Blood is composed of a liquid plasma, in which there are three floating components - red cells, white cells and platelets. In lupus, levels of any or all of these three components can be reduced.
These cells carry a haemoglobin, which is vital for carrying oxygen around the blood; a low level of red blood cells (and therefore low haemoglobin) is called anaemia. In practical terms, there are two main causes of anaemia in lupus: blood loss (iron deficiency anaemia) and haemolysis (damage of the red blood cells).
The two most common causes of iron deficiency anaemia in lupus are (in women) heavy periods, and blood loss from the digestive tract (often due to irritation by medicines, notably the anti-inflammatory drugs used for arthritis).
The signs and symptoms of anaemia are fatigue, breathlessness and pallor of the skin. Confirmation of the iron deficiency diagnosis is usually made by measurements of serum iron levels. Obviously, if blood loss from the stomach or intestine is suspected further investigations such as a gastroscopy may be required.
A less common, though important, cause of anaemia in lupus is haemolytic anaemia. Antibodies directed against red blood cells make them more fragile. Anaemia (which can be sudden and severe) results from the spontaneous breakdown of the red blood cells in the, circulation.
The white blood cells form a vital defence mechanism. The two main types of white cells are lymphocytes (the immune cells) and polymorphs (also called neutrophils), which are the cells responsible for catching and ingesting bacteria.
In lupus, it is almost the rule that the white blood count is on the low side. In most cases this slightly low count appears to cause no clinical problems. Occasionally, however, the total count falls severely, leaving the patient at an increased risk for infections.
Platelets are minute sausage-like particles that play a vital role in blood clotting. In the normal bloodstream they flow freely, but following any damage, such as a cut they clump together to form part of a blood clot to stop the loss of blood.
In lupus, and especially in Hughes syndrome, the antibodies can affect and damage the platelets. The result can be either a fall in platelet numbers or alternatively, abnormal sticking together to form spontaneous thrombosis.
Low platelet counts can lead to bruising and bleeding. This condition is known as thrombocytopenia, and when it occurs by itself and with no other evidence of lupus, it is known as idiopathic thrombocytopenia purpura (ITP).
In summary, all three major component components of the blood - the white cells, the red cells and the platelets - can be affected in lupus. Fortunately, all three deficiencies (cytopenias) generally respond well to treatment.
This article is intended to inform and give insight but not treat, diagnose or replace the advice of a doctor. Always seek medical advice with any questions regarding a medical condition.