The T7 Index is the product of T4 x T3 Uptake, divided by 100. it is also known as the Free Thyroxine Index.
T7= (T4 x T3-Uptake)/100
This calculation is an attempt to correct for variations in thyroxine binding proteins.
Result interpretation:
| Disorder | Total T4 | T3 Uptake | T7 |
| Primary hypothyroid | Decreased | Decreased | Decreased |
| Secondary hypothyroid | Decreased | Decreased | Decreased |
| Hyperthyroid | Increased | Increased | Increased |
| T3 Toxicosis | Normal | Normal | Normal |
Reference ranges:
T7 will usually be decreased in patients with hypothyroidism. It may also be low in patients with non-thyroid illness.
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T7 will usually be elevated in patients with hyperthyroidism.
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5-Methyltetrahydrofolate, Adiponectin, Albumin/Creatinine Ratio, Random Urine, Anti-Thyroglobulin ab. (0-39), C-Peptide, Serum, C-Peptide, Ultrasensitive (Endocrine Sciences), Ceruloplasmin, Creatinine, Random Urine, Cyclic AMP, Plasma, Dihydrotestosterone (female), Dihydrotestosterone (male), Estimated Average Glucose (eAG), Free Androgen Index, Free testosterone, Free Testosterone, Direct (Female), Free Testosterone, Direct (Male), Free Thyroxine, Free Thyroxine Index, Fructosamine, Glutamic Acid Decarboxylase, Glycated Serum Protein (GSP), Hemoglobin A1c (HbA1c), HOMA-B, HOMA-IR, HOMA-S, Homocysteine, Insulin (Fasting), Insulin Antibody, Insulin-Like Growth Factor I (IGF-1), Iodine, Serum/Plasma, Nonesterified Fatty Acids (Free Fatty Acids), Parathyroid Hormone (PTH), Serum, Pregnenolone, Proinsulin, Reverse T3, Serum, Sex Hormone-Binding Globulin (SHBG), T3, Free (Triiodothyronine), T4, Free, T4, Total (Thyroxine), T7 Index, Testost., % Free+Weakly Bound, Testost., % Free+Weakly Bound (female), Testost., F+W Bound (female), Testosterone, Testosterone (Female/Child), Testosterone, bioavailable, Testosterone, Serum (Female), Thyroglobulin, Thyroglobulin Antibodies (0 - 1 IU/L), Thyroid Peroxidase Antibodies (Anti-TPO Ab), Thyroid Stim Immunoglobulin, Thyroid-Stimulating Hormone (TSH), Thyrotropin Receptor Ab, Serum, Thyroxine-binding globulin, TBG, TMAO (Trimethylamine N-oxide), Total T3, Tri iodothyronine (T3) Uptake, Triiodothyronine, Serum, TSH Receptor Antibody (TBII)
