A Whole-Blood Test of NAD+, NADH, and the NAD+/NADH Ratio
NAD+ testing is a laboratory blood test that measures your intracellular NAD+ (nicotinamide adenine dinucleotide) and its reduced partner NADH, then reports the total NAD pool and the NAD+/NADH ratio. Because NAD+ is essential to how cells produce energy, repair DNA, and regulate metabolism, this single panel offers an objective, cellular-level window into your energy and metabolic status. At Longevity Centers of America, NAD+ testing is offered as a physician-ordered service and is interpreted as one part of a comprehensive evaluation rather than as a stand-alone diagnosis. It is most useful for people who want an objective measure of cellular energy capacity to inform a longevity-focused or fatigue-focused workup, rather than a single number to act on in isolation.
What NAD+ Testing Measures
The NAD+ test is run on a whole-blood sample and reports four related values. A review of NAD+ metabolism describes how NAD+ is required for cellular energy production and for the sirtuin enzymes involved in DNA repair and mitochondrial maintenance, which is why each of these values carries meaning.1 The test uses whole blood rather than plasma because NAD largely resides inside cells, and an intracellular measurement better reflects the energy chemistry actually taking place within them.
NAD+
the oxidized form, used to accept electrons and drive energy-producing reactions.
NADH
the reduced form, which carries electrons into the mitochondrial energy pathway.
Total NAD
the combined pool, reflecting overall NAD availability in the cell.
NAD+/NADH ratio
the balance between the two forms, an indicator of cellular redox state and how efficiently cells are turning nutrients into energy.
Measuring both forms matters because they move differently. A study of age-related NAD+ decline reports that NAD+ tends to fall while NADH rises with aging, so the ratio reveals shifts that measuring NAD+ alone would miss,2 and a study of the plasma NAD+ metabolome describes the NAD+/NADH ratio as a biomarker of redox state and bioenergetics.3
Who Should Consider NAD+ Testing
NAD+ testing is not a general-population screen. A physician may recommend it as part of a broader assessment when cellular energy status is in question. It is commonly considered for:
- Unexplained chronic fatigue, low energy, or reduced stress tolerance
- Exercise intolerance or suspected mitochondrial dysfunction
- Post-viral or chronic-fatigue presentations, where cellular energy capacity is a concern
- Metabolic concerns such as insulin resistance, where impaired cellular energetics and metabolic dysregulation reinforce one another8
- Assessment of biological aging, sarcopenia, and frailty, or an interest in objectively tracking NAD depletion and cellular energy status over time
- Settings of high oxidative-stress or chronic-inflammatory burden affecting NAD-dependent pathways
In each case the test adds an objective data point to an evaluation that also examines metabolic, hormonal, nutritional, and inflammatory markers. A review in Signal Transduction and Targeted Therapy describes how mitochondrial dysfunction reduces available cellular energy and raises oxidative stress, the kind of pattern a measured NAD status can help characterize.7 If none of these apply, NAD+ testing is generally not indicated, and a physician can advise whether it adds value in a given situation.
What to Expect
NAD+ testing follows a straightforward process from order to result. Preparation is simple, though you should follow any specific instructions provided with the collection kit, as timing and handling affect accuracy.
Step 1: Physician order
Because this is a laboratory-developed test interpreted in clinical context, it is ordered by a qualified healthcare provider after discussing whether it is appropriate for you.
Step 2: Whole-blood collection
A whole-blood sample is collected, which preserves the intracellular NAD that reflects what is happening inside cells.
Step 3: Laboratory analysis
Because NAD+ and NADH change quickly after collection, the sample follows specific stabilization and transport requirements and is analyzed by a CLIA-certified laboratory using a validated method. This careful handling is part of why the test is performed through a clinical laboratory rather than a consumer mail-in kit.
Step 4: Results
Results are typically available within one to two weeks and report NAD+, NADH, total NAD, and the NAD+/NADH ratio against reference intervals.
Step 5: Physician review
Your provider interprets the values together, in the context of your symptoms, history, and any other testing, and discusses what they mean for you and whether any further evaluation is warranted. Because the values are interpreted together rather than in isolation, this conversation is where the testing becomes genuinely useful.
Understanding Your Results
Results are reported for all four values against established reference intervals, alongside a visual comparison to a reference population. It is worth being clear about what the panel can and cannot tell you: it characterizes your current cellular NAD status and redox balance, but it does not by itself diagnose or rule out any specific disease, nor is it a measure of how long you will live or a guarantee of any particular health outcome. A common misconception, often promoted in consumer marketing, is that more NAD+ is always better, but the evidence does not support that view, which is precisely why measurement and physician interpretation matter rather than simply assuming higher is healthier. Depleted NAD+ is associated with reduced cellular resilience and with fatigue, metabolic, and neurodegenerative patterns described in the research on age-related NAD+ decline.2 At the same time, abnormally elevated NAD is not necessarily beneficial, and a review of redox biology emphasizes that it is the NAD+/NADH balance, not the absolute amount, that reflects healthy bioenergetics.5 A study of NADPH-coupled redox systems likewise stresses maintaining balanced redox pools rather than maximizing any single value.6
For this reason, results are read as a pattern rather than as a number to push as high as possible. Research using an in vivo NAD assay in the human brain found that altered NAD homeostasis and a redox shift accompany normal aging alongside declining mitochondrial function, illustrating why the ratio is tracked over time.4 Where a result might inform a specific therapeutic decision, that decision rests entirely with the treating clinician. Repeat testing over time can be more informative than any single measurement, because the direction of change, whether the NAD+/NADH balance is stable, improving, or declining, often says more than one snapshot. Your provider will explain what your specific pattern means and what, if anything, it suggests for your broader care plan.
