Sugar and metabolism
Lactaat
Lactic acid in the blood; rises when tissues get too little oxygen, but also due to exercise and the blood draw itself.
Everything about this testWhat it measures
Lactate (lactic acid) is formed when cells make energy without enough oxygen. With enough oxygen, muscles and other tissues burn their fuel into carbon dioxide and water; with too little oxygen, lactate is formed. The liver normally clears lactate again quickly. If it builds up, the blood can become acidic. The test measures the amount of lactate in the blood at the moment of the blood draw.
- A lack of oxygen in tissues, for example in shock, a severe infection or heart failure
- Acidification of the blood due to a build-up of lactate, including with the use of metformin
- Rarely: a metabolic disease or a vitamin B1 deficiency
High
The most common cause of a raised value in someone without symptoms is the blood draw itself or exercise just before: a tourniquet left on for a long time, clenching your fist, tense muscles or cycling to the collection point raise lactate. In healthy athletes, lactate falls again quickly after exercise. A raised value in someone who is ill may fit a lack of oxygen in tissues, as in shock, a severe infection, heart failure or severe anemia, and also liver and kidney diseases. Medicines such as metformin and isoniazid and a vitamin B1 deficiency can raise the value. Symptoms that go with a large rise are rapid breathing, nausea, vomiting, muscle weakness and drowsiness.
Low
A low value is the usual result and has no meaning. No diseases or symptoms are known that go with a low lactate.
Preparation
- Do not exercise in the hours before the sample is taken and sit quietly for 15 minutes just before, also if you came by bike. Exercise raises lactate.
If your result is abnormal
With a slightly raised value without symptoms, the GP usually repeats the measurement under good conditions: at rest, without a tourniquet and with fast processing. With a raised value and symptoms, the GP looks at medicines such as metformin, at liver and kidney function and at signs of infection; with severe symptoms, you are referred to hospital straight away.
Reliability
Lactate is a snapshot that depends strongly on how the blood was drawn and processed. The result says the most in someone who is acutely ill, together with a blood gas test, the liver and kidney values and the clinical picture. In people without symptoms, a slightly raised value is usually the result of exercise or the blood draw and says little about health. The level of lactate also does not point to a cause; according to the Dutch Society for Clinical Chemistry (NVKC), the result must always be assessed together with other results and the medical history.
Limitations
- Exercise just before the blood draw, a tourniquet left on for a long time and clenching your fist raise the value; sitting quietly before the blood draw is needed.
- Blood keeps making lactate after it is drawn; the sample must be cooled or processed quickly, and a sample sent by post without a preservative often gives a value that is too high.
- Metformin, isoniazid and excessive alcohol use can raise the value.
- Reference values differ by laboratory and between blood from a vein and from an artery.
How common is this
A raised lactate due to a lack of oxygen mainly occurs in people who are acutely and seriously ill. In healthy people, a slightly raised value due to exercise or the blood draw is much more common. Dutch figures on how often a raised value occurs in people without symptoms are lacking.
Who is this useful for
The result mainly means something in people who are acutely ill, when acidification of the blood is suspected, with the use of metformin with symptoms, and when a metabolic disease is suspected. In people without symptoms, a single value says little, because exercise and the blood draw easily raise the result.
Downsides and risks
- A rise due to exercise or the blood draw can cause unnecessary worry or lead to unnecessary further testing.
- In people using metformin, a falsely raised value can lead to unnecessarily stopping an effective medicine.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results