Reproducibility of the lactate stress test.

Although the lactate stress test has been shown to be a powerful tool to screen for respiratory chain disorders, little is known about the reproducibility of this test. The aim of the present study was thus to look for the reliability of the lactate stress test in disease controls and patients with primary respiratory chain disorders. In 23 patients with respiratory chain disorder, 16 women and 7 men, aged 36-81 years, and 18 disease controls, 5 women and 18 men, aged 37-70 years, the lactate stress test was carried out when respiratory chain disorder was suspected for the first time and at the first follow-up. The sensitivity of the first lactate stress test was 81% and the specificity 72%. The sensitivity of the second lactate stress test was 74% and the specificity 61%. The reproducibility of the lactate stress test was 65% in patients with respiratory chain disorders and 78% in disease controls. In conclusion, this study shows that the sensitivity, specificity, and reproducibility of the lactate stress test is high enough to warrant its application as a reliable, supplementary method to search for respiratory chain disorders.