- Erythrocyte Count
- Hct
- Hematocrit
- Hemoglobin
- Hgb
- Packed cell volume
- PCV
- RBC Count
- RBC's
- Red Blood Cells
- Lavender (EDTA) top tube
- 5 mL of whole blood
This section details the Red Blood Cell (RBC) count, the Hemoglobin (Hgb) and Hematocrit (Hct) which are all routine parts of the Complete Blood Count (CBC) test.
Red blood cell count:
RBCs carry oxygen from the lungs to the tissues and return carbon dioxide from the tissues to the lungs.
Hemoglobin:
Is the molecule that transports oxygen and carbon dioxide. Each gram of Hgb can carry 1.34 mL of oxygen per 100 mL of blood. Hgb also serves as an important buffer in the extracellular fluid.
Hematocrit:
Hct is the percent, by volume, of RBCs in whole blood. For example, an Hct of 45% means that when whole blood was centrifuged, 45% of the blood consisted of RBCs.
These tests are indicated for:
- Determination of anemia or polycythemia
- Detection of hematologic disorders involving RBC destruction as in hemolytic anemia
- Determination of the presence of hereditary hematologic abnormalities
- Monitoring the effects of acute or chronic blood loss
- Monitoring hematologic status during pregnancy
- Monitoring fluid imbalances or their treatment
- Monitoring patients with disorders associated with elevated erythrocyte counts
- Monitoring the progression of non-hematologic disorders associated with abnormal erythrocyte counts
- COPD
- Liver disease
- Hypothyroidism
- Adrenal dysfunction
- Bone marrow failure
- Malabsorption syndromes
- Cancer
- Renal disease
- Monitoring response to drugs or chemotherapy and to evaluate undesired reactions to drugs that may cause blood dyscrasias
- Screening upon admission to a health care facility or before surgery
Additional information:
- Euvolemia is necessary for this test to accurately represent total body hematologic status. When the patient is adequately hydrated with no substantial orthostasic vital sign changes; a presumption of euvolemia can be made.
- Hgb/Hct are not reliable measure of hematologic status in patients with acute blood loss, dehydration or immediately following blood transfusion as euvolemia is not present.
- Usually, the Hct parallels the RBC when the cells are of normal size. As the number of normal-sized erythrocytes increases, so does the Hct. However, for the patient with microcytic or macrocytic anemia, this relationship isn't always as consistent.
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
RBC Count
| RBC Count | Conv. (×106/mm3) | SI (×1012/L) |
|---|---|---|
| Newborns | 4.1-6.3 | 4.1-6.3 |
| 1-2 months | 4.0-6.0 | 4.0-6.0 |
| 2-6 months | 3.8-5.4 | 3.8-5.4 |
| 6 months-5 years | 3.5-5.2 | 3.5-5.2 |
| 6-17 years | 3.8-5.3 | 3.8-5.3 |
| Adult males | 4.2-6.0 | 4.2-6.0 |
| Adult females | 3.5-5.5 | 3.5-5.5 |
Hemoglobin
| Hemoglobin | Conv. (g/dL) | SI (g/L) |
|---|---|---|
| Newborns | 15.0-24.5 | 150-245 |
| 1-2 months | 11.0-19.5 | 110-195 |
| 2-6 months | 10.7-17.0 | 107-170 |
| 6 months-5 years | 10.5-14.5 | 105-145 |
| 6-17 years | 11.0-16.0 | 110-160 |
| Adult males | 14-18.0 | 140-180 |
| Adult females | 12-16 | 120-160 |
Hematocrit
| Hematocrit | Conv. (%) | SI (proportion) |
|---|---|---|
| Newborns | 47-68 | 0.47-0.68 |
| 1-2 months | 35-52 | 0.35-0.52 |
| 2-6 months | 30-49 | 0.30-0.49 |
| 6 months-5 years | 29-43 | 0.29-0.43 |
| 6-17 years | 31-43 | 0.31-0.43 |
| Adult males | 42-54 | 0.42-0.54 |
| Adult females | 37-47 | 0.37-0.47 |
Conditions affecting one of the three parameters (RBC's, Hgb, Hct) inevitably affects the other two parameters. This section will address items known to increase the level of these parameters.
Elevated results of RBC's, Hgb or Hct most typically occur with all 3 parameters being increased. This condition is called Polycythemia.
