When and why

A lactate test is a type of blood test. It involves measuring the amount of lactate (or lactic acid) present in the blood.

If you are having your lactate measured, your doctor will take a sample of your blood and send it to the lab for analysis.

Lactic levels are normally below 2 mmol/L. All the nucleoside analogue drugs (e.g. AZT, d4T, ddI, ddC, 3TC, abacavir) used in the treatment of HIV infection are associated with elevated lactate levels. D4T and ddI have been specifically linked to the severe and life-threatening condition known as lactic acidosis which occurs when lactate levels are above 10 mmol/L.

Mild symptoms of elevated lactate include fatigue and nausea. These sometimes occur when lactate levels are between 2-5 mmol/L but are more likely when levels are between 5-10 mmol/L. It has been proposed that monitoring may help doctors identify people with raised lactate levels who may be at risk of lactic acidosis.

How it will help

Doctors have not yet established that the lactate test can be used to predict people at risk of lactic acidosis. Consequently, it is not routinely used in HIV medicine at the present time. Research into the application of the lactate test is ongoing.