Women absolutely get kidney stones, and they are getting them at a sharply rising rate. Between 2007 and 2018, the prevalence of kidney stones among women in the United States climbed from about 6.5% to roughly 9.4%, a statistically significant upward trend that was not matched by a similar increase in men.1European Urology Focus. Stone Disease Prevalence and Trends in Kidney Stone Among Adults in the USA: Analyses of National Health and Nutrition Examination Survey 2007–2018 Data While men still develop stones more often overall, the gap is narrowing fast, and several risk factors are unique to female biology, from hormonal shifts around menopause to the physical changes of pregnancy.
The Gender Gap Is Closing
Kidney stones have long been treated as a “man’s problem.” The old clinical rule of thumb put the male-to-female ratio at roughly three to one. That ratio has been shrinking steadily. A systematic review examining national survey data found that the rise in stone prevalence among women was statistically significant over the past decade, while the increase among men was not.2PubMed Central. Gender Differences in Kidney Stone Disease (KSD): Findings from a Systematic Review – Section: Epidemiology of Gender Gap When researchers looked specifically at working-age adults under 50, women were just as likely as men to develop stones. Among adolescent females, the increase in stone rates was the steepest of any demographic group.
Why the shift? Rising rates of obesity, metabolic syndrome, and dietary changes play a role across both sexes, but women may be catching up because those metabolic risk factors overlap with hormonal and reproductive factors that amplify stone risk in ways men do not experience. The rest of this article unpacks each of those pathways.
How Estrogen Protects Against Stones, and What Happens When It Drops
Estrogen appears to be a natural shield against certain types of kidney stones. It influences calcium metabolism in several ways: lowering the amount of calcium in urine by reducing bone breakdown and by improving how the kidneys reabsorb calcium.3The Journal of Urology. Etiological Role of Estrogen Status in Renal Stone Formation Estrogen also helps maintain higher levels of urinary citrate, a substance that binds to calcium and keeps it dissolved in urine rather than letting it crystallize into a stone. Research on postmenopausal women with recurrent stones found that those taking estrogen had roughly double the urinary citrate of those who were not, along with stronger inhibition of crystal clumping.4The Journal of Urology. Estrogen Replacement Increased the Citrate and Calcium Excretion Rates in Postmenopausal Women With Recurrent Urolithiasis
When estrogen levels fall at menopause, these protections weaken. A large prospective study following over 100,000 women for 22 years found that postmenopausal women had about a 27% higher risk of developing a symptomatic kidney stone compared with premenopausal women. The risk was even greater for women who had undergone surgical menopause (such as removal of both ovaries), where the relative risk jumped to about 43% higher.5PubMed Central. Menopause and Risk of Kidney Stones The abruptness of the hormonal drop after surgical menopause likely explains the extra risk compared with the more gradual decline of natural menopause.
A separate systematic review identified menopause itself, a history of multiple pregnancies, and use of female hormones as independent risk factors for stones in women.2PubMed Central. Gender Differences in Kidney Stone Disease (KSD): Findings from a Systematic Review – Section: Epidemiology of Gender Gap So the very transitions that define female reproductive life, puberty, pregnancy, and menopause, all mark periods when stone risk shifts.
Does Hormone Therapy After Menopause Help or Hurt?
You might assume that replacing the lost estrogen would bring back its protective effects. The picture is surprisingly messy. In the large prospective study mentioned above, postmenopausal hormone therapy was not significantly associated with kidney stone risk one way or the other.5PubMed Central. Menopause and Risk of Kidney Stones But a separate analysis from the Women’s Health Initiative hormone therapy trials found that estrogen therapy was actually tied to a modest increase in stone risk, with the rate rising from about 34 to 39 cases per 10,000 person-years. When the analysis was limited to women who stuck with their medication, the risk increase became more pronounced.6PubMed Central. Postmenopausal Hormone Use and the Risk of Nephrolithiasis: Results From the Women’s Health Initiative Hormone Therapy Trials
The contradiction probably reflects the complexity of estrogen’s effects. Estrogen raises urinary citrate (which inhibits stones) but also increases urinary calcium excretion (which can promote them). The net result depends on the dose, the type of estrogen, whether progesterone is included, and the individual woman’s metabolism. For now, hormone therapy should not be started or stopped based on stone risk alone, but if you are on it and have a history of stones, the topic is worth raising with your doctor.
Kidney Stones During Pregnancy
Pregnancy creates a near-perfect setup for stone formation. Kidney blood flow and filtration rate both increase by more than 50%, which pushes more calcium, uric acid, sodium, and oxalate into the urine.7PubMed Central. Renal stones in pregnancy At the same time, the growing uterus compresses the ureters (the tubes connecting each kidney to the bladder), and elevated progesterone slows the muscular contractions that normally push urine downward. Up to 90% of pregnancies show some degree of hydronephrosis, a backup of urine in the kidney, on imaging.8PubMed Central. Risk of Symptomatic Kidney Stones During and After Pregnancy Stagnant urine means stone-forming minerals stay in contact with the kidney lining longer, raising the odds of crystallization.
