What this test measures
Neonatal TSH measures Thyroid Stimulating Hormone in a newborn baby — most often on a heel-prick dried-blood-spot collected 48–72 hours after birth, or on cord blood at delivery in some Indian centres. After birth, normal TSH surges in the first few hours (peaks at 30–60 minutes, sometimes > 50 mIU/L) and then falls rapidly over 3–5 days.
A raised TSH on the screening sample is followed up with confirmatory venous TSH and free T4 to diagnose congenital hypothyroidism — present in roughly 1 in 1500–2500 Indian newborns, somewhat more common than in Western populations.
Why it matters
Congenital hypothyroidism (CH) is one of the most preventable causes of permanent intellectual disability in children. Untreated, severe CH causes profound mental and motor delay, short stature, and characteristic features ("cretinism"). Treated within the first 2 weeks of life with levothyroxine, almost all affected children grow up with normal intelligence and development.
India has not yet rolled out universal newborn TSH screening nationally — coverage is patchy, with private hospitals and tertiary centres being the main providers. The American Thyroid Association, Indian Academy of Pediatrics and the Indian Society for Pediatric Endocrinology all strongly recommend screening every newborn, ideally before discharge.
How to prepare
No preparation needed by the parents. The sample is collected by the hospital — either as a heel-prick dried-blood-spot 48–72 hours after birth, or as cord blood at delivery. For sick or premature babies, a venous sample is sometimes used. Inform the lab if the mother has known autoimmune thyroid disease, has been on antithyroid drugs in pregnancy, or had iodine-contrast imaging — these affect interpretation.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Neonatal TSH (mIU/L)[1][2] | Cord blood: < 20 · Day 3 dried-blood-spot: < 10 · Day 7: < 5 (assay-dependent screening cut-offs) | Low neonatal TSH is rarely a problem on screening. It can occur in central (pituitary or hypothalamic) congenital hypothyroidism — which screening with TSH alone misses, so combining with T4 is preferred. Maternal antithyroid drugs can also suppress neonatal TSH temporarily. | Raised neonatal TSH on screening prompts immediate recall for venous confirmation. A persistently raised TSH (> 20–40 mIU/L depending on assay) with low free T4 = congenital hypothyroidism — start levothyroxine immediately, ideally within 2 weeks of birth. Transient hypothyroidism (from maternal antithyroid drugs, iodine excess, or prematurity) is also possible — re-evaluate after 6 months. |
Neonatal TSH — screening cut-offs
| Sample type | Cut-off | Action |
|---|---|---|
| Cord blood | > 20 mIU/L | Recall for venous TSH + FT4 |
| Day 3 DBS | > 10 mIU/L | Recall for venous TSH + FT4 |
| Day 7 DBS | > 5–6 mIU/L | Recall for venous TSH + FT4 |
| Confirmatory venous (any day) | > 20 + low FT4 | Start levothyroxine immediately |
| Premature / sick / low birth weight | Repeat at 2 weeks | TSH may normalise; some need treatment |
Frequently asked questions
Is newborn TSH screening compulsory in India?
It is recommended by the Indian Academy of Pediatrics and the Indian Society for Pediatric Endocrinology, and is part of newborn screening in many private hospitals and some state government programmes — but there is no universal national mandate yet. Parents should ask the hospital before discharge.
When is the best time to take the sample?
Cord blood (at delivery) or a heel-prick dried-blood-spot at 48–72 hours of age. Sampling too early (< 24 hours) catches the post-birth TSH surge and gives many false positives. Sampling too late risks delayed diagnosis.
My baby's screening TSH is high — does that mean she has hypothyroidism?
Not necessarily — a positive screen requires confirmation with a venous TSH and free T4. About 1 in 30 positive screens turn out to be true congenital hypothyroidism; the rest are mild transient elevations.
How urgent is starting treatment if it is confirmed?
Very urgent. Treatment should ideally start within the first 2 weeks of life. Babies treated early have essentially normal IQ and development; delayed treatment risks permanent intellectual disability.
Is the treatment lifelong?
For most children with permanent congenital hypothyroidism, yes — daily levothyroxine for life. A few children with transient causes (maternal antithyroid drugs, iodine excess) can stop treatment after 2–3 years following a careful re-evaluation.
Can my baby have hypothyroidism without us noticing?
Yes — that is exactly why screening exists. Symptoms (prolonged jaundice, poor feeding, lethargy, constipation, large tongue, umbilical hernia, hoarse cry) are often subtle in the first weeks. By the time obvious features appear, irreversible brain damage may have started.
Does prematurity affect the result?
Yes. Premature babies have lower TSH surges and immature thyroid axes. Many neonatal units repeat the test at 2 weeks and at term-equivalent age. Some transient hypothyroidism of prematurity needs short-term treatment.
Related Hormones / Endocrine tests
Tests commonly ordered alongside NEONATAL THYROID STIMULATING HORMONE # (TSH), or that help interpret an unexpected result.
Sources & references
- American Thyroid Association — Congenital Hypothyroidism Guideline · accessed 2026-05-30T00:00:00.000Z
- Indian Academy of Pediatrics — Newborn Screening Guidance · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Newborn Screening · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Congenital Hypothyroidism · accessed 2026-05-30T00:00:00.000Z
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