Interpreting Thyroid Function Tests

Question 1

Low TSH

High Free T4

Answer 1

Thyrotoxicosis

(e.g. Grave’s disease)

Question 2

High TSH

Low Free T4

Answer 2

Primary hypothyroidism

Question 3

Low TSH

Low T4

Answer 3

Secondary hypothyroidism

(Replacement steroid therapy is rqeuired prior to thyroxine)

OR

Sick Euthyroid Syndrome (Now called Non-Thyroidal illness)

Common in hospital patients.

T3 will also commonly be low.

Question 4

High TSH

Normal Free T4

Answer 4

Subclinical hypothyroidism

or

Poor compliance with thyroxine

Question 5

Low TSH

Normal Free T4

Answer 5

Steroid therapy

Question 6

Answer 6