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Importance of WBC /Leukocyte Range to Understand Aging /Mortality /Disease Condition

The complete blood count (CBC) is a very common blood test. It evaluates the three major types of cells in blood: red blood cells, white blood cells, and platelets.Three tests - measuring red blood cell (RBC) count, hemoglobin, and mean (red) cell volume (MCV) - provide information about the red blood cells, which carry oxygen from the lungs to the rest of the body. These tests are usually done to test for anemia, a common condition that occurs when there aren't enough red blood cells.

A complete blood count (CBC) or full blood count (FBC) or full blood exam (FBE) or blood panel is a test requested by a doctor or other medical professional that gives information about the cells in a patient's blood.The cells that circulate in the bloodstream are generally divided into three types: white blood cells (leukocytes), red blood cells (erythrocytes), and platelets or thrombocytes. Abnormally high or low counts may indicate the presence of many forms of disease, and hence blood counts are amongst the most commonly performed blood tests in medicine.

Complete blood count (CBC), which includes:

white blood cell count (WBC)
red blood cell count (RBC)
platelet count
hematocrit red blood cell volume (HCT)
hemoglobin concentration (HB) - the oxygen-carrying pigment in red blood cells.
differential blood count

Also part of the CBC is the blood differential test that measures the relative numbers of white blood cells (WBCs) in the blood. WBCs (also called leukocytes) help the body fight infection. These cells are bigger than red blood cells, and there are far fewer of them in the bloodstream. An abnormal white blood cell count may indicate that there is an infection, inflammation, or other stress in the body. For example, a bacterial infection can cause the WBC count to increase or decrease dramatically.Also to aid in diagnosing anemia and other blood disorders and certain cancers of the blood; to monitor blood loss and infection; to monitor a patient's response to cancer therapy, such as chemotherapy and radiation.

The primary function of white blood cells, or leukocytes, is to fight infection. There are several types of white blood cells and each has its own role in fighting bacterial, viral, fungal, and parasitic infections. Types of white blood cells that are most important for helping protect the body from infection and foreign cells include the following:

neutrophils
eosinophils
lymphocytes
monocytes
granulocytes

A low white blood cell count (leukopenia) can lead to infection, a dangerous and sometimes deadly complication of cancer treatment.With a low white blood cell count and, in particular, a low level of neutrophils (neutropenia), a type of white blood cell that fights intruders, you're at higher risk of developing an infection. If you develop an infection when you have a low white blood cell count, your body can't protect itself from the infection.

In non-pregnant women with bacterial vaginosis (BV), elevated WBC counts were associated with VVC, trichomoniasis, chlamydia, or gonorrhea. Vaginal WBC counts had moderate sensitivity and specificity, a low positive predictive value, and a high negative predictive value for vaginal and cervical infections, and have a potential role in assessing STD risk and need for empiric therapy in more resource limited, high STD risk settings that rely predominately on syndromic management for cervical infections.

Neonatal sepsis occurs in 1 to 8 cases of all live births, but is 25 times more likely in low birthweight infants (<1500g) and 50-75 times more likely in very-low-birth-weight infants (500-1000g).No one predictor of sepsis is both sensitive and specific. The most sensitive predictors are increased ratio of bands and either high or low total neutrophils. The most specific predictors are thrombocytopenia, neutrophilia or neutropenia or presence of >2 degenerative changes in the neutrophils on histology.

Men and women with above-normal white blood cell counts could face an increased risk of death at an earlier age, particularly from cardiovascular disease, a new study suggests.

People with normal white cell counts may not be out of danger, either, since individuals on the high end of the normal range were also at increased risk of illness and death, the team of Italian and American researchers said.

"The risk of cardiovascular mortality increased progressively with increasing white blood cell counts," noted study lead author Dr. Carmelinda Ruggiero from the U.S. National Institute on Aging. And, "the increased risk of mortality associated with high white blood cell (counts) was maintained over 40 years of follow-up," she added.

But the researchers stressed that they have not yet confirmed a cause-and-effect link between higher white blood cell counts and illness risk. It remains unclear whether an elevated count helps trigger serious disease, or whether these cell counts rise naturally after illness.

And one expert said it's too early to make any changes to practice based on the findings.

"The findings are interesting and help to bolster that inflammation status is involved in the biology of many chronic diseases, but the findings do not suggest specific screening or treatment would be advisable," said Dr. Mary Cushman, director of the thrombosis and hemostasis program at the University of Vermont and Fletcher Allen Health Care in Colchester, Vt.

Generated by the bone marrow and spread throughout the body, white blood cells (WBC) -- also called leukocytes -- are the immune's system key weapon against infectious disease. In the absence of disease, they normally make up just one percent of a person's blood.

According to the U.S. National Institutes of Health, a simple blood test can easily determine whether a patient's WBC count falls within the normal range of 4,500 to 10,000 cells per microliter of blood.

While a below-normal WBC count may indicate bone marrow failure and/or liver and spleen disease, illness or invasion by a foreign body typically provokes a rise in white blood cells. Physical or emotional stress and certain chronic medications can also prompt an increase.

