I would like to express my thanks to the head of the Pharmacobiochemical Laboratory of 3rd Medical Department and the head of 3rd Medical Department Medical Faculty, Comenius University in Bratislava, Associated Professor Viliam Mojto, MD, CSc., MPH, MHA for support and space for creative work. I would like to thank my long-term colleagues and co-authors of this monography for their cooperation: PharmDr. Jarmila Kucharská, CSc., who introduced at our workplace a method for the determination of antioxidants, including coenzyme Q10 in patients in the blood, plasma, tissues, platelets; to RNDr. Zuzana Sumbalová, PhD., who introduced a new non-invasive method of determining respiration and mitochondrial bioenergetics in isolated platelets and tissues in patients at our workplace.