Blood lactate/pyruvate ratio
The normal lactate (0.8 to 2.2 mmol/L) to pyruvate (0.04 to 0.01 mmol/L) blood concentration ratio is less than 25 (lactate 25: pyruvate 1). The lactate/pyruvate ratio depends on the state of tissue oxygenation (lactate = pyruvate multiplied by the state of tissue oxygenation [x]).

The state of tissue oxygenation x depends on the amount of NADH2 and NAD in the cytosol (NADH2/NAD). So a metabolic disorder associated with lactic acidosis and a high number in x will have a high serum lactate level despite low serum pyruvate levels (increased lactate/pyruvate ratio [lactate >35: pyruvate 1]);

whereas diseases with lactic acidosis and a lower x will have a high serum lactate level at the expense of a high pyruvate level (low lactate/pyruvate level [lactate <25: pyruvate 1])