Clinical background:
Measurement of lactate and pyruvate is used in the investigation of lactic acidosis and can help with the diagnosis of pyruvate dehydrogenase (PDH) deficiency.
PDH deficiency is suspected when lactate in blood or plasma > 5.0 mmol/L with lactate/pyruvate ratio < 25.
Pyruvate is very unstable in blood or CSF so samples must be taken into a tube containing perchloric acid (PCA) according to the protocol below.
Specimen container paediatric:
Samples must be taken in a tube containing perchloric acid (PCA).
NuTH requests: contact the metabolic lab (or specimen reception out-of-hours) for a tube. Tubes are available on some GNCH wards. They must be stored upright at 4oC.
Ensure patient details are hand-written on the tube. Do not attach a label to the tube.
External laboratories: contact the metabolic laboratory for a sample collection protocol.
Specimen container adult:
Samples must be taken in a tube containing perchloric acid (PCA).
NuTH requests: contact the metabolic lab (or specimen reception out-of-hours) for a tube. Tubes are available on some GNCH wards. They must be stored upright at 4oC.
Ensure patient details are hand-written on the tube. Do not attach a label to the tube.
External laboratories: contact the metabolic laboratory for a sample collection protocol.
Minimum volume paediatric:
0.5 – 1.0 mL
Minimum volume adult:
0.5 – 1.0 mL
Transport requirements:
NuTH requests: put the tube in a plastic bag to keep it dry, place on ice and transport to the Blood Sciences laboratory immediately.
External laboratories: freeze sample on receipt in the laboratory and send frozen to the metabolic laboratory at the RVI.
Reference ranges:
CSF lactate 0 – 1.8 mmol/L
CSF pyruvate 0.04 – 0.15 mmol/L
CSF lactate/pyruvate ratio 0 – 18
Blood lactate 0 – 1.8 mmol/L
Blood pyruvate 0.035 – 0.150 mmol/L
Blood lactate/pyruvate ratio 0 – 18
Results are reported with interpretative comment.