Why NAD+ Matters for Cellular Energy
NAD+ sits at the center of cellular energy production. It declines with age and is consumed more rapidly under inflammation and DNA-repair demand, and the NAD+/NADH ratio reflects how efficiently mitochondria are operating; a review of redox imaging describes that ratio as a sensitive indicator of mitochondrial state implicated in conditions including diabetes and cancer.5 Because NAD+ links energy metabolism, repair, and the biology of aging, a measured NAD status provides context that connects to the Metabolic & Cellular Energy System and the Mitochondrial & Longevity Biology System, which explain the physiology behind the numbers.
Seen this way, the test is less about a target value and more about understanding how well your cellular energy systems are currently functioning.
NAD+ Testing at Longevity Centers of America
As a service, NAD+ testing is valued in longevity and integrative medicine because it adds an objective, cellular-level measurement to an assessment that is often otherwise based on symptoms alone. At Longevity Centers of America, the test is ordered and interpreted by a physician as part of a comprehensive, individualized evaluation, with results considered alongside the rest of your clinical picture and, where appropriate, tracked over time. The goal is a more data-informed understanding of your cellular energy status; any conclusions and any decisions that follow are made by the treating physician in the context of the whole person. In practice, NAD+ testing is most valuable when integrated with other metabolic, hormonal, and inflammatory markers, so that a single panel becomes part of a coherent, individualized picture of cellular health rather than an isolated result.
Test status: NAD+ testing is a laboratory-developed test (LDT) performed by a CLIA-certified laboratory. The U.S. Food and Drug Administration has not approved or cleared this test, and FDA clearance is not currently required for this category of clinical laboratory testing. Results are not intended to be used as a sole means for clinical diagnosis or for patient-management decisions, and should be ordered and interpreted by a qualified healthcare provider as part of a comprehensive evaluation.
Frequently Asked Questions About NAD+ Testing
NAD+ testing measures the intracellular levels of NAD+ and NADH in whole blood and calculates the total NAD pool and the NAD+/NADH ratio. Together, these values provide a snapshot of cellular energy status and mitochondrial redox state.
The NAD+/NADH ratio reflects the cellular redox state, an indicator of how efficiently cells convert nutrients into energy. Because NAD+ tends to fall while NADH rises with age and metabolic stress, the ratio often reveals changes that measuring NAD+ alone would miss, which is why both forms are measured.
A physician may recommend NAD+ testing as part of a broader evaluation for unexplained fatigue, exercise intolerance, suspected mitochondrial or metabolic dysfunction, post-viral fatigue, or the assessment of biological aging. It is not a general-population screening test and is interpreted alongside other clinical information.
Yes. While depleted NAD+ is associated with fatigue and metabolic and neurodegenerative patterns, abnormally elevated NAD is not necessarily beneficial and has been associated with metabolic disturbance in the research literature. Healthy bioenergetics reflects a balanced NAD+/NADH ratio rather than the highest possible level, which is one reason measurement and physician interpretation are important.
No. NAD+ testing is a laboratory-developed test that has not been approved or cleared by the FDA, and its results are not intended to be used as a sole means for clinical diagnosis. It provides one measurable data point about cellular energy status that a qualified healthcare provider interprets within a comprehensive evaluation.
If you are interested in understanding your cellular energy and NAD+ status, speaking with a licensed physician about whether NAD+ testing is appropriate for you is an important first step.
This content is for general educational purposes only and does not constitute medical advice, diagnosis, or treatment. It describes physiology and does not reference specific services. Individual circumstances vary. Always consult a licensed physician regarding your health.
References
- Covarrubias AJ, et al. “NAD+ metabolism and its roles in cellular processes during ageing.” Nature Reviews Molecular Cell Biology / NIH PMC, 2023. PMC9917998
- McReynolds MR, et al. “Age-related NAD+ decline.” Experimental Gerontology / NIH PMC, 2020. PMC7442590
- Clement J, et al. “The Plasma NAD+ Metabolome Is Dysregulated in Normal Aging.” Redox Biology / NIH PMC, 2019. PMC6482912
- Zhu XH, et al. “In vivo NAD assay reveals the intracellular NAD contents and redox state in healthy human brain and their age dependences.” PNAS 112(9): 2876–2881, 2015. doi:10.1073/pnas.1417921112
- Xu HN, Li LZ. “Quantitative redox imaging biomarkers for studying tissue metabolic state and its heterogeneity.” Journal of Innovative Optical Health Sciences / NIH PMC, 2014. PMC6905396
- Bradshaw PC. “Cytoplasmic and Mitochondrial NADPH-Coupled Redox Systems in the Regulation of Aging.” Nutrients 11(3): 504, 2019. doi:10.3390/nu11030504
- Various authors. “Mitochondrial dysfunction in metabolic and aging disease.” Signal Transduction and Targeted Therapy 10, 2025. doi:10.1038/s41392-025-02253-4
- Various authors. “Insulin resistance: pathophysiology and mechanisms.” NIH PMC, 2025. PMC11942056