Chemistry
Thyroid related
Screening-neonatal hypothyroidism

Author: Nat Pernick, M.D. (see Authors page)

Revised: 23 February 2016, last major update March 2011

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Screening [title] neonatal hypothyroidism
Definition / General
Clinical Features
Diagrams / Tables

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When to screen

Laboratory
Indications
  • Routinely performed on all newborns
  • Screening prevents severe mental retardation if treatment begins within 1 month of birth
  • Mild hypothyroidism may cause cardiovascular mortality or damage to offspring of pregnant women

Methodology
  • Use dry blood spots or cord serum to measure both T4 and TSH
  • If measure only T4 (checking for low values), have high false positive rate due to prematurity or congenital absence of thyroid binding globulin, and miss patients with elevated TSH but normal T4
  • If measure only TSH (checking for values of 10 mIU/L or higher), have false positives from premature or severely stressed infants and miss infants with hypothalamic or pituitary disease

Algorithm
  • Very low birth weight infants (J Med Screen 2005;12:166) and dizygotic twins (An Pediatr (Barc) 2006;65:129) should be retested at 2 weeks and 4 - 6 weeks to detect late onset hypothyroidism
  • TSH less than 10 mIU/L: no further action for newborns
  • TSH 10 - 20 mIU/L: retest at 2 - 6 weeks
  • TSH > 20 mIU/L: endocrine workup needed
Treatment