Hello again.

 

My query about 'whether lactates need to be fasting' has not proved as controversial as 'inappropriate (c..p) use of tumour markers' or even 'order of draw'. I have only two replies so far, but thanks for those. They are authoritative and I will share them. The answer is: no, lactates don't need to be fasting.

 

We specify measurements of lactate as fasting or post-prandial, and  venous, arterial or capillary. The metabolist here is fond of post-prandial capillary/ pre-prandial (+/-fasting) capillary ratios to help recognise mitochondrial disease (value>1 suggestive of disease). We offer the same reference range and find a good deal of overlap although generally there is very little difference between fasting and post-prandial lactate in the absence of mitochondrial disease or primary pyruvate metabolism abnormalities. I can't cite a publication.

 

The French are particularly good at getting samples from indwelling catheters overnight for Lactate and Pyruvate measurements. They use the ratio in differential diagnosis of mitochondrial, TCA and pyruvate metabolic disorders.

The rest of us use what we can get, but remembering any venous stasis will result in a forearm ischaemic test !

There is a role for fasting and post OGTT lactates as part of a profile.

If however question is to rule out a raised lactate, a number of random samples suffices.

 

Regards

Steve