Background: Down syndrome is associated with various forms of thyroid dysfunction, hypothyroidism being the most common. The additive effects of both co-morbid conditions lead to further amplification of the clinical problems in these children with Down syndrome.

Objective: The purpose of this prospective study was to know the prevalence of thyroid dysfunction in Down Syndrome children below the age of 14 years and to correlate the features of Down Syndrome with those of thyroid dysfunction.

Methods: In all 32 Down syndrome children were grouped as euthyroid, compensated and uncompensated

hypothyroidism on the basis of their T3, T4 and TSH levels and the features of were compared using the student’s t-test.

Results: Hypothyroidism was seen in 5 out of 32 cases (15.6%) of which 1 (3.1%) had uncompensated while the other 4 (12.5%) had a compensated hypothyroidism. Hyperthyroidism was not observed in any of the cases. The prevalence of hypothyroidism of 16.7% on the age group 0 –1 year could well be a reflection of congenital hypothyroidism while 20% prevalence in the age group 9 – 12 could imply acquired hypothyroidism. The mean values of the developmental quotient (D.Q.) and the Rao’s index in Down syndrome cases with hypothyroidism was 49 ±5.1 and 0.15 ± 0.06 respectively while that of euthyroid Down syndrome patients were 52 ± 5.54 and 0.17 ± 0.04 respectively (‘p’ value > 0.05), the differences though obvious yet not statistically significant.

Conclusion: It thus seems necessary to screen all Down syndrome children for thyroid dysfunction