Kidney stones can form at virtually any age, including in premature newborns, though the peak incidence in adults hits around 30 for men and has two peaks for women, at roughly 35 and 55. What surprises most people is that pediatric kidney stone rates have been climbing for decades, and the age at which someone first develops a stone matters more than you might think for long-term health.
Kidney Stones in Newborns and Infants
The youngest kidney stone patients are premature babies in neonatal intensive care units. Nephrocalcinosis, a condition where calcium deposits form in kidney tissue, occurs in preterm neonates as a result of low gestational age and birth weight, often combined with severe respiratory disease and the medications used to treat it.1PubMed Central. Nephrocalcinosis in preterm neonates One of the earliest documented case series described ten premature infants who developed actual kidney stones, with the probable cause being high urinary calcium excretion triggered by furosemide, a diuretic commonly used in the NICU for lung problems.2PubMed. Nephrolithiasis in premature infants These cases are rare, but they establish that there is genuinely no minimum age for stone formation. When the chemistry is wrong, even immature kidneys can produce stones.
In toddlers and young children, kidney stones are uncommon but not unheard of. When they occur this early, the cause is often a metabolic abnormality or a genetic condition rather than the dietary or lifestyle factors that drive stones in adults. Studies of pediatric stone patients have found that metabolic problems like excessive calcium in the urine or excessive oxalate account for the majority of cases, while genetic mutations explain a meaningful share of the rest.3PubMed. Educational review: role of the pediatric nephrologists in the work-up and management of kidney stones The younger the child, the more likely the cause is something identifiable and sometimes inherited rather than simply bad luck.
Why Teenagers Are Getting More Stones
One of the clearest trends in kidney stone research over the past few decades is the rising incidence among adolescents. A 25-year population study found that the overall incidence in children increased about 4% per year, but that increase was driven almost entirely by those aged 12 to 17, in whom rates nearly tripled, rising from 13 per 100,000 person-years in the mid-1980s to 36 per 100,000 by the late 2000s.4PubMed Central. Temporal trends in incidence of kidney stones among children: a 25-year population based study This isn’t just an American phenomenon. An Icelandic study covering a similar time span showed overall pediatric stone incidence rising from about 4 per 100,000 to 11 per 100,000, with the sharpest climb in adolescent girls aged 13 to 17, whose rate quadrupled from roughly 10 to 39 per 100,000.5PubMed. Incidence of kidney stone disease in Icelandic children and adolescents from 1985 to 2013
What’s driving this? Several factors seem to converge in adolescence. Rising rates of obesity and metabolic syndrome in young people appear to play a role. Research in obese adolescents has found that the more features of metabolic syndrome a teen has, the more their urine chemistry shifts toward conditions that favor stone formation, with lower urine pH and higher saturation for calcium oxalate crystals.6The Journal of Pediatrics. Metabolic Syndrome in Obese Adolescents is Associated with Risk for Nephrolithiasis Dietary shifts toward more sodium and processed food, along with chronic low fluid intake, compound these metabolic changes. Hotter average temperatures may also contribute, since heat exposure has been shown to raise stone risk over relatively short periods.7PubMed Central. Climate change and kidney stones
The Genetic Factor in Young Stone Formers
When kidney stones show up in children and young adults, genetic causes deserve more attention than they often receive. Studies using exome sequencing have found that single-gene mutations account for a striking proportion of early-onset stones. In one cohort of patients who formed their first stone before age 25, researchers identified a causative mutation in about 29% of cases. Another study of pediatric patients found a genetic cause in 75% of those tested.8Frontiers in Urology. Monogenic causation of pediatric nephrolithiasis A separate evaluation of children with stones found that exome sequencing identified a pathogenic variant in about 11% of patients, with the most common metabolic abnormalities being excessive urinary calcium (about 35%) and excessive urinary oxalate (about 24%).9PubMed. Metabolic and Genetic Evaluation in Children with Nephrolithiasis
The wide range in those numbers reflects differences in how patients were selected and tested. But the overall message is consistent: the younger someone is when they form their first stone, the more likely it is that an underlying genetic or metabolic problem is responsible, and the more important a thorough workup becomes. In adults who form their first stone in their 40s or 50s, the cause is more often a combination of diet, fluid intake, weight, and general metabolic health. In a child or teenager, you want to look harder for something specific.
