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Optimal - The Blog

January 3, 2022

Thoughts on a lower optimal range for total WBCs

Elevated WBCs are associated with infection and inflammation as well as several chronic diseases. We are currently reviewing optimal WBC ranges and incorporating research regarding a potential optimal range of 3.5-5.9 k/cumm.

We are looking at a revision of the optimal range for WBCs though not down to a level as low as 3.11 k/cumm as was mentioned in a study out of Taiwan (Huang 2007). The study, using data from a health check program, found a significant association between white blood cell (WBC) counts and C-reactive protein as well as neutrophil and monocyte percentage, suggesting that higher WBCs are associated with increased inflammation which is widely accepted.

Researchers also point out that increased WBCs are associated with non-infectious conditions including hypertension, cardiovascular morbidity, obesity, hypertriglyceridemia, lower HDL, hyperinsulinemia, and smoking. The study found that the mean WBC for those with the lowest CRP value of less than 1 mg/L were associated with the lowest WBC mean of 5.97 k/cumm. The study extended its recommended range 2 standard deviations out from 5.97 to come up with a proposed range for WBCs of 3.11-8.83 k/cumm. Tightening that range to just 1 standard deviation from the mean would be a range of 4.54-7.4.

Huang et al. note additional research confirming an increased risk of cardiovascular disease with WBCs above 8.1 compared to below 6.6 in Caucasian males, and increased risk in African Americans with WBC above 7.0 compared to below 4.8.

However, in the 44-year Baltimore Longitudinal Study of Aging, researchers concluded that those with a WBC below 3.5 or above 6 had a significantly greater risk of mortality compared to those with WBCs 3.5-6 (Ruggiero 2007).

  • A WBC count of 6-10 was associated with a 30-40% greater risk of mortality
  • WBCs below 3.5 was associated with a 3-fold increase in mortality
  • WBCs above 10 were associated with 2-fold increased mortality compared to a WBC count of 3.5-6.
  • Those participants who died were more apt to smoke, be less physically active, and have a worse cardiovascular health profile than survivors.

Further evaluation of the predictive value of the complete blood count in assessing cardiovascular risk confirmed that cardiac patients with a WBC count of 6 or below had the lowest mortality. Lower values for hematocrit, MCV, MCHC, RDW, and platelets were also associated with a reduced risk of mortality (Anderson 2007).

Therefore, our most likely revised optimal WBC range will be 3.5-5.9 k/cumm.


Anderson, Jeffrey L et al. “Usefulness of a complete blood count-derived risk score to predict incident mortality in patients with suspected cardiovascular disease.” The American journal of cardiology vol. 99,2 (2007): 169-74. doi:10.1016/j.amjcard.2006.08.015

Huang, Zei-Shung et al. “Revision in reference ranges of peripheral total leukocyte count and differential leukocyte percentages based on a normal serum C-reactive protein level.” Journal of the Formosan Medical Association = Taiwan yi zhi vol. 106,8 (2007): 608-16. doi:10.1016/S0929-6646(08)60017-0

Ruggiero, Carmelinda et al. “White blood cell count and mortality in the Baltimore Longitudinal Study of Aging.” Journal of the American College of Cardiology vol. 49,18 (2007): 1841-50. doi:10.1016/j.jacc.2007.01.076


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