What causes high INR and low APTT?

High INR and low APTT can be caused by many reasons.

If your INR is in between 0.9 ratio and 1.2 ratio and your APTT is in between 22 seconds and 35 seconds then you need not worry as these are the normal ranges for INR and APTT 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 INR levels include:

• Liver disease
• Vitamin K abnormality
• Decreased or defective factor I (fibrinogen), II (prothrombin), V or X
• Hemophilia A and hemophilia B
• Autoantibody against a specific factor (e.g., factor VIII)

Normal range of INR : 0.9 - 1.2 ratio

Ideal values of INR depending on age :

Age	Ideal INR value
<5 years	0.95
5-10 years	1.003
10-15 years	1.059
15-20 years	1.118
20-25 years	1.181
25-30 years	1.177
30-35 years	1.173
35-40 years	1.17
40-45 years	1.167
45-50 years	1.163
50-55 years	1.159
55-60 years	1.155
60-70 years	1.152
70-80 years	1.149
80-90 years	1.145
90-100 years	1.141
>100 years	1.138

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

Normal range of APTT : 22 - 35 seconds

Ideal values of APTT depending on age :

Age	Ideal APTT value
<5 years	23.232
5-10 years	24.533
10-15 years	25.907
15-20 years	27.358
20-25 years	28.89
25-30 years	30.508
30-35 years	32.216
35-40 years	34.02
40-45 years	33.913
45-50 years	33.807
50-55 years	33.701
55-60 years	33.595
60-70 years	33.489
70-80 years	33.384
80-90 years	33.28
90-100 years	33.176
>100 years	33.072

High INR and low APTT can be caused by a lot of reasons. If you take INR and APTT blood tests and the results are higher than 1.2 ratio for INR and lower than 22 seconds for APTT, 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 INR and APTT Tests Are Done :

If your doctor wants INR and APTT tests on you, you may need to go through these tests. During the INR and APTT 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 INR and APTT Test reports by your pathologist.

Medical References

• MedlinePlus – Prothrombin Time Test and INR (PT/INR)
• Mayo Clinic – Prothrombin time test
• Cleveland Clinic – Prothrombin Time (PT/INR) Test