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Late Effects




Thyroid Screening

Anyone who has had radiation therapy (RT) to their neck directly or to an area immediately adjacent to the neck, where scattered radiation might affect the thyroid should have screening for thyroid problems.

Screening to detect hypothyroidism is important,  This condition causes chronic fatigue and weight gain. 

Low T4 and T3 levels cause elevated TSH levels and this in turn results in an increased risk of multinodular goiter and thyroid cancer.



History and physical

  • Does the patient feel chronically tired and lacking in energy?
  • Has there been any weight gain over the past few months?
  • On examination is there any palpable thyroid abnormality?

Most likely, the patient will not feel any different from normal even if they have hypothyroidism and will not have a palpable thyroid abnormality.


  • Measurement of thyroid function:
    • Serum T3, T4 and TSH
    • May be within normal limits with mild thyroid dysfunction
  • Subtle central hypothyroidism is particularly likely when the T4 value is in the lowest one-third range of normal, and has been reported in about 5% of long term survivors after treatment for childhood cancer.
  • Nocturnal TSH surge and TSH response to TRH
    • Identify subtle problems
    • More sensitive indicator of central hypothyroidism
    • Abnormalities include a blunted TSH surge, low/delayed TSH peak, or delayed TSH decline after TRH


Screening for thyroid nodules and cancer:

In our clinic we aim to:

  • Check routine thyroid function tests (serum TSH, T4 and T3) at least every year
  • Examine the thyroid every year for nodularity.
  • Organize a thyroid ultrasound scan every 3 years
    • Shows thyroid parenchyma in more detail
    • Suspicious nodules can either be followed closely to look for growth or ultrasound guided fine needle aspiration (FNA) biopsy can be organized.


COG survivorship Guidelines for Thyroid Problems






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