NAD+ vs NADH vs NAD Total: What the Three Numbers on Your Test Mean
Medically reviewed for accuracy. Last updated July 3, 2026.
Short answer: NAD+ and NADH are two forms of the same molecule. NAD+ is the "empty" form that powers repair and metabolism, NADH is the "loaded" form that carries energy from food. NAD Total is simply the two added together. A good NAD test reports all three, because the balance between them tells you more than any single number.
The 30-second answer: NAD+, NADH, and NAD Total defined
If you have ordered an at-home NAD test, or are about to, you have probably noticed the result is not a single figure. It usually lists NAD+, NADH, and NAD Total. Most articles online only compare the first two, because most of them are written to sell a supplement or an IV drip, not to help you read a lab report. Here is the plain-English version of all three:
- NAD+ is the oxidized, or "empty," form. It accepts electrons and acts as fuel for enzymes that handle DNA repair, metabolism, and cellular stress responses.
- NADH is the reduced, or "loaded," form. It carries the electrons pulled out of the food you eat to your mitochondria, where they help make ATP, the cell's energy currency.
- NAD Total is NAD+ plus NADH: the whole pool of the molecule, in both forms, that your cells have to work with.
NAD stands for nicotinamide adenine dinucleotide. NAD+ and NADH are not competitors. They are the same molecule caught at two points in a constant cycle, and your cells convert one into the other billions of times a day.
NAD+ vs NADH: two forms of one molecule
Think of NAD like a rechargeable shuttle bus. In its NAD+ state it is empty and ready to pick up passengers. When it grabs electrons from the breakdown of glucose or fat, it becomes NADH, the loaded bus. NADH drives to the mitochondria, drops the electrons off to help generate ATP, and turns back into empty NAD+, ready for the next trip.
That redox cycle is why the two forms matter for different jobs. NAD+ is the form your longevity-associated enzymes actually need. Sirtuins and PARPs, the proteins involved in DNA repair and cellular housekeeping, consume NAD+ to do their work, according to a comprehensive review of NAD+ metabolism and its roles in cellular processes during ageing published in Nature Reviews Molecular Cell Biology. NADH, by contrast, is mostly about energy transport. So when people talk loosely about "boosting NAD," what they usually care about is keeping enough available NAD+ on hand.
What is NAD Total, and why it is the number most articles skip
NAD Total is the sum of both forms. It answers a different question than either one alone: not "how is my NAD balanced right now," but "how big is my overall NAD pool to begin with." Two people can have a similar NAD+ reading while one has a much larger total pool, which changes how much reserve they have when demand spikes.
NAD Total gets skipped in most consumer content for a simple reason. If an article exists to sell a precursor supplement, the story is cleaner when it is only about "raising NAD+." But if you are reading an actual test result, the total pool is context you need. A single NAD+ value with no total is a bit like a bank balance with no sense of the account's usual range.
Why the NAD+/NADH balance matters more than any single value
In a healthy, well-fueled cell, most of the free pool sits in the NAD+ form, ready to work. That tilt toward NAD+ is what keeps repair enzymes supplied and metabolism responsive. When the balance shifts the other way, with relatively more NADH, it can signal that cells are struggling to hand off electrons efficiently.
This is why a lab that reports NAD+, NADH, and NAD Total gives you more to work with than a single "NAD level." The ratio between the active and loaded forms is a snapshot of how your redox system is running, and the total tells you the size of the tank. Neither number is a diagnosis on its own, and no consumer test should be read that way, but together they are a more honest picture than any one figure marketed as "your NAD score."
Why NAD declines with age, and the honest nuance
Interest in NAD testing took off because NAD availability tends to fall as people get older. Research measuring whole blood NAD+ contents across age groups found lower levels in older adults, and the Nature Reviews review above describes two forces behind the drop: the body makes less NAD+ and burns through more of it.
On the production side, a key salvage-pathway enzyme called NAMPT becomes less active with age, creating a bottleneck. On the consumption side, an enzyme called CD38 rises in many tissues as low-grade inflammation increases, and CD38 chews through NAD+ faster. Both trends push the available pool down.