I. Absolute or true polycythemia
- Primary
- Erythremic erythrocytosis (increased RBC production in bone marrow)
- Polycythemia Vera (a myeloproliferative disorder)
- Secondary
- Alveolar hypoventilation (Asthma, COPD, Pneumonia, Tuberculosis)
- Altitude (High)
- Appropriate (Bone marrow response to physiological conditions)
- Cardiopulmonary disorder
- Carbon monoxide exposure; Chronic (e.g. Smoking cigarettes)
- Cerebellar hemangioblastoma
- Erythropoietin producing tumor
- Hepatoma
- Renal tumor or cyst
II. Relative polycythemia (due to decrease in plasma volume)
- Dehydration/Diarrhea/Vomiting
- Gaisböck's syndrome
- Spurious erythrocytosis (due to stressor)
Drugs that may increase RBC's/Hgb/Hct:
- Erythropoietin
- Glucocorticosteroids
Conditions affecting one of the three parameters (RBC's, Hgb, Hct) inevitably affects the other two parameters. This section will address items known to decrease the level of these parameters.
a) Dilutional anemias:
- Administration of IV fluids
- Burns (Severe)
- Edematous states
- Error due to drawing of specimen above an IV line
- Error due to lipemia
- Pregnancy
- Recumbency
b) Hyperproliferative anemias (decreased Hgb or Hct despite an increased production of RBCs):
- Hemolytic:
- Autoimmune hemolysis
- Chemical related
- Drug related (see list below)
- Enzymopathies
- Hemoglobinopathies
- Hemoglobin S (Sickle cell disease)
- Hemoglobin C disease
- Hemoglobin SC
or 
thalassemia- Hypersplenism (Destruction of RBCs)
- Primary membrane defects
- Prosthetic heart valve or other physical cause for hemolysis
- Rheumatic fever
- Subacute bacterial endocarditis
- Transfusion of incompatible blood
- Traumatic or microangiopathic hemolysis
- Hemorrhagic: acute blood loss
c) Hypoproliferative anemias (inadequate production of RBCs):
- Anemia of chronic disease
- Carcinomas
- Chronic infections
- Leukemia
- Liver disease
- Lymphoma / Hodgkin's disease
- Multiple myeloma
- Myeloproliferative disorders
- Renal failure
- Sarcoidosis
- Systemic lupus erythematosus
- Anemia with blood dyscrasias
- Anemia with organ failure
- Anemia related to endocrine disease
- Addison's disease
- Hypothyroidism
- Renal failure (inadequate erythropoietin production)
- Marrow aplasia
- Myeloproliferative diseases
- Myelophthisic anemia
d) Maturation defect anemias:
- Combined: myelodysplastic syndromes
- Cytoplasmic (Hypochromic anemias)
- Iron deficiency
- Nuclear (Megaloblastic anemias)
- Vitamin B12
- Folate deficiency
e) Parasitic infections
- Babesiosis
- Leishmaniasis
- Malaria
Drugs that can decrease RBCs, Hgb, Hct:
The typical mechanism is either diminished marrow production or induction of hemolysis (especially in those with G6PD).
- Acetaminophen
- Aminopyrine
- Aminosalicylic acid
- Amphetamines
- Anticonvulsants
- Antipyrine
- Arsenicals
- Benzene
- Busulfan
- Carbenicillin
- Cephalothin
- Chemotherapeutic agents
- Chlorate
- Chloroquine
- Chlorothiazide
- Chlorpromazine
- Colchicines
- Corticosteroids
- Dapsone
- Dimercaprol
- Diphenhydramine
- Dipyrone
- Glucosulfone
- Glycerin
- Gold
- Hydroflumethiazide
- Indomethacin
- Mephenytoin
- Methyldopa
- Miconazole
- Nalidixic acid
- Neomycin
- Niridazole
- Nitrobenzene
- Nitrofurantoin
- Novobiocin
- Penicillamine
- Penicillin
- Phenacemide
- Phenazopyridine
- Phenothiazines
- Phenylhydrazine
- Pipobroman
- Primaquine
- Probenecid
- Pyrazolones
- Pyrimethamine
- Quinines
- Streptomycin
- Sulfamethizole
- Sulfamethoxypyridine
- Sulfisoxazole
- Suramin
- Thioridazine
- Tolbutamide
- Trimethadione
- Tripelennamine
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- Clancy KB et al. Menstruation does not cause anemia: Endometrial thickness correlates positively with erythrocyte count and hemoglobin concentration in premenopausal women. Am J Hum Biol. 2006 Sep-Oct;18(5):710-3
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- ZimmermannMB et al.Vitamin A supplementation in children with poor vitamin A and iron status increases erythropoietin and hemoglobin concentrations without changing total body iron. Am J Clin Nutr. 2006 Sep;84(3):580-6