Congenital Hypothyroidism

Thyroid

Report in 72Hrs

At Home

No Fasting Required

Details

Newborn thyroid screen.

₹296₹423

30% OFF

Congenital Hypothyroidism Test Information Guide

Why is it done?
- Detects abnormally low thyroid hormone levels in newborns to prevent intellectual disability and developmental delays
- Identifies thyroid dysgenesis (absence or underdevelopment of thyroid gland), dyshormonogenesis (enzyme defects affecting hormone production), and central hypothyroidism
- Part of mandatory newborn screening programs in most developed countries, performed between 24-48 hours after birth
- Early detection allows timely thyroid hormone replacement therapy to prevent permanent neurological damage and support normal growth and development
- Screening typically uses dried blood spots collected from heel prick onto filter paper cards
Normal Range
- TSH (Thyroid Stimulating Hormone) - Primary marker: Normal range typically 5-25 mIU/L or 0.5-5.0 mIU/L (varies by laboratory)
- Free T4 (Thyroxine) - Secondary marker: Normal range typically 10-20 ng/dL or 1.2-2.4 ng/dL (varies by laboratory)
- Negative/Normal Result: TSH and T4 levels within age-appropriate reference ranges, indicating normal thyroid function
- Positive/Abnormal Result: Elevated TSH with low or low-normal T4 (primary hypothyroidism), or low TSH with low T4 (central hypothyroidism)
- Borderline Results: May warrant repeat testing, as some newborns may have transient TSH elevations or delayed thyroid maturation
- Units of Measurement: TSH in mIU/L (milli-international units per liter), T4 in ng/dL or pmol/L (nanograms/picomoles per deciliter/liter)
Interpretation
- Elevated TSH with Low T4 (Primary Hypothyroidism): Indicates thyroid gland dysfunction; most common form affecting approximately 1 in 3,000-4,000 newborns. Most frequent cause is thyroid dysgenesis (85-90% of cases)
- Low TSH with Low T4 (Central Hypothyroidism): Indicates pituitary or hypothalamic dysfunction; less common, affects approximately 1 in 16,000-25,000 newborns. Requires additional imaging and hormone testing
- Elevated TSH with Normal T4 (Mild TSH Elevation): May represent early thyroid disease, transient hypothyroidism, or false positive result. Requires confirmatory testing and follow-up evaluation
- Thyroid Dysgenesis: Includes aplasia (absent thyroid), hypoplasia (underdeveloped thyroid), or ectopia (thyroid in abnormal location). Confirmed by thyroid imaging (ultrasound or scintigraphy)
- Dyshormonogenesis: Enzyme defects preventing normal thyroid hormone synthesis; accounts for 10-15% of cases. Usually shows elevated TSH with absent or very low T4
- Factors Affecting Results: Timing of sample collection (TSH rises after birth), prematurity, maternal iodine status, maternal antithyroid medications, iodine contamination in collection process, hemolyzed or insufficient samples
- Clinical Significance: Early diagnosis and treatment with levothyroxine replacement can completely prevent intellectual disability and ensure normal neurodevelopment. Untreated congenital hypothyroidism leads to cretinism with severe intellectual disability, growth retardation, and developmental delays
Associated Organs
- Primary Organ System: Thyroid gland, pituitary gland (anterior), hypothalamus, and the endocrine system. The nervous system is also critically affected by thyroid hormone deficiency
- Associated Medical Conditions: Down syndrome (increased incidence of congenital hypothyroidism), Turner syndrome, Pendred syndrome, iodine deficiency disorders, maternal Graves' disease with transplacental transfer of blocking antibodies
- Diseases Diagnosed or Monitored: Congenital primary hypothyroidism (thyroid dysgenesis, dyshormonogenesis), central hypothyroidism (pituitary/hypothalamic insufficiency), transient hypothyroidism, primary hypothyroidism with thyroid peroxidase (TPO) antibodies
- Complications if Left Untreated: Severe intellectual disability and developmental delays (cretinism), growth retardation, delayed bone maturation, impaired cognitive development, poor feeding, constipation, jaundice, hypothermia, weak cry, lethargy, developmental regression if treatment delayed beyond first weeks of life
- Systemic Effects of Thyroid Hormone Deficiency: Decreased metabolic rate affecting all body systems, neurological development impairment, cardiac effects (bradycardia, decreased contractility), thermal regulation problems, gastrointestinal dysfunction
Follow-up Tests
- Confirmatory Testing: Serum TSH and free T4 from venipuncture (not dried blood spot) within 24-48 hours of abnormal screening result to confirm diagnosis before initiating treatment
- Thyroid Imaging Studies: Thyroid ultrasound to assess thyroid anatomy and detect dysgenesis, or thyroid scintigraphy (technetium-99m or iodine-123) to evaluate thyroid function and uptake capacity. Recommended within first 2 weeks of life for confirmed cases
- Thyroid Peroxidase (TPO) Antibodies: May be tested if autoimmune thyroiditis is suspected, particularly if family history of autoimmune thyroid disease present
- TSH Receptor Antibodies (TRAb): May be tested if maternal history of Graves' disease exists to determine if transient neonatal hypothyroidism is present
- Genetic Testing: May be performed for suspected dyshormonogenesis or genetic forms of central hypothyroidism; genes tested include TPO, TGAL, TSHR, PAX8, and others involved in thyroid development
- Pituitary Imaging (MRI): Recommended for central hypothyroidism to evaluate pituitary and hypothalamic structures, assess for pituitary hypoplasia, or identify other anatomical abnormalities
- Other Pituitary Hormone Testing: Prolactin, growth hormone, ACTH, and cortisol assessment if central hypothyroidism confirmed, as multiple pituitary hormone deficiencies may be present
- Monitoring During Treatment: TSH and free T4 rechecked at 2 weeks, 4 weeks, 3 months, 6 months, 1 year of age, then annually or as clinically indicated to ensure adequate levothyroxine dosing and maintain optimal thyroid hormone levels
- Reassessment at Age 3-4 Years: Off-therapy trial (trial discontinuation) may be considered for transient hypothyroidism cases to confirm if treatment can be discontinued, with repeat testing 2-4 weeks after stopping therapy
Fasting Required?
- Fasting Requirement: No
- Sample Collection Method: Newborn screening uses dried blood spot from heel prick onto filter paper card - fasting not applicable or necessary for newborns
- Confirmatory Serum Testing: Fasting not required; can be performed at any time. Standard venipuncture collection procedure used for serum TSH and T4 testing
- Special Instructions for Newborn Screening: Sample collection should occur between 24-48 hours after birth for optimal TSH elevation detection. Samples collected too early (<24 hours) may have false negative results due to insufficient TSH rise
- Medications: No specific medications need to be avoided for screening test. However, maternal medications (iodine-containing compounds, antithyroid drugs) may affect results and should be documented
- Other Preparation Requirements: Heel should be warmed gently before prick to promote blood flow. Newborn should not be squeezed excessively. Filter paper card must be filled completely and allowed to air dry thoroughly. Avoid contamination with antiseptics containing iodine
- Transport and Storage: Dried blood spot cards must be stored at room temperature and transported promptly to laboratory. Samples should not be refrigerated or exposed to extreme heat or humidity

How our test process works!