Transcription of High Total or Free T4 (analogue method) …
1 Figure. Differential Diagnosis of Hyperthyroxinemia and Nonsuppressed TSH High Total or free T4 ( analogue method) Normal/high TSHRule out levothyroxine therapy, acute non-thyroidal illness, and drug effectsNormal DFT4 Normal/high TSHS uspect resistance to thyroid hormone (RTH)Positive RTH very likelyTSH-secreting pituitary adenoma probableTSH not suppressedNegative Alpha subunit:TSH ratio >1 Alpha subunit:TSH ratio <1 Hyperthyroxinemianot confirmedPossible RTH without THRB mutation (15% of cases)Suspect TSH-secreting pituitary tumorSuspect analytical interferenceNo abnormalities detectedHigh DFT4 Normal/high TSHC ontent reviewed 12/2012 TSH partially suppressedFree T4, Direct Dialysis (DFT4) and TSHQ uest, Quest Diagnostics, any associated logos, and all associated Quest Diagnostics registered or unregistered trademarks are the property of Quest Diagnostics.
2 All third party marks - and -are the property of their respective owners. 2012 Quest Diagnostics Incorporated. All rights reserved. Analytical interference in the direct dialysis free T4 and TSH assays could result from benign conditions such as abnormal T4 binding proteins (eg, familial dysalbuminemic hyperthyroxinemia), autoantibodies to T4 or TSH, or exposure to mouse monoclonal antibodies resulting in production of human anti-mouse antibodies (HAMA). Adapted from references 1 and toThyroid Hormone (RTH)Mutation Analysis(THRB gene mutation)T4 AntibodyT4 Binding ProteinsTSH AntibodyTSH, with HAMA TreatmentConsider THRB mutation testing on 1st degree relativesAlpha Subunitand TSHT3 Suppression Test (unless contraindicated)
