Leaky Gut Syndrome: The Hidden Driver Behind Dozens of Symptoms

Fatigue, bloating, brain fog, stubborn weight, skin problems, food reactions, joint pain — leaky gut can sit underneath almost any chronic complaint. The problem is that you can’t fix what you haven’t measured, and most approaches skip the one step that actually matters: testing.

Dr. Darrell Kilcup, DC, CFMP, IBUM · In practice since 1991 · Functional medicine by phone & video, nationwide

What is leaky gut syndrome?

Leaky gut is a damaged gut lining. Normally the wall of your intestine is selective — it lets nutrients through and keeps everything else inside the gut, where it belongs. When that barrier is damaged, the junctions between cells loosen and things that should stay in the gut — partially digested food, toxins, microbes — slip into the bloodstream. Your immune system reacts to those intruders, and that reaction can show up almost anywhere in the body.

That’s why leaky gut is so easy to miss: it doesn’t look like a gut problem. It looks like fatigue, or eczema, or a thyroid issue, or weight that won’t move. The symptom is wherever the immune reaction lands — not necessarily your stomach. Below is what it can cause, what damages the gut in the first place, and the part most sources skip: how you actually test for it.

Signs of leaky gut — and the conditions it can drive

Almost any chronic condition can be caused or worsened by a leaky gut. Here’s the range — and notice how it crosses every system in the body, in every age group.

This is only a partial list. From mental-health symptoms to asthma, leaky gut deserves to be on the table as a possible root cause — at any age.

What causes leaky gut?

Leaky gut is common because the gut is constantly under attack. Almost anything unhealthy for the gut lining can cause it to leak. The most frequent culprits I see:

How do you test for leaky gut?

Leaky gut is diagnosed with a blood test that measures zonulin — the protein that controls how tightly the junctions in your intestinal wall stay closed. When zonulin is elevated, those junctions are loosening and the barrier is leaking. The test comes back positive only if your gut is actually allowing things into the bloodstream, so it takes the guesswork out of it.

Depending on the result, more testing may follow. If the leak is being driven by an overgrowth of the wrong microbes, a stool analysis identifies exactly what’s there so it can be treated specifically rather than guessed at.

If you’ve researched leaky gut, you’ve seen the crazy stuff — and you’ve noticed most of it never mentions testing at all. The usual advice is “change your diet and add some supplements.” In my opinion, that won’t get it done. Diet and nutrients are a vital part of the plan, but without testing you’re guessing — and you’ll never know whether the gut is actually healed and treatment can stop. Because leaky gut mimics so many other conditions, you cannot identify it from symptoms alone. Testing is how you end the damage instead of chasing it.

Leaky gut and the problems it hides behind

When the gut barrier leaks, the immune reaction often surfaces somewhere else entirely. These are the connections I see most — each one has a deeper page if it sounds like you.

Leaky gut symptoms in women

In women, leaky gut often wears a hormonal disguise. The same gut-driven inflammation that triggers fatigue, brain fog and bloating also disrupts hormone balance — so the symptoms blur together with PMS, perimenopause and “just getting older,” and the gut never gets investigated.

Common patterns I see: stubborn weight that won’t shift, exhaustion that sleep doesn’t fix, new food sensitivities, skin flare-ups, low mood, and cycles that have changed. When several of these show up together and your labs keep coming back “normal,” the gut barrier is worth testing before you accept that this is just how things are now.

How is leaky gut treated?

This is exactly why testing comes first: the very first step is different for almost every patient, because it depends on what’s damaging the gut. A leak driven by a parasite is treated differently than one driven by trauma or medication. Once that root cause is handled, the repair protocol is fairly standard — the classic “5 R” framework:

If you can’t find help where you live, distance isn’t a barrier

Most healthcare providers still aren’t looking at the gut this way. If you want a no-nonsense, scientific approach that tests instead of guesses, I work with patients across the country by phone and video. Start with the new patient form, or call the Phoenix office.

Dr. Darrell Kilcup Functional Medicine & Hyperbaric Center · 7016 N 27th Ave, Phoenix, AZ 85051