Pyruvate

The end product of glycolysis – converted by pyruvate dehydrogenase into acetyl-CoA, which enters the citric acid cycle. Raised with mitochondrial dysfunction or thiamine (B1) deficiency.

What pyruvate does in the body

In glycolysis, the cell splits glucose in the cytoplasm in several steps into two molecules of pyruvate; this already yields some ATP and NADH without oxygen. Pyruvate then stands at a fork in the road: in the mitochondria, pyruvate dehydrogenase converts it into acetyl-CoA, which enters the citric acid cycle. This enzyme complex needs vitamin B1 (as thiamine pyrophosphate) as well as lipoic acid, vitamin B2, niacin and pantothenic acid. Alternatively, pyruvate is converted in the cytoplasm into lactate, with the help of biotin into oxaloacetate, which replenishes the citric acid cycle, in the liver back into glucose, or by transfer of an amino group into the amino acid alanine. Which route dominates depends on how much oxygen is available and how well the mitochondria take up and use pyruvate.

Low pyruvate – what happens in the body?

Little pyruvate is formed when glycolysis processes little glucose – for example during fasting or on a very low-carbohydrate diet, when the cells switch more to fatty acids and ketone bodies. The level also stays low when the mitochondria take up and use pyruvate promptly. Because pyruvate is also the starting material for oxaloacetate, a scarce supply over a longer period can replenish the citric acid cycle somewhat less. A low value usually has no significance of its own; it is read together with lactate and the intermediates of the citric acid cycle.

High pyruvate – what happens in the body?

When pyruvate builds up, it is being formed faster than the mitochondria can use it. An important bottleneck is pyruvate dehydrogenase: when vitamin B1 is lacking – for example with a one-sided diet, high alcohol consumption or malnutrition – less pyruvate becomes acetyl-CoA, and lactate usually rises as well. Less acetyl-CoA means less supply for the citric acid cycle and the respiratory chain; nerve and muscle cells in particular, which use a lot of glucose, then receive less ATP. Raised values also occur with disorders of the mitochondria, after intense exertion and after very carbohydrate-rich meals. Rare inherited disorders of pyruvate dehydrogenase usually become apparent in childhood.

The interpretation is given in your report.