May 2015 Product Focus – Answering Your Questions

Editor’s note: This month, Anthony Kurec, MS, H(ASCP)DLM, returns as our clinical expert. Anthony is Clinical Associate Professor, Emeritus, at SUNY Upstate Medical University in Syracuse, NY.

Q: I have a question regarding ESRs. Our hospital recently consolidated with another 20 miles away. There is an extensive courier system in place, but we receive many ESRs that are more than four hours old—the recommended time cut-off. My personal experience is that ESRs become shorter with increasing time from draw, not longer, as some may think. My thinking is to run the samples when received and if the results are elevated, release them, since it is my understanding you are not to draw conclusions about the degree of inflammation by how elevated the ESR is. Then for those that are normal, as long as they are not bordering on abnormal, to release those as well. What are thoughts on this strategy?

A:The Erythrocyte Sedimentation Rate (ESR) is a non-specific test that is primarily associated with the presence of inflammation. The ESR test relies on a property of the red blood cell (RBC) membrane; i.e., the ability to carry a negative electrical charge (zeta potential), thus causing the RBCs to repel from each other. As an anticoagulated blood sample sits, the zeta potential decreases, causing the red cells to aggregate and eventually settle at a particular rate.

There are many factors that influence ESR results. Increased levels of fibrinogen, certain protein globulins, other acute phase reactants, and cholesterol may reduce the zeta potential, resulting in elevated ESR results. Conversely, lecithin, elevated RBCs or WBCs, and albumin may slow the sedimentation rate. Medical conditions such as microcytic anemia, sickle cell anemia, presence of spherocytes and rouleaux, rheumatoid arthritis, chronic infections, Hodgkin’s disease, and multiple myeloma affect results. Age and gender can also influence ESR values. Other technical factors that may alter results are:

Concentration of anticoagulant to blood ratio
Type of anticoagulant, such as heparin, or patients on heparin therapy
Bubbles or a dirty ESR tube
Tilted ESR tube (3^o off center may accelerate ESR by 30%)
Plastic ESR tubes, which may show slightly higher results
Hemolysis.

Time (from the blood draw to set up) and temperature also can impact results. The test should be performed at room temperature (20-25^o C) within two hours of the draw. If there is a delay, the specimen, when collected in EDTA, may be refrigerated (4^o C), thus maintaining its integrity for up to 12 hours. It is important for the refrigerated specimen to come to room temperature before performing the test.

I would be hesitant in employing any strategy based on episodic observations that are not backed up by appropriate research. As noted above, there are many factors that can affect the ESR, and without the proper correlative studies they could lead to reporting less-than-accurate results.

References

Vajpayee N, Graham SS, Bem S. Basic examination of blood and bone marrow, in Henry’s Clinical Diagnosis and Management by Laboratory Methods, 22nd ed. 2011. McPherson RA & Pincus MR, eds. Elsevier Saunders: Philadelphia:519-521.

Lab Tests Online. http://labtestsonline.org/understanding/analytes/esr/tab/glance/ Accessed April 10, 2015.

Q: We closed our moderate-high complexity lab more than two years ago, and are still utilizing the space as a draw station. We will soon be moving to a new space due to construction and are not sure if we need to keep CBC slides from 2010 through 2012. Some drawers are marked abnormal. We routinely made slides for all CBCs but only performed a differential when ordered or when abnormal. How long must we keep them?

A: CLIA has no specific standards regarding the retention of hematology blood films.¹ However, bone marrow blocks and slides are covered under the histopathology retention standard.¹ Also, note that if a laboratory ceases operations, provisions must be made to ensure proper storage of materials for the duration of the set retention time:

Retain histopathology slides for at least 10 years from the date of examination.
Retain pathology specimen blocks for at least two years from the date of examination.
If the laboratory ceases operation, the laboratory must make provisions to ensure that all records and, as applicable, slides, blocks, and tissue are retained and available for the time frames specified in this section.

As with CLIA, Joint Commission also has not set requirements.² However, the College of American Pathologists (CAP) requires hematology slides be retained for at least seven days.³ The National Pathology Accreditation Advisory Council recommends one year for abnormal films and one month for routine ones.⁴ The World Health Organization (WHO) extends retention of blood films to five years.⁵

For some states, there may be specific time requirements. For example, New York State Department of Health requires that routine blood films (or histograms) be retained for six months. Abnormal blood films are to be stored for one year.⁶

It is best to check with your local inspecting agency to ensure appropriate retention times are incorporated into standard operating procedures (SOP).^7-10 The SOP must follow the most stringent guidelines per that agency to ensure inspection requirements are met.

References