Prevalence of poor neuro-developmental outcome and hypothyroidism among 5-9 year-old children in the plantation sector of Sri Lanka

Abstract

INTRODUCTION AND OBJECTIVES: To describe the prevalence of poor neuro-developmental outcome and its relationship to hypothyroidism among 5-9 year-old children in the plantation sector of Sri Lanka. METHODS: This descriptive cross-sectional study was conducted in 20 randomly selected estates in the Ratnapura district. Using a validated tool based on Griffiths mental development scale, neruo-developmental outcome of 1683 children aged 5-9 years was assessed. The results were expressed using the General Quotient (GQ) score [GQ score<100 = poor neruo-developmental outcome]. A 2ml blood sample was obtained from a sub-sample of 519 children after obtaining informed written consent from the parents/guardians and TSH level was assayed. Presence of clinical symptoms of hypothyroidism and visible/palpable goitre were assessed among those who had a TSH>5.4 u-IU/ml (biochemical hypothyroidism). RESULTS: GQ<100 was identified in 9.4% of children and a high TSH (>5.4uTU/ml) was detected in 3.7% of children. Low TSH (<0.6uiU/ml) was detected in 1.2%. The prevalence of poor neuro-developmental outcome with high TSH was 2.1%. There was no association between TSH levels and age and sex. TSH level was significantly associated with neuro-developmental outcome (p<0.001). 15.8% of children with biochemical hypothyroidism had clinical symptoms of hypothyroidism and goitre was visible or palpable in 15.7%. Poor neuro-developmental outcome was present in 58% of these children. CONCLUSIONS: Poor neuro-developmental outcome was evident in a large proportion of children with biochemical hypothyroidism without clinical features of hypothyroidism. These findings indicate a link between poor neuro-development and sub clinical hypothyroidism which has not been described before.