TSH assay using dried blood samples: a screening method for congenital hypothyroidism

Capillary blood samples from three hundred healthy, full-term newborn within 48 and 120 hours of delivery, were collected on filter paper for analysis of thyroid-stimulating hormone (TSH). Blood was collected by pricking the heel of the newborn and spotted and dried on filter paper cards. The samples were analysed by immunoradiometric assay (IRMA) to determine the TSH level. Some fifteen percent of a total 1928 deliveries at two hospitals during a period of one year were included in the study. Male:female ratio was 1.1:1. There was no maternal history of thyroid disease. None of the babies had any clinical feature of hypothyroidism. On analysis, TSH level ranged from 0.6-19.3 microU/ml with a mean (SD) of 7.19 (4.21) microU/ml. TSH assay from dried filter paper blood spot is technically possible and is a cost-effective and reliable method for a screening programme. This is the first time in Bangladesh that this method has been successfully carried out.