Kidney Stones

Story

Connected to · 6

synergy · 2

Calcium
Counterintuitively, more calcium in the diet goes with fewer calcium-oxalate stones. In the gut, calcium binds oxalate and both leave in the stool, so less oxalate is absorbed into the blood and ends up in the urine. In Curhan 1993's cohort of men, those in the top fifth of dietary calcium had about 0.56 times the stone risk of the bottom fifth (an association). A calcium supplement taken alone, away from meals, cannot do this binding, and Curhan 1997 found it linked with a slightly higher stone risk in women. What matters is calcium that comes with food.
Hypertension
One way of eating does two jobs: the DASH diet lowered blood pressure in randomized trials, and in three large cohorts, people whose diets were closest to DASH had a 40–45% lower risk of kidney stones (an observed association). The citrate and potassium from fruit and vegetables may be part of why it means fewer stones.

regulates · 4

Kidney
Most kidney stones are calcium oxalate; others are uric acid, calcium phosphate, infection-related struvite and cystine stones. Low urine volume is one of the most important risks, and the oxalate, calcium, citrate, acidity and purines in urine all play a part. Changing diet is the first line of prevention; people with recurrent stones, stones on both sides or a family history need a full metabolic evaluation.
Gout & Hyperuricemia
Uric acid stones are one type of kidney stone, and people with gout are clearly more likely to form them than others; acidic urine and high uric acid are the common ground of both. Urate-lowering drugs such as allopurinol and febuxostat are used both to treat gout and to prevent uric acid stones.
Vitamin C
Part of a large dose of vitamin C is turned into oxalate in the body, raising urinary oxalate, and the risk of calcium-oxalate stones may rise with it. Thomas 2013 found that Swedish men who regularly took vitamin C supplements had a higher risk of kidney stones (an observational study). People who have had kidney stones should not take high-dose vitamin C supplements on their own; ask a doctor first.
Hyperuricemia
Uric acid stones make up only a small share of kidney stones and behave differently from common calcium oxalate stones: they crystallize when urine pH is below 5.5 and barely show up on a plain X-ray. So in someone with flank pain and blood in the urine but a normal X-ray, think of them; a CT scan shows them clearly.

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4 main types

EVIDENCEREVIEW 1

READ THE ORIGINAL

A kidney stone is a small stone that forms as minerals in urine slowly crystallize. It sits quietly in the kidney until it drops into the narrow ureter, the tube to the bladder, and gets stuck on its way down. That causes waves of severe pain called colic, which is why stones are one of the most common urological emergencies. Heat and sweating concentrate the urine, so stones form more easily, and they are clearly more common in hot, humid parts of China such as Guangdong and Fujian.

Start with the most counterintuitive line: to prevent the most common kind, calcium-oxalate stones, you should eat enough calcium. In the gut, calcium holds on to oxalate and both leave in the stool, so the oxalate never reaches the urine.

Different minerals need different prevention, so a doctor's first job is usually to find out which kind you have:

Calcium oxalate is the most common, about 70%.Uric acid stones are about 10–15%. They form in people whose urine runs acidic and share a root with gout.Calcium phosphate stones are about 5–10% and form when urine runs alkaline.Struvite (magnesium ammonium phosphate) stones are about 5–10%. Repeated urinary infections cause them; they grow fast and damage the kidney.
What wears people down is how often stones come back. With no prevention at all, about half of people form another stone within five years; serious prevention roughly halves that. If colic comes with a high fever and chills, or you are suddenly passing very little urine or none, go to the emergency department now.

Educational content, not medical advice — consult a clinician.

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Kidney Stones

Story

Connected to · 6

synergy · 2

Calcium
Counterintuitively, more calcium in the diet goes with fewer calcium-oxalate stones. In the gut, calcium binds oxalate and both leave in the stool, so less oxalate is absorbed into the blood and ends up in the urine. In Curhan 1993's cohort of men, those in the top fifth of dietary calcium had about 0.56 times the stone risk of the bottom fifth (an association). A calcium supplement taken alone, away from meals, cannot do this binding, and Curhan 1997 found it linked with a slightly higher stone risk in women. What matters is calcium that comes with food.
Hypertension
One way of eating does two jobs: the DASH diet lowered blood pressure in randomized trials, and in three large cohorts, people whose diets were closest to DASH had a 40–45% lower risk of kidney stones (an observed association). The citrate and potassium from fruit and vegetables may be part of why it means fewer stones.

regulates · 4

Kidney
Most kidney stones are calcium oxalate; others are uric acid, calcium phosphate, infection-related struvite and cystine stones. Low urine volume is one of the most important risks, and the oxalate, calcium, citrate, acidity and purines in urine all play a part. Changing diet is the first line of prevention; people with recurrent stones, stones on both sides or a family history need a full metabolic evaluation.
Gout & Hyperuricemia
Uric acid stones are one type of kidney stone, and people with gout are clearly more likely to form them than others; acidic urine and high uric acid are the common ground of both. Urate-lowering drugs such as allopurinol and febuxostat are used both to treat gout and to prevent uric acid stones.
Vitamin C
Part of a large dose of vitamin C is turned into oxalate in the body, raising urinary oxalate, and the risk of calcium-oxalate stones may rise with it. Thomas 2013 found that Swedish men who regularly took vitamin C supplements had a higher risk of kidney stones (an observational study). People who have had kidney stones should not take high-dose vitamin C supplements on their own; ask a doctor first.
Hyperuricemia
Uric acid stones make up only a small share of kidney stones and behave differently from common calcium oxalate stones: they crystallize when urine pH is below 5.5 and barely show up on a plain X-ray. So in someone with flank pain and blood in the urine but a normal X-ray, think of them; a CT scan shows them clearly.

Read full story

Stop 1/5

4 main types

EVIDENCEREVIEW 1

READ THE ORIGINAL

A kidney stone is a small stone that forms as minerals in urine slowly crystallize. It sits quietly in the kidney until it drops into the narrow ureter, the tube to the bladder, and gets stuck on its way down. That causes waves of severe pain called colic, which is why stones are one of the most common urological emergencies. Heat and sweating concentrate the urine, so stones form more easily, and they are clearly more common in hot, humid parts of China such as Guangdong and Fujian.

Start with the most counterintuitive line: to prevent the most common kind, calcium-oxalate stones, you should eat enough calcium. In the gut, calcium holds on to oxalate and both leave in the stool, so the oxalate never reaches the urine.

Different minerals need different prevention, so a doctor's first job is usually to find out which kind you have:

Calcium oxalate is the most common, about 70%.Uric acid stones are about 10–15%. They form in people whose urine runs acidic and share a root with gout.Calcium phosphate stones are about 5–10% and form when urine runs alkaline.Struvite (magnesium ammonium phosphate) stones are about 5–10%. Repeated urinary infections cause them; they grow fast and damage the kidney.
What wears people down is how often stones come back. With no prevention at all, about half of people form another stone within five years; serious prevention roughly halves that. If colic comes with a high fever and chills, or you are suddenly passing very little urine or none, go to the emergency department now.

Educational content, not medical advice — consult a clinician.