In fact, urine chemistry during normal pregnancy can look as alarming as it does in people who form stones chronically. Pregnant women excrete more calcium per day than the average stone patient, and their urine reaches supersaturation levels for calcium oxalate that rival those of women with established stone disease.9Kidney International. Gestational hypercalciuria causes pathological urine calcium oxalate supersaturations The reason most pregnant women do not actually form stones is still debated. Protective factors like slightly higher urine pH and residual inhibitors of crystal growth appear to keep the balance tipped just barely in the right direction.
When stones do develop during pregnancy, the stakes are higher. A meta-analysis covering 4.7 million pregnancies found that kidney stones during pregnancy were significantly associated with preeclampsia, urinary tract infections, low birth weight, preterm labor, and a higher rate of cesarean deliveries.10PubMed. Incidence of kidney stones in pregnancy and associations with adverse obstetrical outcomes A scoping review confirmed that complications like premature rupture of membranes and preterm birth occur at markedly higher rates in pregnant women experiencing renal colic than in the general pregnant population.11PubMed Central. Maternal–Fetal Complications in Renal Colic during Pregnancy: A Scoping Review Prolonged hospital stays and increased maternal morbidity have also been documented.12PubMed Central. Labor and Delivery Complications in Women With Renal Calculi: Increased Risk and Prolonged Hospital Stay
Managing Stones While Pregnant
Treatment options narrow considerably during pregnancy. Shock wave lithotripsy, the noninvasive procedure that breaks up stones from outside the body, is contraindicated because the energy waves can harm the fetus. CT scans, the gold-standard imaging for stones, expose the fetus to radiation, so ultrasound becomes the first-line diagnostic tool despite its lower accuracy. Most small stones during pregnancy are managed conservatively with hydration and pain control, and the hope is that the stone will pass on its own.
Tamsulosin, a drug commonly used in non-pregnant adults to relax the ureter and help stones pass, has limited safety data in pregnancy. Small studies suggest that short-term use in the second and third trimesters does not appear to cause adverse maternal or infant outcomes.13PubMed. Safety and efficacy of Tamsulosin as medical expulsive therapy in pregnancy One study found no significant differences in birthweight, gestational age at delivery, or congenital anomalies between women who took tamsulosin and controls.14PubMed. Perinatal Outcomes with Tamsulosin Therapy for Symptomatic Urolithiasis However, the studies are small and the drug remains off-label for use in pregnancy. If a stone is too large to pass or is causing infection or uncontrolled pain, ureteroscopy (passing a thin scope up through the urinary tract to retrieve or fragment the stone) can be performed during pregnancy, typically in the second trimester when the risk to the fetus is lowest.
Metabolic Risk Factors That Hit Women Harder
Several metabolic conditions that disproportionately affect women also raise stone risk. Polycystic ovary syndrome (PCOS), which occurs in up to one in ten women of reproductive age, is linked to obesity, insulin resistance, and higher circulating androgen levels, all of which promote stone formation. Insulin resistance lowers urine pH and citrate levels, creating favorable conditions for both uric acid and calcium stones.15IntechOpen. Urological Associations and Sequalae of PCOS: Urinary Stones, Kidney Disease, Lower Urinary Tract Symptoms and Infections, and Fowler’s Syndrome – Section: PCOS and nephrolithiasis Women who weigh more than 100 kilograms face a nearly 90% increased risk of developing stones compared with women at a lower weight.
Bariatric surgery, which is more commonly undergone by women, introduces its own stone risk. After Roux-en-Y gastric bypass (the type that reroutes part of the intestine), the rate of new kidney stones reaches about 8% at three years and 14% at ten years, roughly double the rate seen in similarly obese controls who did not have surgery.16PubMed Central. Risk Factors for Kidney Stone Formation following Bariatric Surgery The mechanism involves increased absorption of oxalate in the shortened intestine, which then gets excreted by the kidneys in higher concentrations. If you have had this type of surgery, staying well hydrated and discussing oxalate-reduction strategies with a dietitian are especially worthwhile.
