What is T7 Index?

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.


T7 will usually be elevated in patients with hyperthyroidism.


T7 will usually be decreased in patients with hypothyroidism. It may also be low in patients with non-thyroid illness.

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:

  • males: 1.22 – 4.86
  • females: 0.99 – 4.71

thyroid panel t7 index

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: