Functional Medicine · Phoenix, AZ
When labs come back "normal" but you still feel terrible
Conventional medicine is built to treat symptoms. Functional medicine is built to find the reason — the actual root cause of why your body isn't working the way it should. Dr. Kilcup has practiced this way for 35+ years. Some patients come in sick. Others come in healthy and want to stay that way. Both are the right fit for this kind of work.
New patients complete a health history form before scheduling — this lets Dr. Kilcup review your case before you come in. In-office and remote consults available.
You've already tried the obvious things
Your doctor says your bloodwork looks fine. Maybe you've seen a specialist or two. You're still exhausted, still foggy, still not right — and nobody can tell you why. This is exactly the kind of case functional medicine is built for.
I don't guess. I don't assume. I test.
One of the most common patterns I see: a patient with years of unresolved symptoms whose GP ran a basic panel — CBC, metabolic, maybe TSH — and called it normal. That panel was never designed to find what's wrong with a chronically ill patient. It was designed to rule out acute disease.
Functional medicine uses a different standard. Functional lab ranges are narrower than conventional reference ranges. A TSH of 3.5 may clear a standard lab's cutoff and still represent a clinically significant thyroid problem. The same is true for ferritin, B12, cortisol, and dozens of other markers. I find what the standard workup missed — not by guessing, but by testing the right things and reading them correctly.
- TSH only (misses T3 conversion)
- Standard CBC & metabolic panel
- Total cholesterol
- Fasting glucose
- Results read against wide reference ranges
- Full thyroid panel: TSH, Free T3, Free T4, reverse T3, antibodies
- Cortisol curve (4-point saliva)
- Advanced lipid fractionation
- Organic acids, micronutrients, inflammatory markers
- Results read against functional optimal ranges
What functional medicine actually means here
The term gets used loosely. Here's what it means in Dr. Kilcup's practice specifically.
Root cause, not symptom coverage
Conventional medicine treats symptoms. Naturopathic medicine often does the same — just without drugs. Only functional medicine is structured around finding and eliminating the upstream driver: the inflammatory trigger, the hormonal imbalance, the deficiency, the toxin.
One of Phoenix's first CFMPs
Dr. Kilcup began FM training in 2013 when the field was new and graduated from Functional Medicine University in 2015 — among the earliest credentialed practitioners in the Phoenix area. That's a decade of clinical application, not a recent certification.
35+ years of clinical pattern recognition
In practice since 1991. Certifications matter. But the ability to recognize what you're looking at comes from decades of seeing patients. No amount of coursework substitutes for that.
A real intake — not 8 minutes
New patient workups begin with a full health history review before you arrive. Your first appointment is a clinical conversation, not an administrative intake. Dr. Kilcup has already read your case before you walk in.
Integrated with advanced therapies
When the clinical picture calls for it, Dr. Kilcup can incorporate HBOT or photobiomodulation — tools not available in most FM practices — as part of your protocol. One physician, one coordinated plan.
In-office or remote
Phoenix-area patients are seen in-office at 7016 N 27th Ave. Functional medicine consults are also available by phone or video for patients outside the metro — the lab work and protocol design translate fully to remote care.
When FM and HBOT intersect
Conditions like mold illness, long COVID, Lyme disease, and neurological recovery often involve both metabolic dysfunction and cellular oxygen deficits. For these cases, Dr. Kilcup is one of the few providers in Phoenix who can run a full functional medicine protocol alongside a clinical HBOT program — under one roof, as a coordinated plan.
Learn about HBOT at this practice →Conditions frequently addressed
Functional medicine is defined by the approach, not a specific condition list. If you're not sure whether your situation fits, complete the health history form and Dr. Kilcup will review it.
- Chronic fatigue / ME-CFS
- Hashimoto's thyroiditis
- Hypothyroid (subclinical)
- Adrenal dysfunction
- Estrogen dominance / hormone imbalance
- PCOS
- Type 2 diabetes / metabolic syndrome
- Inflammatory bowel conditions
- SIBO
- Leaky gut / intestinal permeability
- Autoimmune conditions (multiple)
- Rheumatoid arthritis
- Mold illness / CIRS
- Long COVID recovery
- Lyme disease (chronic / post-treatment)
- Fibromyalgia
- Neuropathy
- Anxiety with physiological drivers
- Insomnia / circadian dysfunction
- Cardiovascular risk factors
What patients say
Real outcomes from real patients — in their own words.
