TRH stimulation test

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The administration of TRH produces a rise in serum TSH 20 minutes after injection 200 mcg IV. This test is indicated to exclude hyperthyroidism in borderline cases or where measures of serum T4 and T3 are equivocal:

  • a rise in TSH to outside the normal basal range excludes hyperthyroidism
  • an absent or impaired TSH response is consistent with
    • hyperthyroidism
    • Grave's ophthalmology
    • some euthyroid multinodular goitres
    • subclinical toxic adenoma
    • de Quervain's thyroiditis
    • acromegaly and hypopituitarism
    • Cushing's disease
    • TSH may also be impaired if too much thyroxine is given to hypothyroid patients

The TRH stimulation test has largely been replaced by highly sensitive TSH assays.

Last reviewed 07/2021