Free T3 and thyroid
Reads: Thyroid
About 80% of it is made outside the thyroid, in your tissues. That is why the standard blood test can read normal while the hormone that does the work is low.
What this marker reads
Active thyroid hormone (T3) — the signal that sets metabolic rate, temperature and energy availability.
What a named body publishes
Each line below is the sentence the issuing body wrote, carried with its own identifier. Nothing here interprets your result — it states what was published, for whom, and by whom.
TSH
“In the NHANES III disease-free reference population the paper reports 'the 95% TSH reference limits between 0.45 (0.42-0.47) mIU/liter and 4.12 (3.94-4.45) mIU/liter' (values in parentheses are the 95% confidence intervals on each limit).”
Serum TSH, T4, and Thyroid Antibodies in the United States Population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III) · The Journal of Clinical Endocrinology & Metabolism · 2002 PMID 11836274
Total T4
“Total thyroxine (T4) 2.5th-97.5th percentile in the same NHANES III disease-free reference population: 65.2 (95% CI 64.3-66.8) to 162.8 (95% CI 155.8-165.8) nmol/liter.”
Serum TSH, T4, and Thyroid Antibodies in the United States Population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III) · The Journal of Clinical Endocrinology & Metabolism · 2002 PMID 11836274
“The same total T4 interval in the conventional units the paper gives alongside SI: 5.1 to 12.6 µg/dl.”
Serum TSH, T4, and Thyroid Antibodies in the United States Population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III) · The Journal of Clinical Endocrinology & Metabolism · 2002 PMID 11836274
Your laboratory reads your result against its own assay, and this page does not do that for it. What is above is what a named body published and for whom; the machinery this marker reads is set out on its pathway page, and the formulas witnessed on it are below.
The machinery behind it
What raises this marker and what it goes on to move — each edge carried with its own study — is set out in full on its pathway page: Thyroid →
Formulas that modulate it
Each formula page names this pathway and carries the study behind its claim.
Build a combo from your panel
Open the bloodwork builder and select every marker your lab flagged — it covers the most machinery with the fewest formulas.