Blood biomarkers for assessment of mitochondrial dysfunction: An expert review

•A tissue biopsy to measure the role of mitochondria in the pathophysiology, is often not available.•We reviewed biomarkers of mitochondrial dysfunction that can be measured in blood or blood cells.•A single blood biomarker with 100% sensitivity and specificity was not found.•We suggest to use a panel of diverse blood biomarkers to identify a role of mitochondrial dysfunction.•Measuring mitochondrial dysfunction may enable selection of patients for therapies targeting mitochondria.