Coenzyme Q10 (CoQ10) is also referred to as ubiquinone because it can be found in almost all eukaryotic cells.1 CoQ10 embedded in the inner mitochondrial membrane is an essential component of the electron transport chain and plays a role in the ATP-producing oxidative phosphorylation.1 CoQ10 is also a powerful lipid-soluble antioxidant protecting cell membranes and lipoproteins.1 CoQ10 is present in the plasma in both the reduced (ubiquinol) and oxidized (ubiquinone) forms.2 The reduced form of CoQ10 is the only endogenously synthesized lipophilic antioxidant and as such, serves to protect biological membranes against oxidation as well as inhibiting the peroxidation of lipoproteins in the circulation.2 Reduced CoQ10 in plasma may also have a role recycling vitamin E (alpha-tocopherol).3
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
CoQ10 deficiency syndromes are quite rare and are clinically and genetically heterogeneous.4 These conditions have been classified into five major clinical phenotypes: 1. encephalomyopathy; 2. severe infantile multisystemic disease; 3. cerebellar ataxia; 4. isolated myopathy; and 5. nephrotic syndrome. In some cases, specific mutations have been identified in genes involved in the biosynthesis of CoQ10 (primary CoQ10 deficiencies) or in genes not directly related to CoQ10 biosynthesis (secondary CoQ10 deficiencies.4 Respiratory chain defects, reactive oxygen species production, and apoptosis are variably characteristics of primary CoQ10 deficiencies.5 Several of these conditions are responsive to CoQ10 administration.6
CoQ10 is endogenously synthesized via the mevalonate pathway, and some is obtained from the diet with meat products being the principal source.2 CoQ10 supplements are available over the counter.2 Due to its lipophilic nature, CoQ10 is transported in lipoprotein particles in the circulation and plasma levels tend to correlate with serum total and LDL-cholesterol.2
Statins lower blood cholesterol levels by inhibiting HMG-CoA reductase, the rate-limiting enzyme in the biosynthesis of cholesterol.2,7 This same enzyme is involved in the biosynthesis of CoQ10 through the mevalonate pathway. Plasma CoQ10 concentrations are reduced in patients receiving statin therapy.2 The magnitude of CoQ10 decline is dose related and can be reversed by discontinuing therapy.2 It has been postulated that the drop in plasma levels may, in part, reflect by the statin-induced reduction in LDL cholesterol containing particles in the blood stream. The reduction in these lipid particles reduces capacity of the plasma to carry the hydrophobic CoQ10 molecules.2 Alternatively, the lower plasma levels may reflect diminished synthesis of CoQ10 as the result of statin inhibition of HMG-CoA.2,7 A number of studies have reported a drop in the CoQ10 to LDL-cholesterol ratio in plasma after statin treatment.2 This supports the conjecture that CoQ10 depletion is caused by diminished production as well as decreased LDL carriers.2
Statins are generally well tolerated. However, their use has been associated with muscle complaints (myopathy) that range from clinically benign myalgia to more serious myositis, and in rare cases, life-threatening rhabdomyolysis. A variety of mechanisms have been proposed to explain statin-induced myopathy with some proposing that the symptoms may be caused by mitochondrial dysfunction resulting from depletion of CoQ10.7 The results of a recent meta-analysis of available randomized controlled trials do not suggest any significant benefit of CoQ10 supplementation in improving statin-induced myopathy.9
