LabSense

Thyroid Tests Explained: TSH, Free T4 & Antibodies

8/17/2025

The pituitary releases TSH which drives thyroid hormones T4/T3. Read tests together and use your lab's reference intervals.

Common patterns

  • Primary hypothyroid: high TSH + low free T4.
  • Subclinical hypothyroid: high TSH + normal free T4 (repeat and check antibodies/symptoms).
  • Primary hyperthyroid: low TSH + high free T4/T3.
  • Central: low/normal TSH + low free T4 — clinician review.
  • Sick-euthyroid: illness/meds may distort tests — avoid over-interpretation.

Educational next steps

  1. Borderline results: repeat in 6–8 weeks.
  2. Antibodies: TPO/Tg (autoimmune); TRAb/TSI (Graves pattern).
  3. Medication education (not a prescription): levothyroxine is standard; typical adult starting ~1.6 mcg/kg/day but individualized by a clinician; separate from iron/calcium.

Disclaimer: Educational information only — not a diagnosis, treatment, or prescription.

Educational information only — not a diagnosis, treatment, or prescription.