Lactate

This test measures the amount of lactate in the blood or, more rarely, in the cerebrospinal fluid. Lactate is the ionic (electrically charged) form of lactic acid. It is produced by muscle cells, red blood cells, brain, and other tissues during anaerobic energy production and is usually present in low levels in the blood. Aerobic energy production occurs in the mitochondria, tiny power stations inside each cell of the body.  The mitochondria use glucose and oxygen to produce ATP (adenosine triphosphate), the body’s primary source of energy.

Whenever cellular oxygen levels decrease and/or the mitochondria are not functioning properly, the body must turn to less efficient anaerobic energy production to metabolize glucose and produce ATP. In this process, the primary byproduct is lactic acid, which can build up faster than the liver can break it down.

When lactic acid levels increase significantly in the blood, the affected person is said to have first hyperlactatemia and then lactic acidosis (LA). The body can often compensate for the effects of hyperlactatemia, but LA can be severe enough to disrupt a person’s acid/base (pH) balance and cause symptoms such as muscular weakness, rapid breathing, nausea, vomiting, sweating, and even coma.

Lactic acidosis is separated into two types: A and B. Type A may be due to inadequate oxygen uptake in the lungs and/or to reduced blood flow resulting in decreased transport of oxygen to the tissues. Type B is caused by conditions that increase the amount of lactate/lactic acid in the blood but are not related to a decreased availability of oxygen.

Below are some examples of type A and type B causes:

Type A Causes

• Shock from blood loss
• Heart attack
• Congestive heart failure
• Pulmonary edema
• Severe anemia

Type B Causes

• Liver disease
• Kidney disease
• Diabetes
• Leukemia
• AIDS
• Glycogen storage diseases (such as glucose-6-phosphatase deficiency)
• Drugs and toxins
• Severe infections – both systemic sepsis and meningitis
• A variety of inherited metabolic and mitochondrial diseases that are forms of muscular dystrophy and affect normal ATP production
• Strenuous exercise

A blood sample is obtained by inserting a needle into a vein in the arm. Sometimes, an arterial sample is collected by inserting a needle into an artery. Occasionally, a sample of cerebrospinal fluid is collected from the spinal column during a procedure called a spinal tap.

In general, no test preparation is needed. In some cases, your doctor may request that you fast and/or rest prior to the collection.