Resetting the detection level of cord blood thyroid stimulating hormone (TSH) for the diagnosis of congenital hypothyroidism

An appraisal of a 17-year primary thyroid stimulating hormone (TSH) screening programme for the detection of congenital hypothyroidism was carried out to establish the reference interval of cord blood TSH in unaffected infants; the mean cord blood TSH concentration of affected infants and the incidence of congenital hypothyroidism in the Najran province of Saudi Arabia. Our findings show a reference interval of cord blood TSH of 2.0-16.8 mU/l in unaffected infants; a mean cord blood TSH concentration of 399 mU/l in affected infants; a false positive rate for the diagnosis of at-risk infants of 1.02% and a congenital hypothyroidism incidence rate of 34/100 000 (1 : 2931) live births. These findings suggest that there is a need to reset the cord blood TSH concentration for the detection of at-risk infants. We suggest that the detection level of cord blood TSH for the recognition of at-risk infants can be set at 90 mU/l rather than the recommended level of 30 mU/l. This should reduce the false positive rate for detection of infants at risk of congenital hypothyroidism.