Extension Health

Extension Health operates two clinics in Manhattan, a flagship on Seventh Avenue South in the West Village and a second location on East 60th Street in Midtown East. Dr. Jonathann Kuo, a double-board-certified physician with a background spanning interventional orthopedics, mental health, and regenerative medicine, founded the practice after running Hudson Health, an integrative medicine practice he started in 2010 that has treated more than fifty thousand patients, including heads of state, professional athletes, and other public figures. Extension Health narrows that broader practice to a single mission: measure how a person is actually aging, then intervene on what the numbers show rather than on how a patient feels. The clinic sits inside a wave of New York longevity practices that have drawn coverage from the New York Times, the Wall Street Journal, and Vice, all describing a clientele willing to spend heavily on data before they spend on treatment. That earlier practice, still running alongside Extension Health, gives Dr. Kuo a longer track record in the city's private medicine scene than most longevity clinics founded in the past few years can claim.

A new patient's first visit is entirely diagnostic. The baseline package includes a DEXA scan for body composition and bone density, a resting metabolic rate test, and a VO2 max assessment of cardiorespiratory fitness, the same test conditioning coaches use to gauge an athlete's aerobic ceiling. Blood work covers more than 350 biomarkers spanning hormones, lipids, inflammation, and metabolic function, considerably deeper than a standard annual physical panel. Patients who want it can add an early cancer detection screen on top of the baseline diagnostics. None of this happens in a treatment room. It is measurement first, and the clinic is explicit that nothing gets prescribed until the results are back and reviewed.

Where Extension Health distinguishes itself from a standard blood panel is in its biological age testing, offered through three separate methods rather than one. A TruAge test reads DNA methylation at more than 900,000 sites across the genome and estimates aging speed through a proprietary epigenetic algorithm. A SuPAR test measures a blood protein linked to chronic, low-grade inflammation. A third option, run through Generation Lab, analyzes more than 460 aging-related gene markers from a cheek swab, scored across seven body systems and twelve organs. Biological age testing is still a young science. No single one of these methods has been validated well enough to tell one specific person, with certainty, how fast their body is aging, and any biological age number a patient receives here is worth treating as a research-grade estimate rather than a diagnosis.

The clinic structures every patient relationship around a four-part cycle it labels Assess, Results, Treat, and Optimize. Assess is the diagnostic package described above. Results is a follow-up session, included in the cost of testing, where a member of the care team walks the patient through what the data shows and what it might mean for a treatment plan. Treat is where a longevity specialist designs an actual intervention, which might involve peptide therapy, hyperbaric oxygen sessions, or more involved regenerative treatments depending on membership tier. Optimize is ongoing: repeat testing at set intervals, paired with provider check-ins, so a plan gets revised against fresh blood work rather than left running on numbers from a year earlier.

The Treat phase is where Extension Health moves furthest from a diagnostics-only model. Beyond peptide therapy, the practice offers therapeutic plasma exchange, a process that filters plasma to remove certain circulating proteins, along with extracorporeal blood oxygenation and ozonation, and access to stem cell and exosome treatments for members at the top membership tier. These sit at the frontier in the literal sense: promising in early research, but without the large randomized trials that back cardiovascular medicine or standard cancer screening, and Extension Health's own materials do not claim otherwise. A member paying for these treatments is buying access to therapies still under active study, not a proven longevity protocol with a settled evidence base.

Access runs through three membership tiers rather than a single price list. The Reboot is a two-day intensive for people who want the full diagnostic workup and a same-visit executive health report without an ongoing commitment, priced at fifteen thousand dollars for the two days. The Catalyst, at fifty thousand dollars a year, includes quarterly biomarker testing, monthly coaching, three peptide prescriptions a month, and a fifteen-thousand-dollar credit toward advanced therapeutics. The Superhuman tier, capped at twenty-five members worldwide and priced at a quarter million dollars a year, adds direct oversight from Dr. Kuo and largely unlimited access to the clinic's regenerative treatment menu. There is no walk-in pricing for a single test or a single infusion; everything runs through membership, and a prospective patient starts with a free discovery call rather than a price quote.

Extension Health sits closer to Fountain Life and Human Longevity than to a medical spa: the product is the diagnostic panel and the follow-up protocol, not a menu of walk-in treatments sold on their own. What separates it from those larger, multi-city operators is scale and geography. Extension Health is a single-city practice built around one founding physician's direct involvement, which is central to its pitch at the top membership tier and part of why that tier is capped at twenty-five people rather than opened to anyone who can pay. That is a different model from a retail wellness clinic selling IV drips and cryotherapy to walk-in customers with no diagnostic relationship behind the sale; Extension Health's baseline assumption is that testing comes first and treatment follows from what the testing finds.

This is not a clinic for someone exploring longevity medicine on a modest budget, and it makes no pretense of being one. It suits a Manhattan-based executive or high earner who wants a single physician-led relationship covering diagnostics, treatment, and follow-up, with fresh numbers to check the plan against every few months. The two-day Reboot is the more approachable entry point for someone who wants the full workup without a membership commitment, and it is worth booking if the goal is simply to see, once, what a genuinely comprehensive longevity panel contains. For a patient further along and ready for continuous oversight, the tiered structure here is unusually direct about what serious longevity medicine actually costs, at a level of detail most comparable clinics keep off their websites entirely.