In their study, Ruggiero and colleagues examined data collected during a multi-decade study on aging. They tracked the medical histories of more than 2,800 men and women from the Baltimore and Washington, D.C., area.

Participants were healthy at the time of their entry into the study. WBC counts, body mass indexes, and cholesterol and blood pressure levels were tallied during biannual medical evaluations.

An analysis of death records revealed that those participants who died during the study period had higher WBC counts than those who survived through to 2002.

The finding applied to all patients regardless of their initial baseline WBC count, and held regardless of gender, age at death, or year of death. However, women tended to have significantly lower WBC levels than men.

Patients who had WBC counts between 3,500 and 6,000 cells per microliter of blood had the lowest observed rate of death, while those with readings above 10,000 had the highest death rate.

No firm conclusions were drawn regarding the risk for patients with WBC levels below 3,500.

However, the authors observed that death risk varied even within the normal WBC count range. Those with a high-normal WBC count of 6,000 to 10,000 had a 30 percent to 40 percent higher risk of death than patients with a low-normal WBC count of 3,500 to 6,000, the researchers said.

Ruggiero's team also calculated that for every additional 1,000 cells above the lowest end of the normal range (3,500), a patient's risk of death rose by just over 10 percent.

WBC counts, especially for a type of cell called neutrophils, rose progressively in the years before death, with significant bumps upward observed as early as five years prior to the end of a patient's life. In contrast, WBC counts remained relatively stable among people who survived.

People who died were also more likely to have smoked, to have been less physically active, and to have had worse cardiovascular health.

Death as a result of cardiovascular disease, especially, rose along with increasing WBC counts. WBC counts showed little connection to deaths by cancer.

Overall, white blood cell counts fell for both men and women over the nearly 45-year study period. A host of societal and lifestyle changes could explain the drop, the researchers said, including improvements in diet and exercise habits and the steady drop in smoking and drinking. Environmental changes, such as improved sanitary conditions and less frequent exposure to infectious agents, could also be factors.

The death rate for Americans has also fallen steadily over the past four decades, the authors noted. However, they stressed that they cannot establish any causal link between declines in white blood cell counts and improving life expectancy.

Measuring WBC might prove useful in predicting an individual's health risk, however.

"White blood cell count is usually measured in clinical settings as a marker of infection and hematological diseases," noted Ruggiero. "We suggest that differential WBC counts should be systematically screened and factored (into) the cardiovascular risk profile --and ultimately considered in clinical decisions concerning prescription of preventive interventions."

But Dr. James S. Goodwin, professor of geriatrics and director of the Sealy Center of Aging at the University of Texas Medical Branch in Galveston, isn't convinced.

"The good news is, that as this study shows, a rather substantial decline in WBC counts from around 1960 to 2000," he said. "It goes well with other research showing that there's been a general improvement in health over the last half of the 20th century in the Western world."

But Goodwin believes that, "from the perspective of the individual patient, this observational study suggests nothing specific that should be done differently. It is interesting from a scientific perspective. But for patients, it is not particularly important and has no clinical relevance."

Cushman agreed. "At issue is what the intervention should be if an elevated value is found," she said. "I don't believe that for WBC we know what to do, other than the things we should already be doing, like promoting a heart healthy lifestyle and appropriate screening and prevention for risk factors such as hypertension, diabetes, (and) smoking. This advice would not differ depending on whether the WBC was elevated.

Limitation:

The diagnosis of tuberculous meningoencephalitis (TBM) can be difficult in the absence of microbial isolation, as the clinical presentation is often deceptive and the response to treatment is not as satisfactory as in pyogenic meningitis.

Differentiating TBM from other types of meningitis and CSF infections is not always easy; in the absence of microbial isolation from the CSF the so-called ‘predictive value’ of CSF analysis is still confusing, especially in partially-treated pyogenic meningitis .However, the peripheral WBC count was found to be a valid laboratory test in this study because pyogenic meningitis cases are usually cha-racterized by rapid onset with peripheral neutrophilic leukocytosis while the TBM cases here showed a longer prodromal history and their peripheral WBC counts were normal.

ALL can develop from any lymphoid cell blocked at a particular stage of development, including primitive cells with multilineage potential. In contrast to acute myeloid leukemic cells, which can be readily identified in most instances by the presence of Auer rods, myeloperoxidase, or monocyte-associated esterases, leukemic lymphoblasts lack specific morphologic or cytochemical features, so that the diagnosis of ALL depends on immunophenotyping. Although monoclonal antibodies against 166 different cluster-of-differentiation (CD) molecules on human leukocytes are available, only a few of these molecules are truly lineage-specific. For this reason a panel of antibodies is needed to establish the diagnosis and to distinguish among the immunologic subclasses.

The effect of nucleated erythrocytes and blood megakaryocytes on the apparent WBC count varies with the system used for analysis. Each laboratory should evaluate its system(s) and develop appropriate detection and correction procedures. This is important to prevent reporting a falsely high WBC concentration. With some automated CBC instruments, nucleated erythrocytes or megakaryocytes may present themselves histographically or cytographically, and this can serve as an indicator for careful stained blood film inspection. The laboratory must establish if its particular instrument(s) includes some or all nucleated non leukocytes in its apparent WBC "count".