Thrombotic microangiopathy in HIV needs urgent treatment

Patients with HIV infection who develop thrombocytopenia or microangiopathic haemolytic anaemia may survive if thrombotic microangiopathy (TMA) is diagnosed soon enough, according to a review. TMA is recognised by thickening of the walls of terminal arterioles and capillaries and by deposits of clear thrombi which eventually block the vessels. Clinical symptoms are easily confused with those of thrombotic thrombocytopenic purpura (TPP) and haemolytic uraemic syndrome (HUS). TMA is increasingly seen with HIV infection—more so with advanced infection and with classic associated diseases like Pneumocystis carinii pneumonia, Kaposi’s sarcoma, and cytomegalovirus colitis—but it can be the first symptom of HIV infection. So patients with TMA should be tested for HIV, the authors say. Patients with HIV-TMA have homosexual behaviour and intravenous drug use as risk factors for their HIV infection.

Many typical features of TMA are seen with AIDS: thrombocytopenia, anaemia, neuropathy, nephropathy, and raised lactate dehydrogenase, so these are not useful indicators. Diagnosing HIV-TMA is difficult and hinges on seeing fragmented red cells in peripheral blood with unexplained thrombocytopenia or microangiopathic haemolytic anaemia. Patients with HIV who develop these symptoms should be tested urgently for TMA.

Daily plasma exchange seems to be the best treatment, until biochemical markers and platelet counts stabilise. However, long term prognosis is poor. Antiretroviral drugs may help, by preventing collateral endothelial damage by HIV, and have been successful in relapsing HIV-TMA. Whether the newer, more effective, antiretroviral agents might improve prognosis is too soon to say.

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