian Pediatrics 2004; 42: 31-35.

2. Masala A, Atzeni MM, Alagna S, Gallisai D, Burrai C, Mela MG, et al. Growth hormone secretions in polytransfused prepubertal patients with homozygous beta thalassemia. Effect of long term recombinant growth hormone (rec GH) therapy. J Endocrinol Invest 2003; 26: 623-628.

3. Argyropoulou MI, Metafratzi Z, Kiortsis DN, Bitsis S, Tsatsoulis A, Efremidis S. T2 relaxation rate as an index of pituitary iron overload in patients with beta-thalassemia major. AJR Am J Roentgenol. 2000; 175: 1567-1569.

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