Published
6 minute read
Written and medically reviewed by Shiwei Han, MD, PhD
Surgeon-scientist and founder of Hairthetics
Published: September 2026 · Last reviewed: September 2026
Most NAD+ products ask you to make an assumption: that the ingredient on the label produces the intended biological response in your body. Hairthetics takes a different approach. We establish a measurable baseline, use a specific oral NAD+ formulation evaluated in a randomized human trial, and reassess the individual response over time.
The goal is not simply to give you another supplement or another laboratory number. It is to answer a more useful question: did this individual show a measurable biological response to this specific intervention?
• The Hairthetics panel measures whole-blood intracellular NAD+, intracellular NADH and the NAD+/NADH ratio.
• Intracellular measurement is especially relevant because NAD+ performs its principal metabolic and signaling functions inside cells.
• Baseline and follow-up testing can show whether an individual’s measured blood-cell NAD+ biology changed after an intervention.
• Hairthetics uses a specific intact oral NAD+ formulation evaluated as a finished product in a randomized, double-blind, placebo-controlled human trial.
The term “NAD+ blood test” can refer to different measurements. Some tests examine NAD+ circulating outside cells in plasma. The Hairthetics panel measures NAD+ and NADH within the cellular component of whole blood, together with the NAD+/NADH ratio.
NAD+ is the oxidized form and NADH is the reduced form of the same coenzyme pair. They continuously interconvert as cells transfer electrons during metabolism. Measuring both values provides more context than reporting intracellular NAD+ alone. The NAD+/NADH ratio adds information about the redox state of the sampled blood-cell compartment.
This is different from measuring plasma NAD+. Published research has found that extracellular NAD+ in plasma can be far less abundant than intracellular NAD+ in blood cells and may represent distinct biology. For that reason, plasma and intracellular measurements should not be treated as interchangeable.
Whole-blood intracellular NAD+ does not directly measure NAD+ in the brain, muscle, liver or every other organ. It does, however, provide an accessible peripheral biomarker that can help show whether an individual’s blood-cell NAD+ system responds to an intervention. It should be interpreted as a response biomarker rather than as a direct measurement of every tissue.
Yes. This is the central reason to test.
A baseline measurement obtained before an intervention can be compared with a follow-up measurement performed under appropriately consistent conditions. This creates a within-person comparison and can show whether whole-blood intracellular NAD+, intracellular NADH or the NAD+/NADH ratio changed.
A measurable change provides objective evidence that the intervention affected its intended biological target in the sampled blood-cell compartment. Combined with the patient’s experience, clinical context and physician evaluation, that information can help guide the ongoing plan.
Measuring response is valuable only if the intervention itself is worth measuring.
Products marketed with NAD+, NR or NMN language can differ in ingredient, formulation, dose, stability and delivery. General research about NAD+ biology does not prove that every finished product produces the same response. Evidence from one formulation should not automatically be transferred to another.
Hairthetics uses a specific intact oral NAD+ formulation that was evaluated as a finished formulation in a randomized, double-blind, placebo-controlled human trial. After five treatment days, whole-blood intracellular NAD+ was 53% higher in the treatment group than in the placebo group at Day 6. Plasma NAD+ did not significantly increase, and the investigators also reported changes in NAD+ metabolites consistent with downstream metabolic utilization.
Read the peer-reviewed study in GeroScience: https://link.springer.com/article/10.1007/s11357-026-02399-1
DOI: https://doi.org/10.1007/s11357-026-02399-1
These findings apply to the formulation studied. That formulation-specific evidence is one of the principal differences between the Hairthetics approach and purchasing a generic NAD+-related product based only on broad ingredient claims.
For a deeper explanation, read “Not All NAD+ Products Are the Same”: https://www.hairthetics.com/blog/not-all-nad-products-are-the-same/
“Patients should not have to rely only on a label, a generic ingredient claim or a subjective impression. I want to know whether the proposed intervention has evidence for the exact formulation being used and whether we have a plan to evaluate the individual response. That is how testing becomes part of precision medicine rather than simply another number.”
— Shiwei Han, MD, PhD
Dr. Han reviews the patient’s health history, current therapies, goals and clinical context.
When appropriate, Hairthetics establishes a baseline for whole-blood intracellular NAD+, intracellular NADH and the NAD+/NADH ratio through a partnered CLIA-certified laboratory. The kit is sent to the patient, the required sample can be collected by a local phlebotomist, and the completed kit is returned to the laboratory.
When clinically appropriate, the patient begins a physician-directed protocol using the specific intact oral NAD+ formulation evaluated in human research.
Follow-up testing can show whether the measured biomarkers changed after the intervention, providing objective information alongside the patient’s experience.
The ongoing strategy can then be considered in the context of the patient’s results, response and goals.
Hairthetics Precision Longevity™ is designed for people who do not want to select an NAD+ product based only on ingredient popularity, generic research or marketing claims. It is for patients who value physician guidance, product-specific human evidence and objective baseline-to-follow-up measurement.
The 90-day program provides a defined starting point for people who remain skeptical and want an opportunity to evaluate their own measurable response. Separate NAD+ testing is also available for people who want to begin with measurement.
You do not have to guess whether an NAD+-directed intervention produced a measurable response. Hairthetics combines whole-blood intracellular NAD+, NADH and NAD+/NADH ratio testing with physician interpretation and a formulation supported by product-specific human evidence.
That combination—measure, intervene and reassess—is the value of the Hairthetics Precision Longevity™ approach.
Explore Hairthetics Precision Longevity™: https://www.hairthetics.com/precision-longevity/
Separate NAD+ testing options begin at $199. Physician-guided Precision Longevity programs begin at $2,999.
This article is for general education and does not provide individualized medical advice. NAD+ testing and supplementation may not be appropriate for everyone. A laboratory result does not diagnose disease, predict lifespan or guarantee a clinical benefit. Medical history, medications and clinical circumstances should be reviewed with a qualified healthcare professional.
