Anaemia is a condition in which there is a lack of red cells in the blood. Red blood cells carry oxygen round the body by binding the oxygen to a protein called haemoglobin. When there is a shortage of red blood cells or of haemoglobin, the lack of oxygen means that muscles cant generate enough energy, so you may feel tired and weak. Exercise may cause breathlessness and a pounding heart. Severe anaemia can cause headaches, dizziness, vertigo and even heart failure. Women can get increased bleeding during menstruation.

Anaemia is associated with HIV disease progression, independently of CD4 cell count and viral load.

Causes

Many things can cause low haemoglobin or red blood cell levels. The commonest cause in HIV-negative people is bleeding; this can also be a factor in HIV-positive people. Common causes of anaemia in people with HIV include infections or cancers of the bone marrow (where red cells are produced), or drugs which suppress the bone marrow as a side-effect.

Bone marrow suppression can be caused by AZT (zidovudine, Retrovir), foscarnet (Foscavir), ganciclovir (Cymevene), co-trimoxazole (Bactrim / Septrin; at the high doses used to treat Pneumocystis pneumonia [PCP], but not at the doses used for PCP prophylaxis) and dapsone. Chemotherapy drugs for cancer can also suppress the bone marrow.

Pre-existing anaemia may be worsened by any of these medications. The use of AZT is problematic in settings where anaemia is common, such as sub-Saharan Africa.

Rarely, infection with B-19 parvovirus causes anaemia. Certain genetic diseases such as sickle-cell anaemia can also be a cause. A lack of iron, vitamin B₁₂, B₆ or folate in the diet can also cause anaemia.

Infection with histoplasmosis, pneumocystosis, leishmaniasis, and tuberculosis have all been associated with anaemia in HIV-positive individuals. In patients with leishmaniasis, polymerase chain reaction (PCR) analysis of either peripheral blood or bone marrow specimens is needed to obtain an accurate diagnosis of anaemia.

Untreated anaemia in HIV disease is associated with an increased risk of death, regardless of the cause of the anaemia, and is most likely to occur in people with CD4 cell counts below 200 cells/mm³, especially those who have been diagnosed with an opportunistic infection. Anaemia is unusual in people with CD4 cell counts above 200 cells/mm³.

Antiretroviral therapy is not associated with an increased risk of anaemia but this condition remains widespread: a study of over 750 people with HIV in Florida found that 30% had anaemia. A study conducted in Seattle found that the prevalence of anaemia among over 2000 HIV-positive people fell from 22% in 1996 to 8% in 2001. A European study has also found that the prevalence of anaemia has fallen in the HAART era.

In the Florida study, risk factors for anaemia included CD4 cell count below 200 cells/mm³, higher HIV viral load, being African-American and being a woman. Although antiretroviral therapy did not increase the risk of anaemia, taking AZT did. Of patients taking antiviral therapy in this study, 43% of those on AZT had anaemia compared with 19% of those on a non-AZT regimen.

What to do

The most important treatment for anaemia is to find the cause and remove it. If the anaemia is caused by drugs, the best treatment is to reduce the dose or stop taking them.

If vitamin or mineral deficiencies are the problem, it may help to take supplements or to increase your intake of appropriate foods (such as red meat for iron). Your doctor can do blood tests for deficiencies. Drugs can also cause deficiencies. For example, co-trimoxazole interferes with folate metabolism.

Severe anaemia may require treatment with blood transfusion. The decision on whether to transfuse will usually be based on the level of symptoms caused by the anaemia, which will itself depend on factors such as how active the individual is.

A normal haemoglobin level is above 13g/dl. Doctors may be more likely to recommend transfusions for people with severely low levels, such as below 8.0g/dl or possibly higher in people with advanced HIV infection. For people with less seriously low levels, doctors may prefer not to offer a transfusion because the bodys own mechanism for correcting blood abnormalities may be able to correct the problem without intervention.

The Seattle study, mentioned above, found that transfusion was associated with a three-fold increased risk of death in HIV patients, even after adjusting for antiretroviral therapy, AIDS status, CD4 cell count, viral load and haemoglobin level. Patients who received an alternative treatment epoetin alfa (Eprex) did not, however, have an increased risk of death.

Other possible treatments include the use supplements of iron, B vitamins or folate if deficiency of these is the cause of the anaemia.

When the problem is due to drugs that interfere with folate metabolism, such as co-trimoxazole, dapsone and pyrimethamine (Daraprim), supplements of folate may not be effective because the drugs will also inhibit the metabolism of the supplements. Instead, folinic acid should be given, as this provides the vitamin precursors in a way that is not hampered by the drugs.