Unexpected Results – Lupus and APA

By: Alere Staff
Publication Date: Wed, 07/01/2015

Your blood is a fluid that contains many life-sustaining properties and cells, including red and white blood cells. Your red blood cells carry oxygen rich blood to all your organs and live for about 120 days.1 Your white blood cells are your body’s natural defense against bacteria, viruses and other organisms, including parasites that may cause you harm. They live for only a day or less so your body must constantly make new ones.1

There are times when the body actually fights against itself. When this happens, it is called an auto-immune disease. Antiphospholipid antibody syndrome (APS or APLS) is an example of an autoimmune disease. In this disease, the antibodies in your body which normally circulate in your blood to protect you trigger the development of unwanted blood clots. These clots can occur in the small vessels of your arms or legs or in larger arteries.2 In either blood vessel, the formation of these blood clots puts you at risk.

APS is detected by a blood test and causes a variety of harmful effects including:2

  • Patients with pregnancy loss (9%)
  • Patients with deep vein thrombosis (DVT) (10%)
  • Patients with myocardial infarction (heart attack) (11%)
  • Patients with stroke (14%)
  • Patients with stroke under age 50 (17%)

To prevent the body from forming clots with APS, doctors will often try to prevent the formation of these clots by using an anticoagulant such as warfarin.

Lupus and APS

A condition that is often associated with APS is lupus. If you have lupus, it does not mean that you will get APS and if you have APS it does not turn into lupus.3 Both of these conditions are two distinct things and many people can have one without the other. The antibodies that are found with APS can frequently be found in lupus patients. However, antibody presence does not make a diagnosis.3 Just like with APS, there are more specific tests for lupus that do not rely on antibodies alone. In the end, though, your odds may be higher of getting one if you have the other.3

If you’ve begun taking warfarin for an antibody condition, testing the level of blood clot prevention is important but can be tricky. Testing your blood is done using the traditional method to determine warfarin levels: the prothrombin time test or INR. Some APS specialists recommend higher INR ranges (3.0 – 4.5) if you are a patient with APS.3 It is important to note that some patients with an antibody immune disease may not get a reliable INR test result. It is estimated that one in three patients may get a false (elevated) reading of their anticoagulation level when using a portable INR monitor.4

APS patients who have lupus have an even trickier time getting reliable INR results. These patients need to have their warfarin monitored by different test than by INR, such as by factor II level, chromogenic factor X level or the P&P test.3

Due to these different sets of circumstances associated with APS, the use of a home INR monitor should include close supervision by the patient’s doctor to make sure the measure of blood clot prevention is consistently safe and they have determined the most reliable blood test method for them.4,5 This is done by occasionally taking a venous blood sample from a point-of-care INR monitor and comparing to a reliable reference lab.

Interested in learning more? Check out these articles on similar topics:

  • Unexpected Results – Understanding Your Hematocrit
  • Anemia and Warfarin
  • Neutropenia and Warfarin
  • Unexpected Results – Anemia and Your INR
  • Oral Corticosteroids and Warfarin


  1. American Society of Hematology. Blood Basics. 2015. Retrieved June 17, 2015 from website: http://www.hematology.org/Patients/Basics/
  2. APS Action. About: Antiphospholipid Syndrome. Retrieved June 17, 2015 from website: http://www.apsaction.org/about.html
  3. APS Foundation of America, Inc. August 2006. Frequently Asked Questions. Retrieved June 26, 2015 from website: http://www.apsfa.org/docs/APSFAPrintFAQ11-20.pdf
  4. APS Foundation of America, Inc. May 2013. INR Finger Stick Machines for APS Patients. Retrieved June 17, 2015 from website: http://www.apsfa.org/fingerstick.htm
  5. Moll, S. 1997. Monitoring Warfarin Therapy in Patients with Lupus Anticoagulants. Annals of Internal Medicine.