General Investigations

1) Thyroid Function Test (TFTs) X

  • fT4
  • fT3
  • TSH

These tests can be abnormal even in some severe non-thyroid diseases, specially ICU patients but then, the patient is clinically euthyroid (sick euthyroid syndrome)

When ordering TFTs, always order free T3 & free T4, not total.

2) Thyroid scan (imaging)

  • With radioactive Iodine or technetium
  • Radioactive substance is taken up by the gland & pics are taken
  • Used to see the “activity” of the gland
  • Normal gland: normal uptake pattern
  • Hyperactive gland: Increased uptake
  • Hypoactive gland: Decreased uptake

3) Ultrasound (imaging): May help to see nodules /cysts in the gland, but cannot differentiate benign from malignant.

4) Fine needle aspiration (needle biopsy)

  • Also called FNA biopsy
  • Done if there is a nodule (benign or malig)