It is worth being straight about the uncertainty here. A widely cited analysis, Age-Dependent Decline of NAD+: Universal Truth or Confounded Consensus?, argues that the size and consistency of the decline vary by tissue and study, and warns against treating a fixed "half by middle age" figure as settled science. The direction of the trend is well supported. The exact magnitude for any one person is not something a headline can tell you, which is part of why measuring your own baseline is more useful than assuming.
How NAD is measured, and what an at-home test actually does
NAD can be measured in blood. An enzymatic assay of NAD+ in human blood reported a healthy blood NAD+ concentration of roughly 18 micromolar (with a range of about 15 to 23) and described NAD+ as a metabolic marker worth tracking. Because NAD+ and NADH interconvert quickly, careful labs stabilize the sample and measure both forms, then report the total.
Baselines also vary from person to person. A real-world fingerstick blood study mapping NAD+ across age and gender found meaningful differences between individuals, which is the practical case for testing yourself rather than comparing to an average. Your own trend over time is more informative than a single reading against a population number.
At-home NAD tests use a small finger-prick sample you collect and mail back. Turnaround and thoroughness differ by provider. Boomerang Kits is one option here: its NAD Longevity Blueprint reports NAD+, NADH, and NAD Total from a finger-prick sample and is processed in Boomerang's own CLIA-certified laboratory, which returns results in the app within 24 to 48 hours of the lab receiving your kit. Several longevity-focused labs run week-long turnarounds by comparison, so if speed and getting all three numbers matter to you, they are reasonable things to check for whichever brand you choose. For the bigger picture on how home collection compares to a clinic draw, see our guide to NAD test kits and how to measure your NAD+ at home.
What to do with your numbers
Once you have NAD+, NADH, and NAD Total in hand, the useful move is to treat them as a baseline, not a verdict. Note the values, note the date, and if you make a change aimed at NAD, such as a precursor supplement or a shift in sleep, exercise, or alcohol, retest later under similar conditions and compare. Whether precursors like NMN and NR meaningfully move these numbers is still an open question, which we cover in our evidence review of NMN vs NR. Testing before and after is the only way to see what actually happens in your own body rather than in a marketing claim.
Want your own NAD baseline? The NAD Longevity Blueprint reports NAD+, NADH, and NAD Total from a finger-prick sample, processed in Boomerang's own CLIA-certified lab with results in your app in 24 to 48 hours.
Frequently asked questions
Is higher NAD+ always better?
Not necessarily. NAD+ is the form your repair and metabolism enzymes use, so having enough available matters, but the relationship between NAD+, NADH, and the total pool is more informative than chasing one number as high as possible. Read your result as a balance and a baseline, and discuss it with a healthcare provider rather than self-treating to a target.
Can you really test NAD levels at home?
Yes. NAD can be measured from a small finger-prick blood sample that you collect at home and mail to a lab. Quality depends on how the sample is stabilized and whether the lab reports both NAD+ and NADH, since the two forms convert into each other quickly.
What is a normal NAD level?
There is no single universal number. One blood assay study reported healthy NAD+ around 18 micromolar with a range of roughly 15 to 23, but baselines vary by individual, age, and method, and "normal" ranges are still being refined. Your own trend over time is often more useful than comparing to an average.
Does a high NADH reading mean I have low energy?
Not on its own. A relative shift toward NADH can reflect how efficiently cells are handling electrons, but a consumer test is not a diagnosis of fatigue or any condition. If you have persistent low energy, that is a conversation for your doctor, who can consider the full clinical picture.
How often should I retest my NAD?
A common approach is to establish a baseline, then retest a few months later or after you change something you think might affect NAD, keeping conditions similar each time. Testing before and after a change is the only way to see whether it moved your numbers.
This article is for informational purposes only and is not medical advice. Boomerang Kits tests are not intended to diagnose, treat, cure, or prevent any disease. At-home test results should be discussed with a qualified healthcare provider. Always consult your physician before making health decisions.
