Question of the Week

Question :

Posted On : 24 Jul 2006

I need clarification regarding congenital hypothyroidism screening. Some countries do screening for TSH from cord blood while some screen by T4 levels from neonates at Day 5 of life. Why the difference in preferance? Which is more sensitive for detection of primary hypothyroidism?

Expert Answer :

No expert answer available.

Answer Discussion :

Dr Sushil Madan

Maternal TRH can cross the placenta but not the tsh ,while fetal thyroid gland andhypothalimic-pituitary-thyroid axis functionlargely independently of that of the mother.Hence TSH REMAINS THE MOST SENSITIVEINDEXof primary hypothyroidism at birth.After 5 days free T3 ESTIMATION CAN BE DONEwhich is 4 times more potent than T4.

18 years ago

dr sanjeev aggarwal

The ideal time of doing screening for cong.hypothyroidism is after 3-4 days of birth{because there is physiological rise in level of TSH after birth in response to hypothermia experienced by the baby which settles down in next 3-4 days}.However ,the practical problem is that the babies are discharged from the hosp' by that time,therefore making it difficult to screen on day 4{heel prick sample is taken}.Therfore many screening programmes do screen with cord blood only,{whereby the risk of false positivity is higher},and repeat TSH for reconfirmation on day 4 or later if found high.

18 years ago

Dr. M Natarajan

cordblood

18 years ago

kantakumari

18 years ago

kantakumari

t4 is more specific,

18 years ago

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