Hypothyroidism

Laboratory tests in 6 weeks

• TSH
• Free T4 (as a reflex test, if TSH remains raised)if neededTSH still above the reference range on repeat: free T4, measured as a reflex test on the same tube, distinguishes subclinical from overt hypothyroidism ^[2,3].

Laboratory tests

• Anti-thyroid peroxidase (TPO) antibodies
• Free T4 (if not already known)if neededFree T4 not measured so far, for example TSH above 10 mIU/L found straight away without a reflex test: it distinguishes overt from subclinical hypothyroidism ^[3].
• anti-thyroglobulin antibodiesif neededNegative anti-TPO with suspected autoimmune hypothyroidism ^[2,3].

Laboratory tests

• TSH

Laboratory tests

• TSH
• Free T4
• Anti-thyroid peroxidase (TPO) antibodies

Follow-up (TSH between 5.5 and 10 mU/L, normal free T4): at 1 year if anti-TPO negative, every 6 to 12 months if positive

• TSH
• Anti-TPO antibodies (if they were negative)if needednon-French guidelineNegative antibodies at baseline: TSH and anti-TPO at 1 year, then at longer intervals if no worsening; no need to measure them again if already positive (TSH alone, ± anti-TPO) ^[8].