Red Blood Cell Count.

The red blood cell count is also known as RBC.

The red blood cells, or erythrocytes as they are often called, make up the greatest number of cells in the blood. Their normal shape is that of a disc, depressed in the middle (biconcave), which increases their surface area. They also do not contain a nucleus so there is more room for the haemoglobin, a protein that binds to oxygen, which it then carries around the body, making it available to all the tissues.

Thus one can say that the main function of the red blood cells is to carry oxygen to the tissues and to transfer carbon dioxide to the lungs.

Sometimes red cells can have different shapes from the one I described above. This does occasionally occur normally but in most cases it is due to a disease of some sort.

So although actual numbers of red cells will give one some information, knowledge of any abnormalities in the size and shape of the cells will add to that and often help in a diagnosis. For instance in so-called "sickle-cell anaemia", erythrocytes become typically sickle-shaped.

Red cells cannot divide. The average life of an erythrocyte is about 120 days. When they come to the end of their life, they are ingested by phagocytic cells in the liver and spleen.

If stats interest you consider this one - around 3 million red blood cells die and are removed by the liver every second!

The red cell count is the number of red blood cells in a specific volume of blood.

Normal range, as always, varies slightly between laboratories and also with age, sex and altitude.

The higher up you go the scarcer the available oxygen becomes and the more red blood cell you need to carry that oxygen. Peruvians living high up in the mountains, at around 18,000 feet, have been found to have as many as 8.3 million cells/µl, almost double the normal number found in us 'low land' dwellers.

Normal range
Varies with altitude.
Male: 4.7 to 6.1 million cells/µl (per microlitre of blood)
Female: 4.2 to 5.4 million cells/µl
Children: 4.6 - 4.8 million cells/µl

What abnormal results mean:-

Decreased red blood cell count:
a) Anaemia - a lack of red blood cells, which can lead to a deficiency in
oxygen-carrying ability. This can be caused by a number of things eg:-
Heavy periods in women.
A diet low in iron (should also see a low Mean Cell Volume)
A diet lacking in vitamin B12, B6 or folic acid (should see a high Mean Cell Volume).
Malnutrition - which results in a lack of the above vitamins and iron.
Internal bleeding, as from an ulcer or a tumour.
Cancers of the blood, such as leukaemia.
Multiple myeloma - cancer originating in bone marrow plasma cells
Infections, such as malaria and AIDS related infections.
Blood loss due to haemorrhage.
Some drugs eg anti-HIV drugs.
Chronic kidney disease

b) Bone marrow failure caused by:-
Radiation, either accidental or from therapy.
Toxins
Tumours
Fibrosis

c) Haemolysis (RBC destruction), caused by:-
Antigen-antibody reactions
Toxins and poisons
Treatments such as hemodialysis or the use of the heart-lung bypass machine.

Increased red blood cells:
a) Polycythemia, incorporating-
Secondary polycythemia - a condition in which the bone marrow makes more red cells than normal. Often due to chronic lung disease or kidney disorders.
Relative polycythemia -there are not really too many red cells, the problem is too little plasma leading to an elevated RBC because the red cells make up more than half the blood.
Primary polycythemia - also called Polycythemia vera. A condition in which there is a long-term increase in red blood cells and other types of cells. The cause is not known.

b) Dehydration - as from diarrhoea or the use of diuretics or fluid loss due to burns.

c) Kidney disease

d) Addison's disease - the adrenal glands produce insufficient amounts of certain important hormones.

e) Chronic hypoxia (lack of oxygen) caused by:-
Chronic obstructive pulmonary disease
Emphysema
Cystic fibrosis
Pickwickian syndrome (obesity hypoventilation syndrome) - the combination of severe obesity and obstructive sleep apnea (periods of ceasing to breath during sleep).
High altitudes
Pulmonary fibrosis - scarring of the lung.
Cor pulmonale - failure of the right side of the heart caused by prolonged high blood pressure in the pulmonary artery and right ventricle of the heart.
Congenital heart disease

f) Tumours:-
Renal cell carcinoma
Hepatocellular carcinoma - a malignant tumour of the liver
Cerebellar haemangioblastoma - tumour of vascular origin.
Post-renal transplantation
Uterine myoma - fibroids in the uterus
Cushing's syndrome - a disease caused by an excess production of cortisol.

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