Surreal illustration of kidney stone formation with rapidly multiplying cells.

Kidney Stones: Is Your Body Triggering Its Own Crystal Crisis?

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Elliot Brynn in Health & Wellness October 2026 • 4 min read.

"New research reveals how urothelial proliferation in the kidneys could be a key factor in the development of renal crystal deposits, offering potential insights for prevention."


Kidney stones, a common ailment affecting a significant portion of the population, are often attributed to factors like diet and hydration. However, emerging research suggests a more complex picture, highlighting the role of processes within the kidney itself.

A recent study delved into the early events of kidney stone formation, specifically focusing on how crystals bind to the inner lining of the kidneys, known as the urothelium. The findings suggest that urothelial proliferation, or the rapid growth of these cells, may be a critical trigger in the development of renal crystal deposits.

This article explores the surprising link between urothelial proliferation and kidney stone formation, drawing on the study's insights to shed light on potential preventative strategies and the future of kidney stone research.

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Stone Composition and U.S. Data

The National Institute of Diabetes and Digestive and Kidney Diseases’ *Urologic Diseases in America: 2024 UDA Data Report* covers the epidemiology of non-malignant urologic disease in the United States. A 2025 study aimed to update population-level information on kidney-stone composition, examining differences by age, gender, and geographic location using specimens submitted to a large tertiary stone-analysis laboratory. Separately, a retrospective analysis of 1,516 patients at a large U.S. stone center found that uric acid stones rose from 7% to 14% of kidney stones between 1980 and 2015.

The Urothelium-Crystal Connection: How Cell Growth Can Lead to Stone Formation

Surreal illustration of kidney stone formation with rapidly multiplying cells.

The study, conducted on a murine model, investigated the effects of vitamin D supplements, along with water containing hydroxyl-L-proline, ammonium chloride, and calcium chloride, on kidney crystal formation. Researchers compared a group receiving Fibroblast Growth Factor 7 (FGF7), a mitogen that stimulates urothelial cell growth, with a control group.

The results revealed that calcium oxalate monohydrate (COM) crystals were detected in the urine as early as day 2, with enhanced deposits in the FGF7 group by day 14. This acceleration suggests a direct link between urothelial proliferation and crystal deposition.

  • Urothelial Proliferation: The FGF7 group exhibited significant urothelial cell proliferation, indicating rapid cell growth in the kidney lining.
  • Uroplakin III Downregulation: A decrease in uroplakin III, a protein found in urothelial cells, was observed in the FGF7 group.
  • CD44 Expression: The FGF7 group showed de novo expression of osteopontin receptor CD44, which plays a role in cell adhesion and crystal retention.
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Research at the Crystal Scale

Recent work spans both clinical and fundamental research on microcrystalline pathologies; its foreword reports 71 references in PubMed and 129 in Web of Science, and notes publications in journals including the *New England Journal of Medicine* and *Kidney International*. A whole-exome-sequencing study identified HSPG2 as a potential causative gene for kidney-stone disease in a Thai family. The study reports that over 40% of cases are concentrated in northeastern Thailand and points to mutations reported in several families as possible evidence of genetic influence. Another study isolated urine fractions with a summed crystal-promoting score of at least 3 for proteomic analysis using nanoLC-ESI-Qq-TOF tandem mass spectrometry.

More Than Urine Chemistry May Matter

A murine lithogenesis study notes that hypercalciuria and hyperoxaluria had been proposed as jointly necessary for calcium phosphate and/or calcium oxalate crystal deposits in mouse kidneys. It also describes additional factors as potentially involved, including a marked resistance to crystal deposition among female mice. These observations complicate an account of crystal formation based only on elevated urinary calcium and oxalate, while remaining findings from a mouse model.

Comparing Prevention and Stone Procedures

An observational study of working-age adults with kidney-stone disease found that empiric preventive pharmacologic therapy with thiazides was associated with lower rates of subsequent stone-related events over three years than alkali citrate or allopurinol. The source notes that the earlier study comparing selective with empiric therapy had significant follow-up bias in the selective-treatment arm and examined only dietary interventions, leaving a knowledge gap. For stones under 2 cm, a prospective single-center cohort source reports that percutaneous nephrolithotomy (PCNL) was more effective than extracorporeal shock wave lithotripsy (ESWL), while also noting complications associated with nephrostomy catheters, including pain, urine leakage, infection, and prolonged hospitalization. A review of urological guidelines compares American Urological Association and European Association of Urology recommendations for stone-disease management.

