T4 on your report
Often shown in one of two ways:
- free T4 (FT4) in ng/dL
- total T4 in µg/dL
Labs set their own range, and pregnancy and severe illness can also change it. Read it with your TSH and your doctor's advice.
Want the numbers? TSH normal range for women, including pregnancy.
T4: the main hormone made by your thyroid gland in the front of your neck.
What T4 tells your doctor
Thyroid hormones affect nearly every organ, including your heart rate, digestion, weight and mood.
A low T4 often goes with an underactive thyroid, sometimes caused by Hashimoto's disease, which can bring:
- tiredness
- weight gain
- constipation
- feeling cold
A high T4 can point to an overactive thyroid, such as Graves' disease. Free T4 is the most useful version for most people.
What moves your T4
Abnormal T4 is managed by your doctor, often with medicine, and food is not a substitute.
Day to day, these help you feel your best:
- regular balanced meals
- enough protein
- fibre from vegetables and whole grains for digestion
- iodised salt in normal amounts
- regular activity and good sleep
Birth control pills, steroids, other medicines and iodine-rich products can affect the result, so tell your doctor about everything you take.
The first call is free
Tell Puja what's going on and she will tell you honestly whether she can help.
Checked against: MedlinePlus: Thyroxine (T4) Test. General information, not medical advice.
Related words
TSH (thyroid stimulating hormone)T3Anti-TPO antibodiesHypothyroidismHashimoto's thyroiditisHyperthyroidism
Where it comes up
Read next: Thyroid diet: eating well with an underactive thyroid.
A question about T4?
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