Thyroid Function

Low / Normal TSH with Low T4



  • A reduced or normal TSH with a reduced T4 level is classically suggestive of a central cause of hypothyroidism (i.e. reduced hypothalamic or pituitary release of TRH or TSH respectively). However, central hypothyroidism is rare and perhaps a more common cause is the non-thyroidal illness (sick euthyroid) syndrome.
    • Causes of Reduced / Normal TSH with Reduced T4

    • Nonthyroidal illness
    • Recent treatment of hyperthyroidism
    • Central hypothyroidism
    • Congenital TSH or TRH deficiency
    • Assay interference
Last updated on July 29th, 2019
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