If you have read that CoQ10 levels fall with age, or that statins deplete them, the obvious next question is whether you can simply have your level tested. A plasma assay does exist, and some laboratories will sell you one. Whether the number it returns answers your question is a different matter entirely.
The short version is that “CoQ10 deficiency” in the medical literature refers to something quite specific, and it is not measured the way a vitamin D level is measured. Understanding why is genuinely useful, because it changes what is worth doing instead.
Two Different Things Get Called CoQ10 Deficiency
A review in Frontiers in Bioscience divides CoQ10 deficiency into two types, primary and secondary [1]. Primary deficiencies are described as “relatively rare disorders resulting from mutations in genes directly involved in the CoQ10 biosynthetic pathway.” Secondary deficiencies, by contrast, are called “relatively common,” and the review attributes them to mutations in genes not directly related to the synthetic pathway, to oxidative-stress-induced reduction of CoQ10, and to pharmacological agents such as statins [1].
Those two conditions share a name and very little else. They differ in cause, in who develops them, in how they present, and in how they are identified. Most of the confusion around CoQ10 testing comes from treating them as one thing.
Primary Deficiency Is Rare, Inherited, and Largely a Childhood Diagnosis
A 2012 review in Archives of Neurology examined 149 cases, including the authors own cohort of 76 patients, and associated CoQ10 deficiency with five major clinical phenotypes: encephalomyopathy, severe infantile multisystemic disease, nephropathy, cerebellar ataxia, and isolated myopathy [2]. Its conclusion was that the syndrome “mainly begins in childhood and predominantly manifests as cerebellar ataxia,” and that causative mutations had been identified in only a small proportion of patients [2].
A 2026 review in Biomolecules describes primary CoQ10 deficiencies as rare inherited mitochondrial disorders caused by pathogenic variants in nuclear genes involved in CoQ10 biosynthesis. Presentation ranges from isolated renal or cerebellar disease to severe multisystem disorders, onset spans from the antenatal period to adulthood, and severity varies widely even among patients carrying variants in the same gene [3].
That is a neurological and renal disease picture. It is not the picture of an otherwise well adult who feels tired and wonders whether their CoQ10 might be low.
Secondary Depletion Is the Common Kind, and It Is Usually Inferred Rather Than Measured
Secondary depletion is the version that is actually relevant to most adults, and it is the one this site covers in depth elsewhere: the influence of statin drugs, of other common medications, and of factors beyond medication.
A 2021 paper in Free Radical Biology and Medicine reviewing secondary CoQ deficiency in neurological disorders makes a point that matters here: CoQ “is the only component of the mitochondrial respiratory chain that can be exogenously absorbed.” The same review describes current understanding of how CoQ is distributed within cells and tissues, particularly in brain and skeletal muscle, as an area of open questions and active controversy, and highlights pharmacokinetic and anatomical challenges in getting supplemented CoQ where it is wanted [4].
In everyday practice, secondary depletion is reasoned about from context rather than confirmed by a number. Someone starting a statin has a plausible mechanism for lower CoQ10; that reasoning does not depend on a test result, and a test result would not meaningfully sharpen it.
Why a Blood Test Probably Will Not Answer Your Question
There are three distinct problems, and they stack.
The sample is wrong. The Archives of Neurology review states it plainly: “Coenzyme Q10 measurement in muscle is the gold standard for diagnosis” [2]. Muscle, not blood. Obtaining that sample means a biopsy, which is not something anyone orders out of curiosity.
A number is not a diagnosis. A review in Expert Review of Molecular Diagnostics calls biochemical determination of CoQ “a good tool for the rapid identification of CoQ deficiencies” but adds that it “does not allow the selection of candidate genes for molecular diagnosis.” Because the synthesis pathway is intricate, incompletely understood, and involves a large number of genes, the review concludes that only next-generation sequencing, whether gene panels or whole-exome and whole-genome sequencing, is presently appropriate for molecular diagnosis [5].
Even in selected patients, the assay often does not confirm. A 2016 study in Biological Research quantified CoQ10 by LC-MS/MS in a cohort of 18 patients who presented with CoQ10-dependent deficiency alongside a respiratory chain defect. Decreased CoQ10 levels were found in eight of the 18, or 45 percent [6]. That is a targeted assay run on a group already suspected of having the disorder.
If a measurement confirms fewer than half of the patients most likely to have the condition, a plasma test ordered on general suspicion in a well adult carries very little information in either direction.
What Is Worth Doing Instead
If there are neurological red flags, that is a clinician conversation, not a supplement decision. Identification genuinely matters in the right patient. The Archives of Neurology review notes the condition “frequently responds to treatment” [2], the molecular diagnostics review notes that primary CoQ deficiencies “may respond well to CoQ treatment” [5], and the Biological Research group observes that CoQ10 defect is the only oxidative phosphorylation disorder that can be clinically improved after oral CoQ10 supplementation [6]. Precisely because the stakes are real in that population, the work belongs with a specialist and a sequencing panel rather than a direct-to-consumer blood draw.
If the interest is medication-related depletion, the useful question is about the medication, not the assay. Whether a statin or another drug plausibly lowers CoQ10 is answerable from what is known about the drug itself, which is the subject of the articles linked above.
If the interest is general wellbeing, the real decision is whether a trial of supplementation is worth making, and on what terms. That turns on practical questions the literature can actually speak to, such as what dose the evidence has studied and how the two available forms differ in absorption. Neither of those decisions is improved by a baseline number.
The Honest Summary
Plasma CoQ10 assays exist and can be purchased. What the published literature supports, though, is narrow: muscle is the reference sample [2], a biochemical value cannot by itself establish a molecular diagnosis [5], and the yield of the measurement is modest even among patients already suspected of the disorder [6]. Meanwhile the common form of depletion is inferred from context, chiefly medication use, rather than measured [1].
For a generally healthy adult wondering whether their CoQ10 is low, a test result in either direction is unlikely to change what they should do next. That is an unsatisfying answer, but it is the one the evidence actually supports, and it saves the cost of a test bought in the expectation of a clarity it cannot deliver.
This article is for general information and does not constitute medical advice. Suspected mitochondrial disease, unexplained neurological symptoms, and any decision about prescribed medication should be discussed with a qualified healthcare professional.
References
- Depletion and Supplementation of Coenzyme Q10 in Secondary Deficiency Disorders. Front Biosci (Landmark Ed), 2022
- Heterogeneity of coenzyme Q10 deficiency: patient study and literature review. Arch Neurol, 2012
- Mitochondrial Dysfunctions in Human Primary Coenzyme Q(10) Deficiencies. Biomolecules, 2026
- Secondary coenzyme Q deficiency in neurological disorders. Free Radic Biol Med, 2021
- Molecular diagnosis of coenzyme Q10 deficiency. Expert Rev Mol Diagn, 2015
- Coenzyme Q10 defects may be associated with a deficiency of Q10-independent mitochondrial respiratory chain complexes. Biol Res, 2016
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.