Distribution of T4 TSH values in children--the Shifa experience.

Objective:To evaluate the distribution of Thyroxin (T4) and Thyroid Stimulating Hormone (TSH) values in children of various age groups attending our hospital. Method:We have retrospectively reviewed the T4, TSH levels recorded at our hospital in children from birth to 5 years and evaluated the reference intervals for T4 TSH amongst different ages. Non parametric methods were used to establish a 97.5th, 95th, 50th, 5th and 2.5th centiles. Results: In T4 (n=1148) and TSH (n=1142) samples reviewed a TSH surge following delivery showed a sharp decline in the first 4 days of life. This was followed by a more gradual downward trend. Data on T4 estimations showed a similar but more gradual downward trend in advancing age groups. The 5th 95th centile reference range for TSH showed values between 1.7--22.5 (O--4days; n=992), 0.6--13.3 (5--7days; n=36), O.9-14.O (lweek--1 month; n=38), 0.5--i 3.6 (1 month-I year; n=38) and 0.4--12.8 (1—5 years; n38) microlU/mL. The 5th 95th centile reference range for T4 showed values between 10.7-25.0 (0-4days; n=995), 6.5--20.4 (5-7 days; n=35), 8.0-18.1 (iweek--imonth; n=38), 6.0—16.1 (Imonth--iyear; n=4i), 6.9-i 5.3 (i--S years; n=39) micro gm/dI. Conclusion:We recommend using separate T4 and TSH reference values for children in different age groups. Further large-scale studies should be done in Pakistan to establish these reference values within age groups. A national center for neonatal thyroid screening is highly recommended JPMA 53:26;2003).