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Canine Autoimmune Hemolytic Anemia (AIHA & IMHA) - PCV vs HCT
| HI Everyone, I haven't written for a while regarding Mac, my Springer Spaniel that was diagnosed in May of this year with IMHA. He's been doing really well, and has been slowly weaning off the prednisone. He was originally on 50 mg,and in the last three months my vet has been dropping it 5mg every two or three weeks. After today's CBC results it was reduced another 5mg to 20 mg a day! He's obviously much more comfortable and we are thrilled. A real mystery, though, is his PCV level vs his hematocrit level. His PCV three weeks ago was 35, and his HCT was 26. Today his PCV was 36, his HCT was 24. My vet has had her machine checked, sent the blood to an outside lab, etc, and there's still a big discrepency in the two numbers. I know that the PCV is the one you should trust, so I can't say I'm worried, just perplexed. Has anyone had a similar experience? Any thoughts? Mac's activity level is very energetic, beautifully pink gums, eats like a hog. Jane |
| Jane |
| I am confused about these terms. From what I understand the PCV is the one they spin and seperate and yet every time I go to the vet and have this done he calls this the HCT. Soo regarding the spin vs bloodwork one, YES, there is always a big difference and my vet seems to get embarrased because he cant explain the swings in the 2 11/1 Wylie Spin (PVC?) was 27, the bloodwork - 22 Saturday, Her PVC was 47 and the bloodwok was 36. he always goes by the PVC and not the bloodwork one because it has been off from day 1. Laurie |
| Laurie CA |
| Jane, This has been the case every time we have a cbc. I always have the pcv done separately and it is always around 37-39, while the hct is lower. We saw the specialist earlier this year and he noted to me that he wasn't happy with the lower hct on my vet's cbc test forms. When he came back later with his own blood test results, he told me never mind, your vet's machine must be mis-calibrated, Chance's pcv is fine. What may also play a factor right now is that the red blood cells that Mac is making may not be perfect, they may be a bit smaller, or there may be a large number of reticulocytes in circulation. These are immature red blood cells. The automated analyzer can sometimes have trouble reading all these things and misinterpret what is going on. Your vet should be taking a smear of blood and examining it under a microscope occasionally to see if this is the case. Please, if you can, tell me what the number of red blood cells rbc and the number for the hemoglobin on your test results. If the red blood cells Mac is producing are high quality and carry enough hemoglobin, that would account for his clinically good condition. I have been doing more studying about this and discovered that the American Red Cross actually uses the hemoglobin levels as an indicator of anemia rather than the pcv or hct. I am not sure if we can apply that to canines or not. But as I have been thinking about it, it certainly makes a lot of sense to me. So, in short, don't worry too much. That pcv is the visual reading. It's a true ratio of the red stuff to the white stuff. The automated analyzer's results are based on shapes, colors, types of cells etc all read by a computer. Its value is that it can sort out special cell types that are critical to the diagnosis of AIHA. It could show if there were spherocytes for instance. I am going to try to get some help about this from my vet this week as it seems to be a very big question a lot of us have. Dr C. has an encyclopedic brain and will have an answer I am sure. Love her. patrice |
| Patrice NYS |
| My vet called me with Mac's results yesterday and I haven't picked up the actual paperwork yet, so I'll go off of his blood work from three weeks ago and assume that things have shifted slightly for the better since his PCV went up. Hemoglobin--12.6 RBC--4.18 Platelets--369 everything else was in the normal range. His retic was .8%, but has always bounced between that and 4%. Total protien--7.6 Interestingly enough, Mac has never shown any spherocytes in his blood. That's Mac in a nutshell. I'll be in Colorado on business for the next three days and will not have access to my computer, but will be interested in any more thoughts on this. Thanks everyone! Jane |
| Jane MN |
| Jane, The hemoglobin is lowish at 12.6, as low normal is 14. The RBC are lowish at 4.18, as low normal is 5.6. Platelets fall within normal limits. Total protein falls wnl. So there are a lower number of RBC. And there is a lower than avg hemoglobin amount. However, the numbers are not extremely low and the best indicator would be to compare this current test with past tests to see if there has been an upward rise in both numbers. This would indicate improvement. Anemia is graded as a relationship between the number of red blood cells and the number of reticulocytes. This is called the absolute reticulocyte number. Taking 4.18 RBC (in millions) times .8% reticulocytes gives us a number of 334,000 reticulocytes. This is actually indicative of a moderate regenerative response. (moderate = 300,000, marked = 500,000) This measure is currently the most favored marker used. There are two other measurements that can be use called the CRP corrected reticulocyte percentage and the RPI reticulocyte production index. CRP is used to compare the dog's hematocrit to a normal hematocrit. Retic% times (patient's hct/normal hemtocrit). The difficulty with this is that normal may be different for each dog but is usually considered 45 for this. Some dogs require a very high hct, while others are quite fine with a lower one. Chance falls into the low range. Computing this formula with either Mac's hct of 24 vs his pcv of 36 gives very different numbers! Using the pcv of 36 gives us a number of .64. This means that the actual % of reticulocytes is considered to be .64% rather than .8%. The normal reference is >1% in dogs. The RPI is CRP/Reticulocyte lifespan in days. Using your CRP of .64/1.5 days (from a chart indicating that 35 = 1.5 days) gives us a number of .426. What this is saying is that reticulocytes *normally* mature in the marrow and are not in general circulation for the most part. When there is anemia, there is a demand by the body for more RBC. The marrow will send out reticulocytes early to cover this demand. They still need to mature so they spend a few days doing this while in general circulation. In essence this measurement tells us whether or not there is a good red blood cell production occuring. This number should be >1%. In your case it is .426% I know this seems very complicated but I am really trying to define whether Mac is regenerating at a good rate or not. In essence making enough RBC in response to a demand by the body for more oxygen. The hemoglobin carries the O2. So more RBC = more HgB = lower demand for reticulocytes. Lower HgB = demand for more reticulocytes. Is Mac sufficiently regenerative at this point? Comparing multiple CBC's will give you a better picture of that. Chance had similar numbers and a similar good clinical response. What I think was happening with Chance was that he was having to make blood all over again, after not having made it for awhile, and that process was not perfect. It is affected by many things, for instance proper nutrition and correct stimulation by hormones from the kidneys. Dr. Dodds talks about how important the thyroid is to this process too. If this were me I would watch the numbers of reticulocytes very carefully. There should be more in circulation in general than you are seeing. At one point Chance had a number over 5%. This is highly regenerative. Mac seems to be recovering clinically so the next CBC would be very telling. my best patrice |
| Patrice NYS |
This thread was discussed between 08/12/2008 and 09/12/2008
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