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Mitochondrial coenzyme Q10 determination by isotope-dilution liquid chromatography-tandem mass spectrometry.
Clin Chem. 2013 Aug; 59(8):1260-7.CC

Abstract

BACKGROUND

Coenzyme Q10 (CoQ10) is an essential part of the mitochondrial respiratory chain. Unlike most other respiratory chain disorders, CoQ10 deficiency is potentially treatable. We aimed to develop and validate an accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of mitochondrial CoQ10 in clinical samples.

METHODS

We used mitochondria isolated from muscle biopsies of patients (n = 166) suspected to have oxidative phosphorylation deficiency. We also used fibroblast mitochondria from 1 patient with CoQ10 deficiency and 3 healthy individuals. Samples were spiked with nonphysiologic CoQ10-[(2)H6] internal standard, extracted with 1-propanol and with ethanol and hexane (2 mL/5 mL), and CoQ10 quantified by LC-MS/MS. The method and sample stability were validated. A reference interval was established from the patient data.

RESULTS

The method had a limit of quantification of 0.5 nmol/L. The assay range was 0.5-1000 nmol/L and the CVs were 7.5%-8.2%. CoQ10 was stable in concentrated mitochondrial suspensions. In isolated mitochondria, the mean ratio of CoQ10 to citrate synthase (CS) activity (CoQ10/CS) was 1.7 nmol/U (95% CI, 1.6-1.7 nmol/U). We suggest a CoQ10/CS reference interval of 1.1-2.8 nmol/U for both sexes and all ages. The CoQ10/CS ratio was 5-fold decreased in fibroblast mitochondria from a patient with known CoQ10 deficiency due to recessive prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) mutations.

CONCLUSIONS

Normalization of mitochondrial CoQ10 concentration against citrate synthase activity is likely to reflect most accurately the CoQ10 content available for the respiratory chain. Our assay and the established reference range should facilitate the diagnosis of respiratory chain disorders and treatment of patients with CoQ10 deficiency.

Authors+Show Affiliations

HUSLAB, Helsinki University Central Hospital, Helsinki, Finland. outi.itkonen@hus.fiNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Validation Study

Language

eng

PubMed ID

23640978

Citation

Itkonen, Outi, et al. "Mitochondrial Coenzyme Q10 Determination By Isotope-dilution Liquid Chromatography-tandem Mass Spectrometry." Clinical Chemistry, vol. 59, no. 8, 2013, pp. 1260-7.
Itkonen O, Suomalainen A, Turpeinen U. Mitochondrial coenzyme Q10 determination by isotope-dilution liquid chromatography-tandem mass spectrometry. Clin Chem. 2013;59(8):1260-7.
Itkonen, O., Suomalainen, A., & Turpeinen, U. (2013). Mitochondrial coenzyme Q10 determination by isotope-dilution liquid chromatography-tandem mass spectrometry. Clinical Chemistry, 59(8), 1260-7. https://doi.org/10.1373/clinchem.2012.200196
Itkonen O, Suomalainen A, Turpeinen U. Mitochondrial Coenzyme Q10 Determination By Isotope-dilution Liquid Chromatography-tandem Mass Spectrometry. Clin Chem. 2013;59(8):1260-7. PubMed PMID: 23640978.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Mitochondrial coenzyme Q10 determination by isotope-dilution liquid chromatography-tandem mass spectrometry. AU - Itkonen,Outi, AU - Suomalainen,Anu, AU - Turpeinen,Ursula, Y1 - 2013/05/02/ PY - 2013/5/4/entrez PY - 2013/5/4/pubmed PY - 2013/9/26/medline SP - 1260 EP - 7 JF - Clinical chemistry JO - Clin Chem VL - 59 IS - 8 N2 - BACKGROUND: Coenzyme Q10 (CoQ10) is an essential part of the mitochondrial respiratory chain. Unlike most other respiratory chain disorders, CoQ10 deficiency is potentially treatable. We aimed to develop and validate an accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of mitochondrial CoQ10 in clinical samples. METHODS: We used mitochondria isolated from muscle biopsies of patients (n = 166) suspected to have oxidative phosphorylation deficiency. We also used fibroblast mitochondria from 1 patient with CoQ10 deficiency and 3 healthy individuals. Samples were spiked with nonphysiologic CoQ10-[(2)H6] internal standard, extracted with 1-propanol and with ethanol and hexane (2 mL/5 mL), and CoQ10 quantified by LC-MS/MS. The method and sample stability were validated. A reference interval was established from the patient data. RESULTS: The method had a limit of quantification of 0.5 nmol/L. The assay range was 0.5-1000 nmol/L and the CVs were 7.5%-8.2%. CoQ10 was stable in concentrated mitochondrial suspensions. In isolated mitochondria, the mean ratio of CoQ10 to citrate synthase (CS) activity (CoQ10/CS) was 1.7 nmol/U (95% CI, 1.6-1.7 nmol/U). We suggest a CoQ10/CS reference interval of 1.1-2.8 nmol/U for both sexes and all ages. The CoQ10/CS ratio was 5-fold decreased in fibroblast mitochondria from a patient with known CoQ10 deficiency due to recessive prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) mutations. CONCLUSIONS: Normalization of mitochondrial CoQ10 concentration against citrate synthase activity is likely to reflect most accurately the CoQ10 content available for the respiratory chain. Our assay and the established reference range should facilitate the diagnosis of respiratory chain disorders and treatment of patients with CoQ10 deficiency. SN - 1530-8561 UR - https://www.unboundmedicine.com/medline/citation/23640978/Mitochondrial_coenzyme_Q10_determination_by_isotope_dilution_liquid_chromatography_tandem_mass_spectrometry_ L2 - https://academic.oup.com/clinchem/article-lookup/doi/10.1373/clinchem.2012.200196 DB - PRIME DP - Unbound Medicine ER -