Unexpected Results - Anemia and Your INR

By: Alere Staff
Publication Date: Fri, 05/01/2015

What is anemia? There are several types of anemia, but they all have something in common, a low blood count; specifically, a low hemoglobin and hematocrit. These are the parts of your blood that carry oxygen to the tissues, cells, and organs. Hemoglobin and hematocrit work together. When you don’t have enough of one, it usually means you have a deficiency in the other. Many things can affect your hemoglobin and hematocrit levels. If you have too little fluid in your body, as with dehydration, your hemoglobin and hematocrit can go up. If you have too much fluid in your body, as in the case of congestive heart failure which affects how your body gets rid of excess fluid, your hemoglobin and hematocrit levels can go down. The normal adult ranges for hematocrit are 40.7-50.3% in males and 36.1-44.3% in females.

Why is this important? When you monitor your INR with a home testing meter, this may affect your results. Mild to moderate anemia typically will not interfere with an accurate reading. One can be as low as 28% and still be able to rely on the INR meter results. It is when the hematocrit levels drop to about 25% that this can cause an inaccurate result; not only with the meter, but also a blood draw.

You can be anemic and not experience any symptoms, but some common signs to be aware of are fatigue, dizziness, leg cramps, and pale skin. If you are experiencing any of these symptoms, you should tell your doctor immediately, especially if your INR meter has been giving inaccurate results. He or she may want to check your hematocrit levels.

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References:

  1. Reviewed by Melinda Ratini, DO, MS on March 04, 2015 on website:  http://www.webmd.com/a-to-z-guides/understanding-anemia-symptoms.  
  2. Hoel, Robert, et al. Correlation of Point-of-Care International Normalized Ratio to Laboratory International Normalized Ratio in Hemodialysis Patients Taking Warfarin. Clin J Am Soc Nephrol. 2009 Jan; 4(1): 99–104 on website: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2615705/.  
  3. Gersten M.D., T. Hematocrit. Medline Plus. February 24, 2014 from web site: http://www.nlm.nih.gov/medlineplus/ency/article/003646.htm.
  4. Correlation of Point-of-Care International Normalized Ratio to Laboratory International Normalized Ratio in Hemodialysis Patients Taking Warfarin; Robert W. Hoel* † , Robert C. Albright † ‡ , Lisa K. Beyer § , Paula J. Santrach † § , Donna L. Magtibay ‖ , Stephanie L. Everson ‖ , Robert D. McBane † September 3, 2008 from website:  http://cjasn.asnjournals.org/content/4/1/99.full.