Is FT4 thyroid 1.55 normal, high or low? What does Free thyroxine level 1.55 mean?

📅 Medical Review Date: October 25, 2025

Your FT4 thyroid level of 1.55 is a Normal FT4 thyroid level.

Normal FT4 thyroid levels may indicate underlying health problems. The normal range is typically between 0.89 ng/dL and 1.76 ng/dL. If your levels are outside this range, it's important to speak with a healthcare provider. Consulting a doctor is recommended to determine the cause and appropriate next steps.

The normal FT4 thyroid range for men is :0.89 - 1.76 ng/dL

Ideal values of FT4 thyroid depending on age (male) :

Age	Ideal FT4 thyroid value
<5 years	0.904
5-10 years	0.918
10-15 years	0.932
15-20 years	0.946
20-25 years	0.961
25-30 years	0.976
30-35 years	0.991
35-40 years	1.006
40-45 years	1.022
45-50 years	1.038
50-55 years	1.054
55-60 years	1.07
60-70 years	1.087
70-80 years	1.104
80-90 years	1.121
90-100 years	1.138
>100 years	1.156

*Ideal values are calculated based on our database of patient records

Get Advice via Email : Send us your blood test report, and our FT4 thyroid experts will review it. You'll receive a detailed analysis and personalized treatment guidance via email within 12 hours. If you have additional blood test results besides FT4 thyroid, please include those too—an accurate diagnosis often requires a full view of all abnormalities. Upload blood test report now

1,51,150

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A video message on the treatment of your normal FT4 thyroid level

If you want your blood test report to be interpreted by FT4 thyroid specialist, you can upload your report. Our FT4 thyroid expert will provide you with the most accurate interpretation of your blood test results and treatment within 12 hours.Upload blood test report now

Some examples of conditions that increase or decrease FT4 thyroid levels include:

• Autoimmune disease
• A non-functioning thyroid gland
• Thyroiditis
• Diabetes
• Liver disease

Receive world-class medical opinion about your normal FT4 thyroid levels over email.Upload blood test report now

Normal range of FT4 thyroid found among women :0.89-1.76 ng/dL

Ideal values of FT4 thyroid depending on age (female) :

Age	Ideal FT4 thyroid value
<5 years	0.904
5-10 years	0.918
10-15 years	0.933
15-20 years	0.948
20-25 years	0.963
25-30 years	0.978
30-35 years	0.994
35-40 years	1.01
40-45 years	1.026
45-50 years	1.042
50-55 years	1.059
55-60 years	1.076
60-70 years	1.093
70-80 years	1.11
80-90 years	1.128
90-100 years	1.146
>100 years	1.164

If you take a FT4 thyroid blood test and the results are not in the normal range (0.89-1.76 ng/dL), your physician may recommend more tests to figure out the problem. You might also get this test if your physician thinks you have some other disease.

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How the FT4 thyroid Test Is Done :

When your doctor orders a FT4 thyroid test, it involves a straightforward blood draw to measure your FT4 thyroid levels. A pathologist or lab technician will take a small sample of blood from a vein using a needle. Your FT4 thyroid test results are usually available within a few hours.

Medical References

• MedlinePlus – Thyroxine (T4) Test
• Cleveland Clinic – T4 (Thyroxine) Test: What It Is, Function, Purpose & Levels
• MedlinePlus – Free T4 test
• WebMD – What Is a Thyroxine (T4) Blood Test?
• Mayo Clinic – Hypothyroidism (underactive thyroid) - Diagnosis and treatment