GHNHSFT Clinical Biochemistry Thyroid Function Testing Strategy Clinical

GHNHSFT Clinical Biochemistry - Thyroid Function Testing Strategy Clinical Details Provided: Patient NOT on Thyroid medication OR Patient on T 4 Patient under 18 OR Patient is pregnant OR Suspected/Known Pituitary disorder OR Treated Thyroid Cancer Patient Tests Required: TSH ONLY TSH AND FT 4 Patient on T 3 TSH AND FT 3 TSH result interpretation/further testing : 0. 2 – 6. 0 mi. U/L No further tests added and results not reviewed. Free T 4 result interpretation/further testing: TSH Result interpretation/further testing: Not on medication and >5. 5 mi. U/L but <10. 0 mi. U/L Borderline TSH indicates possible early hypothyroidism / subclinical hypothyroidism. Suggest repeat in 3 -6 months. Any result outside of reference range is reviewed by the duty biochemist < 0. 2 mi. U/L The TSH result suggests overreplacement with thyroid medication. Consider dose reduction if clinically suitable to avoid possible long-term side effects. Please note: if measurement of free T 3 levels is desired, a sample should be taken shortly before next dose of medication is administered. This is to ensure consistency of testing in the face of the wide variability in post-dose free T 3 levels. Not on medication and >10. 0 mi. U/L FT 4 added on by Biochemist. If suppressed, result consistent with hypothyroidism. If not, Borderline TSH indicates possible early hypothyroidism / subclinical hypothyroidism. Suggest repeat in 3 -6 months. Not on medication and <0. 2 m. IU/L Lab adds FT 4 and FT 3. If free hormones raised, indicative of Hyperthyroidism. Biochemist may add Thyroid receptor antibodies, or suggest repeat with TRAb after 6 weeks, depending on clinical circumstance. On thyroxine and >5. 5 mi. U/L The result(s) are consistent with inadequate thyroid hormone replacement, poor absorption OR possible non-compliance On thyroxine and <0. 06 mi. U/L Lab adds FT 4 and comments - TSH result suggests over replacement with thyroxine-consider dose reduction if clinically suitable to avoid possible long-term side-effects. If FT 4 > 29. 9 pmol/L then FT 3 is added. Comments may also be added by the Duty Biochemist as relevant to the information available, or after discussion with the requesting clinician. Please note – in patients with Pituitary dysfunction, TSH may not reflect thyroid function in this patient, therefore thyroxine dose should only be adjusted on the advice of an endocrinologist. 0. 2 – 5. 5 mi. U/L: TSH within reference range which suggests adequate dose. Please note: it can be misleading to measure free T 3 in patients receiving triiodothyronine because of the wide variability seen in free T 3 values post-dose. Comments may also be added by the Duty Biochemist as relevant to the information available, or after discussion with the requesting clinician. Patient on Carbimazole OR Patient on Amiodarone TSH, FT 4, FT 3 All results reviewed. Comments may also be added by the Duty Biochemist as relevant to the information available, or after discussion with the requesting clinician.