Research Blog

May 24, 2023

Two Blood Draw Results: It is a Question of Timing


Does it matter if all lab tests were done at different times? For example, a client had a CMP-14 done on March 10th, 2023, and then in May, they had a CBC with differential done. Can I add the May values to the report that was done in March?


Ideally, biomarker results should be from a single blood draw, preferably at the same lab and under the same conditions as past labs that are to be used for comparison. Results of different panels from different blood draw dates may confound results.

The handling and processing of blood samples may vary somewhat from lab to lab and from date to date. Therefore, using a single blood draw for the evaluation of multiple biomarkers is preferred in order to control for these variables.

Some biomarkers may change acutely with inflammation, infection, or stress, or even may depend on the life span of a red blood cell which can vary on average from 60 – 120 days (Pagana 2021, Beltran 2016).

With that said, if you are only able to obtain the results of one set of biomarkers from one day and another set of different biomarkers from another day, you can still evaluate each set as part of a comprehensive functional blood chemistry analysis. It is important to acknowledge that the results are from two different blood draws and preferably obtain a single draw for future analysis. As always, comparing any current results to past results for each biomarker is the optimal approach to identify true trends toward or away from dysfunction.

Here is a related comment from a past ODX post:

If monitoring a specific condition or set of biomarkers, the frequency of monitoring may vary. For example, if monitoring red blood cell biomarkers, including a CBC or hemoglobin A1C, labs should be rechecked in 3-6 months as the average life span of a red blood cell is 120 days.

If an individual has blood loss or an acute condition requiring closer monitoring, labs must be obtained more frequently. Remember that having blood drawn or even anticipating it can be stressful, so it is important not to over-test. This applies to fingerstick blood testing as well (Lorenz 2021).

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Beltran Del Rio, Manuel et al. “Glycated Hemoglobin, Plasma Glucose, and Erythrocyte Aging.” Journal of diabetes science and technology vol. 10,6 1303-1307. 1 Nov. 2016, doi:10.1177/1932296816659885

Lorenz, Tierney K. “Autonomic, endocrine, and psychological stress responses to different forms of blood draw.” PloS one vol. 16,9 e0257110. 3 Sep. 2021, doi:10.1371/journal.pone.0257110

Pagana, Kathleen Deska, et al. Mosby's Diagnostic and Laboratory Test Reference. 15th ed., Mosby, 2021.

Pedlar, Charles R et al. “Blood Biomarker Profiling and Monitoring for High-Performance Physiology and Nutrition: Current Perspectives, Limitations and Recommendations.” Sports medicine (Auckland, N.Z.) vol. 49,Suppl 2 (2019): 185-198. doi:10.1007/s40279-019-01158-x 

Sikaris, Kenneth A. “Enhancing the Clinical Value of Medical Laboratory Testing.” The Clinical biochemist. Reviews vol. 38,3 (2017): 107-114. 

Tag(s): Biomarkers

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