Peak Ages in Adulthood
For adults, kidney stones are overwhelmingly a condition of the working-age years. The peak incidence in men is around age 30, while women show a bimodal pattern with peaks at roughly 35 and 55.10BMJ. Kidney stones That second peak in women coincides with menopause, which is not a coincidence. After menopause, changes in how the body handles calcium, including increased intestinal calcium absorption and shifts in how the kidneys process calcium, alter urinary chemistry in ways that favor stone formation.11PubMed Central. Postmenopausal Hormone Use and the Risk of Nephrolithiasis
A large U.S. population study found that only about 4% of kidney stone cases occurred in adolescents, with the vast majority occurring in adults. The annual incidence rates were roughly 36 per 100,000 women and 109 per 100,000 men.12PubMed Central. Impact of diet on renal stone formation So while stones can happen at any age, the 20s through 50s represent the high-risk window when most first episodes occur.
How the Male-Female Gap Shifts With Age
The sex ratio of kidney stones is not static across the lifespan, and the pattern is more interesting than the common wisdom that “men get more stones” suggests. Overall, men do account for the majority of stones, submitting about 58% of analyzed specimens in one large study.13PubMed Central. Stone composition as a function of age and sex But that average hides a reversal at younger ages: among stone formers in their teens, women actually outnumber men, accounting for about 63% of submitted stones. The female majority persists into the 20s (about 62%) before the ratio flips and men take over through middle age.13PubMed Central. Stone composition as a function of age and sex
A systematic review confirmed that among adolescent females, the rate of increase in kidney stone incidence has been the greatest of any demographic group.14PubMed Central. Gender Differences in Kidney Stone Disease (KSD): Findings from a Systematic Review Then, as both sexes age, the gap between men and women narrows again. A UK Biobank analysis of nearly half a million participants found that the male-to-female relative risk declined significantly with advancing age, shrinking by roughly 1% per year.15Scientific Reports. Age-dependent convergence of kidney stone incidence rates between male and female populations By older adulthood, the rates converge considerably.
Why the female predominance in teenagers? The Icelandic data showed the steepest increases specifically in girls aged 13 to 17.5PubMed. Incidence of kidney stone disease in Icelandic children and adolescents from 1985 to 2013 Researchers have speculated about hormonal factors, dietary patterns, and rising obesity rates in adolescent girls, but no single explanation has been definitively established. It’s one of the more puzzling findings in the field, and it runs counter to the general assumption that kidney stones are predominantly a male problem.
How Stone Composition Changes With Age
The type of stone you form tends to depend partly on how old you are. Calcium-based stones, particularly calcium oxalate, are the most common type at nearly every age. But uric acid stones become more prevalent as people get older, and they are more common in men than in women.16PubMed. Type of renal calculi: variation with age and sex This shift happens because urine pH tends to drop with age and with conditions like insulin resistance and type 2 diabetes, which become more common in older populations. Lower urine pH creates a friendlier environment for uric acid crystals to form.
In children, certain rare stone types that are almost unheard of in adults make occasional appearances. Cystine stones, caused by an inherited transport defect, and xanthine stones, caused by enzyme deficiencies, are examples. One pediatric study found small numbers of both, alongside the more typical calcium-based stones.9PubMed. Metabolic and Genetic Evaluation in Children with Nephrolithiasis These rare types are worth knowing about because they require very different management from the standard calcium oxalate stone. A teenager with cystine stones needs lifelong monitoring and a specific treatment plan, not just the general advice to drink more water.
Kidney Stones in Older Adults
People over 65 absolutely still form kidney stones, but the clinical picture looks different. Elderly patients are more likely to present without the classic, severe flank pain that drives younger patients to the emergency room. Instead, their symptoms may be atypical: fever, urinary abnormalities, or even digestive complaints like diarrhea.17PubMed Central. Nephrolithiasis in elderly population; effect of demographic characteristics This matters because atypical presentations lead to delayed diagnosis, and older adults are also more likely to have complicating factors like impaired kidney function, multiple medications, and anatomical changes from aging.
Drug-induced kidney stones are another age-related concern. An analysis of the FDA’s adverse event reporting database found that the 18-to-65 age group accounted for the largest share of drug-related kidney stone reports (about 42%), followed by the 66-to-85 age group (about 17%), with those under 17 representing only about 1.5%.18Frontiers in Pharmacology. Drug-induced kidney stones: a real-world pharmacovigilance study using the FDA adverse event reporting system database The medications most commonly implicated include certain antibiotics, antiviral drugs, and diuretics. Since older adults tend to take more medications, they face a compounding risk: age-related changes in metabolism plus multiple drugs that can each nudge urine chemistry toward stone formation.
