Article Text

INDICATIONS AND TIMING OF THYROID FUNCTION TESTS IN NEWBORNS
  1. P Gallagher1,
  2. N Murphy2,
  3. A Foran1
  1. 1Department of Paediatrics, Rotunda Hospital, Dublin, Ireland
  2. 2Department of Endocrinology, Children’s University Hospital, Dublin, Ireland

Abstract

Background Thyroid disorders affect approximately 1 per 3000 term infants. The majority are congenital hypothyroidism picked up by newborn screening (Guthrie). International guidelines advise checking TFTs in infants born to mothers if there is an autoimmune basis to the maternal thyroid disease or unknown cause. Testing should be deferred until 72 hours after delivery.

Aims

  • Audit TFTs performed on neonates in the Rotunda.

  • Assess if the test was: indicated, done at the right time and an adequate sample.

Aims

Methods

  • Retrospective review Jul–Dec 2007.

  • Internal laboratory computer system.

  • Chart review.

Methods

Results

  • 57 infants had TFTs Jul–Dec ’07.

  • 15/89 samples (17%) were insufficient.

  • 5 with abnormal results: 4 detected by Guthrie and 1 presented with hypoglycaemia.

  • 17 infants had TFTs as a result of maternal thyroid disease. Of these: 11/17 were taken for the wrong reason or at the wrong time. 4 too late (>day 14) and 4 too early. 3/17 had TFTs performed unnecessarily as the mothers had previous surgery for benign thyroid lesions. None of these samples yielded positive results.

Results

Conclusion

  • The Guthrie remains the gold standard screen for identifying infants with thyroid disease.

  • This audit highlights the need for a guideline indicating appropriate indications and timing of TFTs for infants born to mothers with thyroid disease.

  • In high-risk mothers with known antibodies or no known cause for their thyroid disease then samples must be correctly timed, to avoid repeated phlebotomy and missing potentially life-threatening thyrotoxicosis.

Conclusion

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