I would be interested in learning when a valid hemoglobin should be drawn to evaluate the effectiveness of a transfusion (i.e. 1 hour, 8 hours). If you have references, that would be great.

That's weird. Someone at work asked the same question. I always thought that it was about 1 to 2 hours but I have no documentation to say so. I know to measure post transfusion platelet recovery, the platelet count is measured 1 hour post transfusion.

Years ago I read an article (Lab Medicine I think) where the author stated that to get a truly accurate Hgb post-transfusion (i.e. after the blood volume has had time to adjust) you would need to wait 24 hours! What this tells me is that every test earlier than that has some degree of imprecision, but we all agree that we can't wait 24 hours in a bleeding patient. A less than perfectly accurate answer is still valuable information. Many patient's Hgbs are probably not truly "accurate" as they deal with infusions, diuretics, congestive heart failure and other things that affect blood volume. I think waiting an hour or two is common.

I had same question came from the floor last week. I recall my boss saying 24 hrs but I didn't want to give her incorrect info so I told her to call my boss. My boss is at AABB..I can ask her for any available reference (not before Nov 7th).

Please ask your boss when she returns. Thanks.

Mary

Did your boss have a anwer for this question?

Hi, Mary,

I spoke with my boss today. In non bleeding patient hemoglobin done12 hrs post transfusion (up to 24 hrs) gives correct post increment provided patient is not receiving any other fluid. I do not have reference right now but if I will post here if I find one.

I'm very sorry I don't have a reference, but I do remember reading that there is no "standard" waiting period necessary before taking an H+H on a transfused patient.

Unless the patient is actively bleeding an H+H is usually done with the AM draw after the transfusion. Babs

My experience in reviewing thousands of post transfusion H&H results is that a specimen drawn 30 minutes after transfusion will reflect the hypothetical 1 g/dL boost in hemoglobin. As a one-time chemical engineering student (before I took my first biology class), I studied fluid dynamics. In a system that recirculates ever 3 minutes (the human body), it just doesn't take that long for volume to equalize throughout the system. It may take 24 hours for a capillary result to reflect the transfusion, but not venous draws. Anyone who has ever done an IVP can tell you that. If you don't get that xray done within minutes of infusing the contrast, the kidneys will have cleared it.

BC

Does anyone have any update to the answer of this question?

I was told after the first urination as then the person is fluid-dynamically stable

We want nice clear rules, but sick people are highly variable biologic systems so I doubt there is one answer that is truly correct for all patients. We may have to settle for using the "an hour or 2 is close enough" principle, realizing that some patients will look a bit different the next day. I also read once that it depends on how much fluid is given with the blood and how many units of higher Hct blood are given without extra fluid.

I also read once that it depends on how much fluid is given with the blood and how many units of higher Hct blood are given without extra fluid.

I haven't read that, but, on the other hand, it would seem entirely logical.

My pathologist brought this up the other day. It was believed that for a non-bleeding patient 24hrs post transfusion would give an accurate result. But she found an article that looked at hgb 15mins post, 1hr, 2hr, 24hrs post transfusion and they found that hgb results 15mins post is the same as 24hrs. So the conclusion was that for non-bleeding patients you can get an accurate hgb 15 mins post. I can find the article tomorrow and post the reference.

Thank you in advance for providing that article reference!

I can find the article tomorrow and post the reference.

I apologize, I will post this on Monday.

But for now I found a Q&A on CAPs website:

Q. How long should you wait after a unit of blood has been transfused before drawing a complete blood count, or doing other lab work, to ensure accurate test results?

A. Optimum timing of post-transfusion phlebotomy is critical for ensuring meaningful laboratory testing results, and medical judgment is required in making this determination. Several factors must be considered, including the type and amount of blood product given, purpose of the test (that is, the question it is intended to answer), and clinical setting.

In general, it is best to perform phlebotomy when the patient’s circulatory system is in homeostasis. A patient who is bleeding or undergoing blood product transfusion, or both, is not in a steady state. Whenever possible, samples for laboratory testing should be postponed until bleeding has stopped and transfusion is complete. One obvious exception to this rule, however, would be the setting of massive transfusion, during which monitoring certain laboratory values, such as cell counts and coagulation parameters, is essential to guide ongoing therapy. Variables such as patient blood volume, cardiac output, renal function, and volume of blood products transfused affect how quickly homeostasis is achieved following transfusion.

For the evaluation of post-transfusion increments in hemoglobin, hematocrit, and platelet counts, a practical approach is to draw blood samples within 10 to 60 minutes after completing transfusion, as this time interval is aimed at measuring peak recovery.1 Results determined from blood samples drawn later than 60 minutes post-transfusion are increasingly affected by confounding conditions, such as splenic sequestration, sepsis, and consumption.^1,2 If the intent is to determine the extent of such confounding processes on red cell and platelet counts, one should combine a 10-minute post-transfusion sample with sequential samples drawn at one hour and 24 hours post-transfusion.

Alterations in chemistry test results following transfusion are not usually a concern in the low-volume transfusion setting. However, assay results may be affected for varying periods following transfusion of large amounts of blood products, as seen in massive transfusion, red cell, or plasma exchange—particularly if the recipient has impaired hepatic or renal function. Banked storage of red cells results in elevated plasma levels of hemoglobin, potassium, LDH, and iron in the blood unit that may, particularly in the metabolically impaired patient, be reflected in the post-transfusion laboratory values. In addition, citrate anticoagulant present in blood products may result in transient hypocalcemia in the recipient.³ Therefore, following large-volume transfusions or exchanges, waiting 12 to 24 hours before drawing samples for chemistry assays will provide results that are more reflective of the patient’s underlying metabolic state.

References

1. Choo Y. The HLA system in transfusion medicine. In: McCullough J, ed. Transfusion Medicine. New York, NY: *McGraw–Hill Book Co;1998:401.
   
2. Legler TJ, Fischer I, Dittman J, et al. Frequency and causes of refractoriness in multiply transfused patients. Ann Hematol. 1997;74:185–189.
   
3. Brecher ME, ed. Technical Manual. 15th ed. Bethesda, Md.:AABB;2005;649–650.
   

Rita A. Reik, MD

Pathology Consultants of South Broward

Medical Director/Transfusion Medicine Services

Memorial Healthcare System

Hollywood, Fla

Edited November 30, 201212 yr by Justina
Added CAP website find

Articles:

Elizalde JI, et al.Early changes in hemoglobin and hematocrit levels after packed red cell transfusion in patients with acute anemia. Transfusion. 1997 Jun;37(6):573-6

Wiesen AR, et al. Equilibration of Hemoglobin Concentration after Transfusion in Medical Inpatients Not Actively Bleeding. Ann Intern Med. 1994;121:278-280