What causes high FT4 thyroid and low Cystatin c?

High FT4 thyroid and low Cystatin c can be caused by many reasons.

If your FT4 thyroid is in between 0.89 ng/dL and 1.76 ng/dL and your Cystatin c is in between 0.62 mg/L and 1.03 mg/L then you need not worry as these are the normal ranges for FT4 thyroid and Cystatin c respectively. But if your levels are lesser or greater than the above values, then there may be some problem in your body.

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

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

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

Ideal values of FT4 thyroid depending on age :

Age	Ideal FT4 thyroid value
<5 years	0.92195
5-10 years	0.95505
10-15 years	0.98934
15-20 years	1.02486
20-25 years	1.06165
25-30 years	1.09976
30-35 years	1.13924
35-40 years	1.18014
40-45 years	1.22251
45-50 years	1.2664
50-55 years	1.31186
55-60 years	1.35896
60-70 years	1.40775
70-80 years	1.45829
80-90 years	1.51064
90-100 years	1.56487
>100 years	1.62105

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

Normal range of Cystatin c : 0.62 - 1.03 mg/L

Ideal values of Cystatin c depending on age :

Age	Ideal Cystatin c value
<5 years	0.642
5-10 years	0.665
10-15 years	0.689
15-20 years	0.714
20-25 years	0.74
25-30 years	0.767
30-35 years	0.795
35-40 years	0.824
40-45 years	0.854
45-50 years	0.885
50-55 years	0.917
55-60 years	0.95
60-70 years	0.984
70-80 years	1.019
80-90 years	1.018
90-100 years	1.017
>100 years	1.016

High FT4 thyroid and low Cystatin c can be caused by a lot of reasons. If you take FT4 thyroid and Cystatin c blood tests and the results are higher than 1.76 ng/dL for FT4 thyroid and lower than 0.62 mg/L for Cystatin c, your physician may recommend more tests to figure out the problem. You might also get these tests if your physician thinks you have some other disease.

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How the FT4 thyroid and Cystatin c Tests Are Done :

If your doctor wants FT4 thyroid and Cystatin c tests on you, you may need to go through these tests. During the FT4 thyroid and Cystatin c blood tests, a pathologist will put a needle into your veins and take out a small quantity of blood. A pathologist is a physician in the medical field who thoroughly studies the causes and effects of disease. Within a few hours you will get your FT4 thyroid and Cystatin c Test reports by your pathologist.

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