What is the difference between rbc and hematocrit

Top of the page. Test Overview A complete blood count CBC gives important information about the kinds and numbers of cells in the blood, especially red blood cells , white blood cells , and platelets. White blood cell types WBC differential. Red blood cell RBC count. Hemoglobin Hgb. Red blood cell indices. Platelet thrombocyte count.

Mean platelet volume MPV. There are many other reasons that a doctor may want this blood test, including to: Find the cause of symptoms such as fatigue, weakness, fever, bruising, or weight loss.

Check for anemia. See how much blood has been lost if there is bleeding. Diagnose polycythemia. Check for an infection. Diagnose diseases of the blood, such as leukemia. Check how the body is dealing with some types of drug or radiation treatment.

Check how abnormal bleeding is affecting the blood cells and counts. Screen for high and low values before a surgery. See if there are too many or too few of certain types of cells. This may help find other conditions. For instance, too many eosinophils may be a sign of an allergy or asthma. How To Prepare In general, there's nothing you have to do before this test, unless your doctor tells you to.

How It Is Done A health professional uses a needle to take a blood sample, usually from the arm. How It Feels When a blood sample is taken, you may feel nothing at all from the needle. Risks There is very little chance of having a problem from this test. Results Normal Each lab has a different range for what's normal. Blood smear results Normal: Blood cells are normal in shape, size, color, and number.

High values Red blood cells RBC. Conditions that cause high RBC values include smoking, exposure to carbon monoxide, long-term lung disease, kidney disease, some cancers, certain forms of heart disease, alcohol use disorder , liver disease, a rare disorder of the bone marrow polycythemia vera , and a rare disorder of hemoglobin that binds oxygen tightly.

Conditions that affect the body's water content can also cause high RBC values. These conditions include dehydration , diarrhea or vomiting, excessive sweating, and the use of diuretics. The lack of fluid in the body makes the RBC volume look high.

Always consult a health care professional before making a decision about your medication or treatment. What does an abnormal test result mean? Factors that can affect the result of the test Upward Staying in high altitude or in an oxygen-poor setting will increase red blood cell production by the bone marrow. From the puberty, the red blood cells count is lower in women because of the menstruations.

What you need to know before the test Before going for blood tests, a procedure or other exam, it is best to always bring a list of all the drugs you take prescription, OTC and natural health products. Share This Article. Find a Pharmacy. Newsletter Signup. Sign up to our monthly newsletter and adopt healthy habits with your pharmacist's health tips and advice! The WBC count can also increase in patients with leukemia, a cancer of the blood.

Thus, doctors use the WBC count to help determine if a patient has an infection or leukemia. When the WBC count is increased, the type of WBC can help differentiate between a bacterial infection, viral infection or leukemia.

Doctors also use the WBC count to monitor various types of illness, since it may decrease in response to therapy during recovery from an illness. When performing a differential, a medical technologist looks at the various cells under a microscope.

A differential provides information about the relative numbers that is, the percentage of each type of WBC. Such information helps the doctor determine whether an illness is caused by a bacteria, a virus, or leukemia. A differential can be used to monitor patients with allergies and to determine how a patient is recovering from an illness or responding to therapy. These cells include promyelocytes, metamyelocytes, blasts, etc. Presence of any of these cells indicates a need for follow-up with your doctor.

Finally, the differential can provide information about the appearance of RBCs, since the cells are visualized under a microscope. The appearance of RBCs helps differentiate the various types of anemia. Platelets are the smallest blood cells. They are an important part of blood clotting. These small cells clump together and form a sticky mass that helps the blood to clot. Blood clots help your body handle injury by stopping or preventing bleeding.

Blood clots can also cause problems, however, when they occur within the blood vessels or the heart; such clots cause a blockage known as thrombosis. MPV is a measurement of the average size of the platelets. A higher MPV roughly indicates better platelet function.

Thus, the MPV can sometimes be helpful in telling apart different disorders. It is possible that oxygen delivery dynamics at the levels of hemoglobin and hematocrit are associated with vascular function.

Thorling et al. Takemoto et al. Chronic hypoxia affects endothelial dysfunction via increases in inflammation and oxidative stress 19 , Several studies showed that Hct significantly correlated with viscosity 21 , Hct is one of the most important factors affecting blood viscosity. In addition, blood viscosity regulates shear stress, which is an inducer of NO production from the endothelium. Martini et al. These findings suggest that a low level of Hct is harmful for vascular function. Some possible mechanisms underlying the association of excessively high Hct with vascular smooth muscle dysfunction are postulated.

Lewis et al. In addition, high blood viscosity caused by high levels of Hct as well as low blood viscosity caused by low levels of Hct induced low tissue tension of oxygen. According to the Hagen-Poiseuille law, blood flow depends on blood viscosity and vessel radius. Total peripheral vascular resistance is specified by blood viscosity and cardiac output. Fowler et al. These findings suggest that high levels of Hct may induce tissue tension of oxygen by high peripheral vascular resistance and low cardiac output.

