Lactic Acidosis
Lactic acidosis is a rare side effect of nucleoside reverse transcriptase inhibitors (NRTIs) used to treat HIV infection. Mild increases in the amount of lactic acid in the blood are common in people taking NRTIs.
Lactic acid is a chemical made when the cells of the body produce energy. When too much lactic acid builds up in the blood, it can harm the cells. Lactic acid builds up in the blood when the mitochondria aren't working right or don't have enough oxygen.
Lactic acid is turned into lactate in the blood. The muscles of the body create lactic acid and lactate during exercise. The lactate is what makes muscles sore after a workout. The liver breaks down the lactate. If thereÕs too much lactate in the blood, the liver can't keep up.
Lactic acidosis can be a life-threatening condition.
Symptoms
Mildly higher levels of lactate in the blood may not cause any symptoms. Common signs of lactic acidosis include:
- Abnormal heart beat
- Having a hard time breathing
- High lactic acid levels in the blood
- Nausea, vomiting and abdominal pain
- Severe weakness of muscles in the legs and arms
- Tingling and pain in the fingers and toes
- Pancreatitis (inflammation of the pancreas)
- Being tired without reason to be
- Weight loss
- Shortness of breath or rapid breathing
- Cold or blue hands and feet
- Tenderness on the right side of the abdomen under the rib cage. This may be a sign of an enlarged liver.
Sometimes the signs of lactic acidosis appear at the same time as other changes in the body. These changes include loss of fat (lipoatrophy) (link to facial wasting) or build up fat such as with buffalo hump.
Causes
Lactic acidosis is caused by damage to the mitochondria. In HIV-infected people, this damage has been linked to nucleoside reverse transcriptase inhibitors (NRTIs) such as Epivir (lamivudine or 3TC), AZT (zidovudine or Retrovir), abacavir (Ziagen), Zerit (stravudine, d4T), Hivid (ddC) and Videx (didanosine, ddl). These drugs interfere with an enzyme the mitochondria need to reproduce. This leaves the body with fewer mitochondria. The drugs may also interfere with how the mitochondria work.
Lactic acidosis can also happen if the liver can't clear the blood of lactate. NRTIs also cause the liver to become fatty. A fatty liver doesn't work well. It canÕt break down the lactate properly.
Risks of developing lactic acidosis are greater in people who are:
- Taking Zerit (stravudine) and Videx (didanosine)
- Overweight
- Women
- In the later stages of HIV and aren't getting enough food
Taking ribavirin (Rebetol) for hepatitis C infection as well as HIV
Prevention
Currently, there aren't any lab tests to find out who is at risk of lactic acidosis. A person on NRTIs should stay alert for the signs of lactic acidosis. If the signs occur, see a doctor right away.
Diagnosis
It is important that a person with symptoms of lactic acidosis see a doctor as quickly as possible. The doctor may order blood tests to check for:
- Blood acid levels
- Electrolyte level
- Lactate levels. (This is difficult to do and rarely done.)
- Liver function. These tests measure how much of the proteins made and used by the liver are in the blood.
The doctor will also do a physical exam. He or she will check for an enlarged liver. A computed tomography (CT) scan or ultrasound of the liver may be ordered.
Treatment
Treatment will depend on how serious the lactic acidosis is. A person with only mildly high lactate levels and no symptoms may not have to make any changes.
In very serious cases, it may be necessary to stop taking NRTIs. This should never be done without discussing it with a doctor.
A person may need to be in the hospital. Fluids may need to be given through a vein in the arm (intravenously). In life-threatening situations, a person may need to use a machine to help him or her breathe.
