Elevated blood lactate in resting conditions correlate with post-exertional malaise severity in patients with Myalgic encephalomyelitis/Chronic fatigue syndrome by Alaa Ghali, Carole Lacout, Maria Ghali, Aline Gury, Anne-Berengere Beucher, Pierre Lozac’h, Christian Lavigne & Geoffrey Urbanski (France) in Nature Scientific Reports vol 9, Article number: 18817 (2019) Published Dec 11, 2019
Elevated blood lactate after moderate exercise was reported in some of patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).
We hypothesised that blood lactate could be also elevated in resting conditions. We aimed investigating the frequency of elevated lactate at rest in ME/CFS patients, and comparing characteristics of ME/CFS patients with and without elevated lactate.
Patients fulfilling international consensus criteria for ME/CFS who attended the internal medicine department of University hospital Angers-France between October 2011 and December 2017 were included retrospectively. All patients were systematically hospitalised for an aetiological workup and overall assessment. We reviewed their medical records for data related to the assessment: clinical characteristics, comorbidities, fatigue features, post-exertional malaise (PEM) severity, and results of 8 lactate measurements at rest. Patients having ≥1 lactate measurement ≥2 mmol/L defined elevated lactate group.
The study included 123 patients. Elevated (n = 55; 44.7%) and normal (n = 68; 55.3%) lactate groups were comparable except for PEM, which was more severe in the elevated lactate group after adjusting for age at disease onset, sex, and comorbidities (OR 2.47, 95% CI: 1.10–5.55).
ME/CFS patients with elevated blood lactate at rest may be at higher risk for more severe PEM. This finding may be of interest in ME/CFS management.
From the conclusion:
At the best of our knowledge, this is the first study that reports elevated blood lactate in resting conditions in a significant proportion of patients with ME/CFS. Patients who showed abnormal elevation of blood lactate at rest displayed more frequent severe PEM than those with normal lactate concentrations.
This finding brings supplementary evidence for mitochondrial dysfunction in ME/CFS patients, and may contribute to a better understanding the illness.
Subtyping ME/CFS patients adds to the growing body of evidence that ME/CFS is heterogeneous, and allows identifying patients with more risk for severe PEM who must adhere more closely to pacing strategies in order to avoid PEM occurrence and prevent disease exacerbation.
Furthermore, our study allowed describing clinical and biological characteristics of a French population with MPE/CFS. Shedding light on these characteristics may improve knowledge and raise awareness of this public health issue.