These findings also suggest that a high level of Hct may be one of the factors of vascular dysfunction. Cortese-Krott et al. In addition, Zhou et al. These findings suggest that RBC function per se plays an important role in the pathogenesis, maintenance, and development of atherosclerosis through the regulation of vascular function, leading to cardiovascular disease and cardiovascular events.

Simply, NID is assessed by brachial artery response to sublingual administration of nitroglycerine. However, we believe that vascular response to exogenous NO reflects vascular smooth muscle function since NO finally acts on vascular smooth muscle cells. Indeed, NID has been widely used as an indicator of vascular smooth muscle function. Several investigators have shown that vascular response to nitric acid including nitroglycerine reflects vascular smooth muscle function in the brachial artery and coronary artery of humans and in the isolated aorta artery of experimental animals 28 , 29 , It has been shown that NID is impaired in patients with multiple cardiovascular risk factors and that it serves as an independent predictor of cardiovascular events 12 , We believe that reduction in vascular smooth muscle response assessed by NID can also be defined vascular smooth muscle dysfunction.

Recently, some trials have shown that patients with type 2 diabetes mellitus who received an inhibitor of sodium-glucose cotransporter 2 in addition to conventional therapy had significantly lower rates of cardiovascular morbidity and mortality than did patients with type 2 diabetes mellitus who received a placebo in addition to conventional therapy 32 , 33 , In addition, Hct level of An increase in the level of Hct up to Lee et al.

In their study, blood viscosity was an independent variable of carotid IMT in multivariate analysis, while Hct was not an independent variable of carotid IMT 5. Kawamoto et al. The roles of Hct, Hb and RBCs in vascular structure need to be confirmed in future in large clinical trials.

In the present study, the groups with high levels of Hct, Hb and RBCs had vascular smooth muscle dysfunction but not abnormal vascular structure. It is well known that alteration of vascular function occurs before changes in vascular structure. Cohort studies have shown that a high Hct level per se was associated with an increased risk of cardiovascular disease 1 , 2 , 3.

Our study has a number of limitations. First, this study is a cross-sectional design. Therefore, we cannot define causal relationships of Hct, Hb and RBCs with vascular dysfunction and abnormal vascular structure.

Further studies are needed to confirm the effects of changes in levels of Hct, Hb and RBCs on vascular function and structure in long-term follow-up periods using a prospective study design. Second, we evaluated the relationships of Hct, Hb and RBCs with vascular function and structure only in men. We had no information on menstrual cycle when measuring vascular function and structure.

Therefore, we excluded women as study subjects. Further studies are needed to confirm the relationships of levels of Hct, Hb and RBCs with vascular function and structure in women including premenopausal women as well as men after adjustment of the menstrual cycle.

The use of criteria for vascular dysfunction is a better way to calculate the odds ratio. However, diagnostic criteria for endothelial dysfunction assessed by FMD and vascular smooth muscle dysfunction assessed by NID have not been established.

Increases in the levels of Hct, Hb and RBCs within normal ranges may decrease the risk of cardiovascular disease. Hct level of Between September and June , a total of men were recruited for measurement of vascular function from subjects who underwent health-screening examinations or who visited the outpatient clinic at Hiroshima University Hospital.

One hundred eighty-six of the men, including 59 patients with infection, 50 patients with advanced cancer, 11 patients with bleeding, 35 patients with end-stage renal disease, 16 patients who had received prednisolone treatment, and 15 patients with hematologic disease, were excluded. Finally, men were enrolled in this study. Hypertension was defined as systolic blood pressure of more than mm Hg or diastolic blood pressure of more than 90 mm Hg in a sitting position, on at least three different occasions.

DM was defined according to the American Diabetes Association or a previous diagnosis of diabetes 37 , Dyslipidemia was defined according to the third report of the National Cholesterol Education Program All methods were carried out in accordance with relevant guidelines and regulations. Written informed consent for participation in the study was obtained from all of the subjects.

All methods were performed in accordance with the relevant guidelines and regulations overseen by the Ethical Committee in Hiroshima University. Subjects fasted the previous night for at least 12 h and the study began at a. A gauge polyethylene catheter was inserted into the left deep antecubital vein to obtain blood samples. The observers were blind to the form of examination Vascular response to reactive hyperemia in the brachial artery was used for assessment of endothelium-dependent FMD.

The response to nitroglycerine was used for assessment of endothelium-independent vasodilation. NID was measured as described previously Additional details are available in the online-only Data Supplement.

Aortic compliance was assessed noninvasively on the basis of Doppler ultrasound measurements of PWV along the descending thoracoabdominal aorta, as previously published and validated Associations between variables were determined by Spearman rank correlation analysis. Cut-off values of Hct, Hb and RBCs were evaluated on the basis of receiver-operating characteristic curve analysis using the Youden index. We performed formal tests of linearity for the relation between Hct and NID.

The R 2 value of the quadratic model of Hct was better than that of the linear model of Hct 0. Thus, the model with Hct as a quadratic function gives a better fit. Peak Hct of