Kidney stones are tiny, jagged troublemakers that form inside your kidneys and can make grown adults weep.
Right now, more than 1 in 10 Americans will get one at some point, and if you’ve had one before, there’s a 50%+ chance it’ll come back for a sequel.

They’re not just painful — they’re linked to infections, kidney damage, and sky-high healthcare costs.

So what’s fueling them?
Inflammation and poor nutrition are two big suspects. And a strange-sounding metric — the Advanced Lung Cancer Inflammation Index (ALI) — might be the key to predicting who’s at risk.

Wait… Why Is a Lung Cancer Index in a Kidney Stone Study?

ALI isn’t actually just for lung cancer anymore. It’s a quick math formula that combines:

  • BMI (body mass index — your weight relative to height)
  • Albumin (a blood protein that reflects nutrition)
  • Neutrophil-to-Lymphocyte Ratio (NLR) (a marker of inflammation)

Higher ALI = better nutrition + lower inflammation.
Lower ALI = the opposite.

Since inflammation and bad nutrition are both linked to kidney stones, researchers figured: why not see if ALI can flag high-risk people?

The Big Study

Using NHANES, a massive U.S. health survey, researchers crunched the numbers. Here’s the plot twist:

  • In the total population: ALI wasn’t linked to kidney stone risk in a meaningful way.
  • When split by sex: BOOM — in men, higher ALI meant lower risk. In women, nada.

In men, each one-point increase in ALI was linked to a 22.7% lower chance of having kidney stones.

Why the Gender Gap?

Men and women are biologically different when it comes to:

  • Hormones: Estrogen may protect women by calming inflammation.
  • Body composition: Men tend to have higher BMI and albumin, which bumps their ALI score.
  • Immune responses & urine chemistry: Both affect how easily crystals form.

Bottom line: ALI seems to “work” better as a predictor in men.

Why ALI Might Protect Against Stones

The components of ALI each tell part of the story:

  • Low albumin = poor nutrition, more free calcium in urine → more stones.
  • High inflammation (high NLR) = messes with calcium and oxalate metabolism → more crystal formation.
  • Low BMI (especially if it’s due to malnutrition) = fewer reserves to buffer these effects.

A higher ALI means fewer of these bad conditions — so less stone-friendly chemistry in your kidneys.

The Sweet Spot: Overweight, Older, and Healthy

The ALI–stone protection effect was strongest in:

  • Men aged 60–80
  • Overweight (BMI 25–29.9) but not obese
  • No diabetes, hypertension, or heart disease

This might even tie into the so-called “obesity paradox” — in certain groups, carrying a little extra weight (and having better nutrition reserves) can be protective.

Why This Matters

  • ALI is cheap and easy — it’s just math using standard bloodwork and BMI.
  • Could become a screening tool to spot higher-risk patients, especially men.
  • Might guide diet and lifestyle advice to lower stone risk before the pain hits.

The Fine Print

  • This was a cross-sectional study — basically a snapshot in time — so we can’t say ALI causes lower risk.
  • The data relied on self-reported kidney stone history (hello, recall bias).
  • Women might still benefit from high ALI, but this study didn’t prove it.

Takeaway:
A stronger ALI score — meaning better nutrition and lower inflammation — might protect men from kidney stones. Women? Still an open question. But if your BMI, albumin, and inflammation markers are all in a good range, your kidneys might thank you.

Zhou Y, Li X, He Q, Feng Q, Liu Y, Liao B. The advanced lung cancer inflammation index as a predictor of kidney stone risk in men: a cross-sectional analysis. Front Nutr. 2025 Jul 24;12:1568427. doi: 10.3389/fnut.2025.1568427. PMID: 40777182; PMCID: PMC12329308.