Impact of maternal thyroid disease on neonatal thyroid status.

OBJECTIVES: Prevalence of Maternal and congenital hypothyroidism is on the rise. To present the thyroid stimulating hormone screening results in babies born to hypothyroid mothers and assess the burden, aetiology of hypothyroidism in these babies. METHODS: All antenatal mothers attending our hospital during the study period were enrolled into the study. Group I includes 249 term babies born to hypothyroid mothers and group II comprises 2154 newborns born to mothers who are euthyroid. Heel prick thyroid stimulating hormone was done for all newborns on day 3 for both groups. Confirmatory venous testing was done for all for babies in group I and screen positives belonging to group II. Evaluation and therapy done as per standard guidelines. RESULTS: Thyroid stimulating hormone values in the two groups are presented. There was significant correlation between peak maternal thyroid stimulating hormone and neonatal day 3 heel prick in group I (r=0.7, P<0.05). The prevalence of positive screening test in groups I and II was 3.8 and 1.03% (p<0.05) whereas corresponding values for confirmed disease was 4.3 and 0.6%, respectively (p<0.05). Aetiological evaluation revealed both transient hypothyroidism (33.3%) and permanent hypothyroidism (66.6%). CONCLUSION: 4.3% of babies born to hypothyroid mothers develop congenital hypothyroidism; aetiology being both transient and permanent. A venous test by 3 weeks is helpful in these babies to improve case identification.

Utility of the New Indian Society of Paediatric and Adolescent Endocrinology (ISPAE) Guidelines for Congenital Hypothyroidism Screening in a High Risk Unit.

OBJECTIVE: To study the new ISPAE guidelines in neonates with congenital hypothyroidism and present authors' experience in managing these neonates. METHODS: A retrospective review of all babies who were screened for congenital hypothyroidism in the institution over a period of 5 y was conducted. Details pertaining to maternal risk factors, neonatal risk factors, screening TSH, venous TSH and details of etiological evaluation including: ultrasound thyroid, technetium 99m scintigraphy and anti thyroid peroxidase antibody estimation were retrieved. The cases were assessed using the new ISPAE guidelines. RESULTS: During the study period, 8107 babies were screened for congenital hypothyroidism, 83 cases had confirmed disease and 47 had established etiology. There is a fair correlation between screening TSH and venous TSH (r = 0.7, p < 0.05). The estimated incidence of congenital hypothyroidism in present series is 1 in 97 cases. Out of the 83 cases, 36 (43.3%), 16 (19.2%) and 31 (37.3%) cases had screening TSH >20 µIU/mL, 6-20 µIU/mL and < 6 µIU/mL, respectively. Out of the 47 babies with screening TSH <20 µIU/mL, 23 (48.9%), 25 (53.1%) and 12 (25.5%) cases had prematurity, maternal thyroid disease and illness, respectively, as risk factors (some babies had more than one risk factor). Of the 83 cases, all of them had venous TSH >10 µIU/mL and five cases had low Free T4 (<1.1 ng/dl). Thus, none of the cases with congenital hypothyroidism were missed on the new ISPAE guidelines. CONCLUSION: The new ISPAE guidelines for neonatal screening for congenital hypothyroidism are very useful and applicable in Indian neonates.