Hormones & thyroid
Total Thyroxine (Total T4)
About
Measures total thyroxine (T4), the main thyroid hormone. Used to assess thyroid function.
Preparation
Do not eat for 2-3 hours before the test; still water is allowed. Avoid steroid and thyroid hormones 48 hours before the test (as agreed with your doctor). Avoid physical and emotional stress 24 hours before the test. Do not smoke for 3 hours before the test.