CoQ10 supplementation is commonly used in clinical practice in the treatment of patients with chronic heart failure, male infertility, and neurodegenerative disease.1,6,10,11 Recent findings point to a role of CoQ10 in improving endothelial function in cardiovascular disease.6 A meta-analysis of clinical trials found that CoQ10 supplementation significantly reduced diastolic pressure in hypertensive patients.8 Clinical studies are ongoing related to the effectiveness of CoQ10 supplementation in the treatment of a number of neurodegenerative diseases including Parkinson's disease, Huntington's diseases and Friedreich's ataxia.6 CoQ10 has been found to improve sperm count and motility.6 CoQ10 treatment has also been found to be useful in other conditions ranging from decreasing the incidence of preeclampsia in pregnancy to mitigating headache symptoms in adults and children with migraine.6
1. Mancini A, Festa R, Raimonda S, Pontecorvi A, Littarru GP. Hormonal influence on coenzyme Q(10) levels in blood plasma. Int J Mol Sci. 2011;12(12):9216-9225. PubMed 22272129
2. Molyneux SL, Young JM, Florkowski CM, Lever M, George PM. Coenzyme Q10: Is there a clinical role and a case for measurement? Clin Biochem Rev. 2008 May;29(2):71-82. PubMed 18787645
3. Sohal RS. Coenzyme Q and vitamin E interactions. Methods Enzymol. 2004;378:146-151. PubMed 15038964
4. Quinzii CM, Hirano M. Primary and secondary CoQ(10) deficiencies in humans. Biofactors. 2011 Sep-Oct;37(5):361-365. PubMed 21990098
5. Quinzii CM, Hirano M. Coenzyme Q and mitochondrial disease. Dev Disabil Res Rev. 2010;16(2):183-188. PubMed 20818733
6. Littarru GP, Tiano L. Clinical aspects of coenzyme Q10: an update. Nutrition. 2010 Mar;26(3):250-254. PubMed 19932599
7. Mas E, Mori TA. Coenzyme Q(10) and statin myalgia: what is the evidence? Curr Atheroscler Rep. 2010 Nov;12(6):407-413. PubMed 20725809
8. Rosenfeldt FL, Haas SJ, Krum H, et al. Coenzyme Q10 in the treatment of hypertension: a meta-analysis of the clinical trials. J Hum Hypertens. 2007 Apr;21(4):297-306. PubMed 17287847
9. Banach M, Serban C, Sahebkar A, et al. Effects of coenzyme Q10 on statin-induced myopathy: a meta-analysis of randomized controlled trials. Mayo Clin Proc. 2015 Jan;90(1):24-34. PubMed 25440725
10. Zozina VI, Covantev S, Goroshko OA, Krasnykh LM, Kukes VG. Coenzyme Q10 in Cardiovascular and Metabolic Diseases: Current State of the Problem. Curr Cardiol Rev. 2018;14(3):164-174. PubMed 29663894
11. Mortensen SA, Rosenfeldt F, Kumar A, et al. The effect of coenzyme Q10 on morbidity and mortality in chronic heart failure: results from Q-SYMBIO: a randomized double-blind trial. JACC Heart Fail. 2014 Dec;2(6):641-649. PubMed 25282031
Franke AA, Morrison CM, Bakke JL, Custer LJ, Li X, Cooney RV. Coenzyme Q10 in human blood: native levels and determinants of oxidation during processing and storage. Free Radic Biol Med. 2010 Jun 15;48(12):1610-1617. PubMed 20226852
Miles MV, Horn PS, Tang PH, et al. Age-related changes in plasma coenzyme Q10 concentrations and redox state in apparently healthy children and adults. Clin Chim Acta. 2004 Sep;347(1-2):139-144. PubMed 15313151
Tang PH, Miles MV. Measurement of oxidized and reduced coenzyme Q in biological fluids, cells, and tissues: an HPLC-EC method. Methods Mol Biol. 2012;837:149-168. PubMed 22215546
Tang PH, Miles MV, DeGrauw A, Hershey A, Pesce A. HPLC analysis of reduced and oxidized coenzyme Q(10) in human plasma. Clin Chem. 2001 Feb;47(2):256-265. PubMed 11159774
Tang PH, Miles MV, Miles L, et al. Measurement of reduced and oxidized coenzyme Q9 and coenzyme Q10 levels in mouse tissues by HPLC with coulometric detection. Clin Chim Acta. 2004 Mar;341(1-2):173-184. PubMed 14967174
Tang PH, Miles MV, Steele P, et al. Anticoagulant effects on plasma coenzyme Q10 estimated by HPLC with coulometric detection. Clin Chim Acta. 2002 Apr;318(1-2):127-131. PubMed 11880122
