https://www.ncbi.nlm.nih.gov/pubmed/28088395

Feldman AG, Sokol RJ, Hardison RM, Alonso EM, Squires RH, Narkewicz MR; Pediatric Acute Liver Failure Study Group. J Pediatr. 2017 Mar;182:217-222.e3

Abstract
OBJECTIVES:
To assess the accuracy of blood lactate and lactate: pyruvate molar ratio (L:P) as a screen for mitochondrial, respiratory chain, or fatty acid oxidation disorders in children with pediatric acute liver failure (PALF); to determine whether serum lactate ≥ 2.5 mmol/L or L:P  ≥ 25 correlated with biochemical variables of clinical severity; and to determine whether lactate or L:P is associated with clinical outcome at 21 days.

STUDY DESIGN:
Retrospective review of demographic, clinical, laboratory, and outcome data for PALF study group participants who had lactate and pyruvate levels collected on the same day.

RESULTS:
Of 986 participants, 110 had lactate and pyruvate levels collected on the same day. Of the 110, the etiology of PALF was a mitochondrial disorder in 8 (7%), indeterminate in 65 (59%), and an alternative diagnosis in 37 (34%). Lactate, pyruvate, and L:P were similar among the 3 etiologic groups. There was no significant association between the initial lactate or L:P and biochemical variables of clinical severity or clinical outcome at 21 days.

CONCLUSIONS:
A serum lactate ≥ 2.5 mmol/L and/or elevated L:P was common in all causes of PALF, not limited to those with a mitochondrial etiology, and did not predict 21-day clinical outcome.