Starting Young Means a Higher Lifetime Recurrence Risk
One of the most clinically significant findings about age and kidney stones is that people who form their first stone before age 20 face a substantially higher risk of recurrence over their lifetime compared to those who start later.19Journal of Pediatric Urology. Stone formation in patients less than 20 years of age is associated with higher rates of stone recurrence This is partly about time: a 15-year-old who forms a stone has decades ahead of them in which to form another one. But it’s also about biology. Young first-time stone formers are more likely to have an underlying metabolic or genetic predisposition that doesn’t go away.
A comprehensive meta-analysis of recurrence risk factors confirmed that younger age at first episode is an independent predictor of recurrence, alongside factors like higher body mass index, family history of stones, and certain stone compositions.20PubMed Central. Risk factors for kidney stone disease recurrence: a comprehensive meta-analysis Separate modeling work identified a similar list, with younger age, male sex, higher BMI, and family history all independently raising recurrence odds.21Mayo Clinic Proceedings. Predictors of Symptomatic Kidney Stone Recurrence After the First and Subsequent Episodes
The practical takeaway for young stone formers is that a first episode in childhood or adolescence should be treated as a signal, not a one-off event. A thorough metabolic evaluation and a long-term prevention plan are more important for a 14-year-old with a first stone than for a 55-year-old with the same presentation, precisely because the younger patient has so many more years of risk ahead.
Why Imaging Choices Differ for Kids
When adults show up in an emergency room with suspected kidney stones, a CT scan is typically the fastest and most accurate diagnostic tool. For children, the calculus (no pun intended) is different. Because children are more sensitive to ionizing radiation and because a young stone former is likely to need repeated imaging over many years, many institutions and professional organizations have shifted toward ultrasound as the first-line imaging modality for pediatric kidney stones.22PubMed. Use of Ultrasound in Pediatric Renal Stone Diagnosis and Surgery Ultrasound is less sensitive for very small stones and for stones located in the ureter, but it avoids radiation exposure entirely, which matters when the patient may need imaging every year or two for decades.
This diagnostic difference highlights a broader theme: kidney stones in children and adolescents are not just a scaled-down version of the adult disease. The causes are more often genetic or metabolic, the sex ratio is reversed, the recurrence risk is higher, and the diagnostic approach needs to account for cumulative radiation exposure over a long life. Parents whose child is diagnosed with a kidney stone should expect a more involved workup than an adult would typically receive, including metabolic blood and urine testing and possibly genetic testing, particularly if there is a family history of stones or if the child is very young.
Climate, Diet, and the Shifting Age of Onset
The trend toward younger stone formers is likely to continue, driven by forces that affect whole populations. Rising average temperatures increase dehydration risk, and the relationship between heat exposure and stone formation is well documented.7PubMed Central. Climate change and kidney stones Childhood obesity rates, while stabilizing in some countries, remain historically high in most of the developed world, and the metabolic consequences that promote stone formation, such as insulin resistance and lower urine pH, track closely with excess body weight in teenagers.6The Journal of Pediatrics. Metabolic Syndrome in Obese Adolescents is Associated with Risk for Nephrolithiasis
Dietary patterns also play a role across age groups. High sodium intake concentrates calcium in the urine, high animal protein loads lower urine pH and raise uric acid excretion, and low fluid intake reduces the volume of urine available to keep minerals dissolved. These factors are not unique to any age, but they are particularly relevant for adolescents whose diets may lean heavily on processed food and sweetened beverages while falling short on water. Adults in their 30s and 40s face similar dietary risks compounded by sedentary lifestyles, workplace dehydration, and the metabolic consequences of weight gain over time.
For older adults, the dietary story shifts again. Reduced appetite, medication side effects, and deliberate calcium restriction (sometimes mistakenly adopted to prevent stones) can create mineral imbalances that paradoxically promote stone formation. One of the more persistent misconceptions at any age is that avoiding dietary calcium prevents calcium stones. In reality, adequate calcium intake from food binds oxalate in the gut and reduces the amount that reaches the kidneys. It is low calcium intake combined with high oxalate intake that raises risk for the most common stone type.