Q: Why is my APTT is more than 5 minutes with a clotting time of more than 13 minutes. Earlier Correspondence: QUERY: I am taking prednisolone 15-20 mg for the past three years for pemphigus, a skin disorder. My blood clotting time is now around 14 minutes. Bleeding time is 2 minutes and 5 seconds and PTT is 16 seconds. Can you send this mail to a haematologist and give some medication so that the clotting time can be reduced to 8 minutes? REPLY: Clotting time is a very poor test. A better test is Activated Partial Thromboplastin Time (APTT). If that is prolonged further tests will be required. In the patient even PT appears to be prolonged. However, it is to be correlated to the Laboratorys reference (normal) value. Dr. S.K. Sood

A:A prolonged APTT is generally due to a deficiency of the factors in the intrinsic pathway of coagulation. It can also result from presence of inhibitors of coagulation. The patient has not provided any history of excessive bleeding or any family history of such events. With this abnormal APTT the prolonged clotting time also becomes an important finding. Further laboratory tests that are likely to provide useful information include: APTT=based correction studies, Thrombin time (TT), fibrinogen estimation, and inhibitor screen. One would also like to know about results of liver function tests. If correction studies show deficiency of coagulation factors assays of clotting factors may be indicated. Some clotting factor deficiencies such as that of factor XII are not associated with a bleeding tendency. All in all the APTT of more than 5 minutes should not be ignored and its cause should be investigated in consultation with a haematologist.