Why Men’s and Women’s Urine Chemistry Differs
Even setting aside hormones and pregnancy, baseline urine chemistry differs between the sexes. A study examining the factors behind sex differences in stone risk found that urine supersaturation for calcium oxalate and uric acid was higher in men, primarily because men excrete more oxalate (about 26% more), more uric acid (about 16% more), and more phosphate (about 24% more), and tend to have lower urine pH.17PubMed Central. Factors associated with sex differences in the risk of kidney stones The frequency of hyperoxaluria (excess oxalate in the urine) was about three times more common among men compared with women.18PubMed. Twenty-four-hour urine chemistries and the risk of kidney stones among women and men
These differences help explain why men still form stones more often overall, but they also mean that when women do form stones, the underlying metabolic trigger may be different. Women are relatively more likely to form infection-related stones (struvite stones), which develop when urinary tract infections caused by certain bacteria raise the urine pH and create conditions for a different mineral to crystallize. Women get UTIs far more often than men due to shorter urethral anatomy, so this stone type skews heavily female. Animal research has shown that estrogen exposure itself can promote struvite stone formation, potentially by altering the bladder lining in ways that make infection easier to establish.19PubMed. Effect of estrogen on the formation of struvite calculi in female rats
Diagnosis Challenges Unique to Women
When a woman shows up at the emergency department with sudden, severe flank or lower abdominal pain, kidney stones are on the list of possibilities, but so are several conditions that men simply do not have. Ovarian torsion, ruptured ovarian cysts, and ectopic pregnancy can all mimic the pain of a stone. Case reports document ovarian torsion masquerading convincingly as ureteric colic, discovered only on CT imaging.20PubMed Central. Torsion of ovarian dermoid cyst mimicking obstructing urinary tract stone Because some of these mimics are surgical emergencies, getting the diagnosis right quickly matters more than in a straightforward presentation.
Imaging choices add another wrinkle. CT is the most accurate tool for finding stones, but ultrasound is preferred whenever radiation exposure is a concern, particularly in younger women and during pregnancy. Ultrasound sensitivity for detecting stones is around 77%, and it tends to overestimate stone size, especially in people with a higher BMI. That overestimation can lead to unnecessary surgical interventions in up to 40% of patients whose stones measure over 4 mm on ultrasound but turn out to be smaller on CT.21PubMed Central. Limitations of ultrasound compared with computed tomography for kidney stone surveillance For women who need repeated surveillance imaging over time, this tradeoff between radiation avoidance and diagnostic accuracy is a recurring consideration.
Disparities in Emergency Care
There is emerging evidence that women presenting with kidney stone pain may be treated differently than men even when their clinical picture is essentially the same. A retrospective analysis of emergency department visits for renal colic found no significant differences between men and women in pain scores, stone size, or severity of urinary blockage. Despite this, men were significantly more likely to be admitted to the hospital than women, with admission rates of about 50% versus 38%. Male sex remained an independent predictor of hospital admission even after adjusting for other variables.22PubMed. Sex-based disparities in the management of acute renal colic
A separate study looking specifically at pain management found that men received analgesics more often than women (about 69% versus 62%) and were prescribed opioids at a higher rate (about 48% versus 36%). The number of pain drugs prescribed per patient was also higher for men.23PubMed. Is There Gender Discrimination in Acute Renal Colic Pain Management? A Retrospective Analysis in an Emergency Department Setting These patterns echo broader research showing that women’s pain is more likely to be attributed to emotional or psychological causes, leading to delays in appropriate treatment. If you are a woman experiencing what you think is kidney stone pain, being direct and specific about your symptoms with the emergency team can help ensure you receive timely care.
Post-Surgical Complications in Women
When stones do require surgery, women face a higher risk of one particular complication: sepsis. A systematic review found that all included studies identified female sex as a risk factor for developing sepsis after stone surgery. After ureteroscopy, women had about 60% higher odds of sepsis compared with men. After percutaneous nephrolithotomy, a more invasive procedure for larger stones, the odds were dramatically higher.24PubMed Central. Gender Differences in Kidney Stone Disease (KSD): Findings from a Systematic Review – Section: Post-intervention Sepsis The reasons are not fully established, but the higher baseline rate of UTIs in women likely contributes: bacteria already present in the urinary tract can enter the bloodstream when instruments are passed through during surgery. Pre-operative screening for infection and appropriate antibiotics are especially important for women undergoing these procedures.
Calcium and Vitamin D Supplements After Menopause
Many postmenopausal women take calcium and vitamin D supplements for bone health, and a reasonable concern is whether these supplements increase stone risk. The answer depends on timing and form. Calcium from food tends to be protective because it binds oxalate in the gut, preventing oxalate from being absorbed and reaching the kidneys. Calcium supplements taken between meals, however, miss that binding opportunity, and the extra calcium ends up in the urine without the offsetting oxalate reduction.25PubMed Central. Calcium and Vitamin D Supplementation and Their Association with Kidney Stone Disease: A Narrative Review
The largest randomized trial of calcium and vitamin D in postmenopausal women, part of the Women’s Health Initiative, found that women taking supplements had about 17% more kidney stones than those on placebo. That said, a smaller study in postmenopausal women found no increase in urinary calcium excretion or stone formation after one year of supplementation. The discrepancy may come down to dose, duration, and whether the calcium was taken with meals. For women already at risk for stones, taking calcium supplements with food rather than on an empty stomach, and keeping vitamin D doses moderate, is a practical way to protect bones without unnecessarily pushing stone risk upward.