I have many things going on with me — hypothyroidism, Hashimoto's disease, and I'm immune compromised. I was told by a gastro doctor that my pancreas was shot and I was taking a drug called Creon. I'm now off of that and my pancreas is fine. When I started going to Dr. Kilcup there was only a handful of items I could even eat — now the list is much longer. My weight was down to 105; I'm now 120. I have had many of these things since I was a teenager and I'm now in my early 70s, so he's chipping away at something I've had for a very long time. He absolutely positively knows what he's doing. And he cares and he listens. I've been to many doctors — gastroenterologists, MDs, naturopaths, endocrinologists. Nobody has helped me like Dr. Kilcup and his team.
From our very first virtual consult — super convenient since we live about an hour away — he took the time to dive deep into her full history, symptoms, and even lifestyle factors we hadn't considered. No rushing, no cookie-cutter plans. After just a few months on his treatment plan, we've seen game-changing improvements: her energy levels are up, the gut pain has nearly vanished, and she even started working full-time — something that was impossible a few months ago. For the first time in years, she's excited about activities she used to love. Dr. Kilcup didn't just treat her — he empowered our whole family with education and tools to support her long-term wellness.
"Dr. Kilcup's thorough testing revealed root causes of my son's medical problems. Conventional doctors did not do any of this testing and only prescribed medications that treat symptoms. We now have hope for my son's healing."
"I have corrected the issues I presented with. I have lost 11 pounds, have more energy, sleep well and no more bloating. Thank you, Dr. Kilcup, for your knowledge, guidance and support throughout my journey."
"He helped me restore my health after being exposed to toxic mold for years. I never received any care or attention to detail from other doctors except with Dr. Kilcup. Anyone seeking a holistic path towards healing should see him."
How to get started
Functional medicine requires more intake than a standard appointment. Here's what the process looks like.
Complete your health history form
New patients begin with a detailed health history — symptoms, timeline, prior labs, medications, lifestyle. This lets Dr. Kilcup review your case before you arrive, so your first appointment is clinical, not administrative.
Start the Health History Form →Initial consultation with Dr. Kilcup
A full review of your history, symptoms, and any existing labs — in office or by phone/video. Dr. Kilcup will identify gaps in the clinical picture and order additional functional lab work where indicated.
Lab review and protocol design
Once labs return, Dr. Kilcup reviews results through a functional lens and builds a prioritized protocol — diet, supplementation, lifestyle, and any relevant therapies specific to your case.
Ongoing support and adjustment
Functional medicine is iterative. Follow-up appointments track progress, re-test key markers, and refine the protocol as your body responds. Most patients see meaningful change within 6–12 weeks of implementing a complete protocol.
About Dr. Kilcup
Dr. Darrell Kilcup has been in clinical practice since 1991 — 35+ years working directly with patients. He holds a Doctor of Chiropractic and is a Certified Functional Medicine Practitioner (CFMP), having begun FM training in 2013 and graduated from Functional Medicine University in March 2015, making him one of the earliest credentialed FM practitioners in the Phoenix area.
He is one of the few providers in the Phoenix metro who integrates functional medicine with in-office HBOT — which means patients dealing with complex chronic conditions like mold illness, long COVID, or Lyme disease can receive a fully coordinated protocol under one roof, rather than managing multiple providers.
Common questions
Does insurance cover functional medicine?
Do I need a diagnosis to come in?
Can I keep seeing my primary care doctor?
How is this different from seeing a naturopathic doctor?
Do you see patients remotely?
Why do I need to fill out a form before scheduling?
How long does it take to see results?
Are there age restrictions for functional medicine patients?
Start with your health history
If you've been looking for answers that conventional medicine hasn't provided, this is the right next step. Complete your health history — Dr. Kilcup will review it and his team will follow up to schedule your first appointment. In-office or remote.
Dr. Kilcup Functional Medicine Center · 7016 N 27th Ave, Phoenix, AZ 85051