These changes suggest that urothelial proliferation leads to alterations in cell characteristics, making it easier for crystals to adhere and accumulate. Interestingly, when the mice were switched back to a normal diet on day 21, a spontaneous crystal clearance was observed, underscoring the influence of external factors on crystal formation.

What This Means for You: Preventing Crystal Buildup and Future Research

The study's findings highlight the importance of maintaining a healthy kidney environment to prevent excessive urothelial proliferation. While the research was conducted on animal models, the implications for human health are significant.

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Stone History and Later Cancer Outcomes

A 2025 meta-analysis reports that a history of kidney stones was associated with more than twice the risk of developing upper tract urothelial carcinoma (UTUC) compared with no stone history. Its authors say this supports careful examination of the upper urinary tract during imaging and continued awareness of possible urothelial abnormalities during long-term follow-up. Separately, a cohort study of 3,414 patients with UTUC found that a history of urinary stones was associated with significantly worse cancer-specific and disease-free survival, even after adjustment for confounders using overlap weighting.

Questions for Follow-Up and Future Care

A 2025 meta-analysis found that a history of kidney stones was associated with more than twice the risk of developing UTUC. Its conclusion calls for careful examination of the upper tract during imaging and continued awareness of possible urothelial abnormalities during long-term follow-up. The available future-perspectives source describes a 2024 meeting in Valencia where globally recognized urolithiasis experts discussed the state of the art in urinary-stone management. A Journal of Clinical Medicine special issue is also devoted to current management and future perspectives on kidney stones.

Stones in a Systemic Health Context

A review of urinary stone disease describes associations with systemic conditions including hypertension, diabetes, and other components of metabolic syndrome, and notes that these conditions may in turn contribute to rising stone incidence. A 2023 review says kidney stones frequently manifest underlying systemic conditions such as metabolic syndrome, genetic disorders, or endocrinopathies. It also explains that urine chemistry and stone composition can provide clues to disease mechanisms and guide additional investigations for underlying conditions. A 2025 review examines urinary risk factors and genetic variants in kidney-stone formation.

Diagnosis and Patient Outcomes

An educational case on urinary stones describes noncontrast computed tomography (CT) as the gold standard for diagnosing the favored entity in the differential diagnosis. It notes that ultrasound or an abdominal kidney–ureter–bladder (KUB) radiograph may be used in some cases, while ultrasound interpretation may depend on operator experience. Separately, a 2025 study examined the association between urinary-stone history and renal cell carcinoma and UTUC risk in the Netherlands Cohort Study on diet and cancer.

Future research should focus on identifying specific factors that trigger urothelial proliferation in the kidneys, as well as exploring potential therapeutic interventions to regulate cell growth and prevent crystal adhesion. Understanding these mechanisms could lead to more targeted and effective strategies for preventing kidney stone formation.

By understanding the interplay between urothelial proliferation and crystal formation, we can move closer to personalized strategies for preventing kidney stones and promoting long-term renal health.

What a mouse model can-and cannot-show

Animal study (level 5 of 8)

The study followed mice exposed to a stone-forming regimen and compared animals given FGF7 with saline controls. This design can show how crystal retention and urothelial changes unfolded under those experimental conditions, but it cannot establish that the same process causes kidney stones in people.[1]

Crystal deposits increased during the mouse experiment

  • 60 % of sectionsAt day 42, at least one crystal was present in 60% of the kidney sections examined; this is a section-level share, not the percentage of mice with deposits.[2]

The findings point to retention at the kidney lining

Deposits appeared in specialized urinary recesses in both groups, while FGF7 was associated with greater retention there than the stone-forming regimen alone. The pattern is consistent with a role for urothelial growth in retaining crystals, though the experiment does not show that growth is the only factor involved.[1] [2]

Where this model is least conclusive

  • The authors noted that mice could avoid nephrocalcinosis despite substantial urinary oxalate and calcium, suggesting that natural crystal inhibitors may affect the model’s outcome.[2]
  • The crystal-promoting regimen reduced water intake and urine output compared with controls, which may shape how closely the exposure resembles other settings.[2]

FGF7 and crystal retention in a 42-day mouse model

Study designAnimal study[1]
Duration42 days[1]
ComparisonFGF7 group compared with saline control group[1]
Times cited13[1]

What remains unresolved about crystal retention

  • Would the same relationship between urothelial proliferation and crystal retention appear in settings beyond this induced mouse model?[1]
  • Which urothelial change—cell proliferation, loss of apical uroplakin III plaques, or CD44 expression—contributes most to the increased retention?[1] [2]
  • How do urine conditions and natural crystal inhibitors interact with changes in the urothelium to determine whether crystals remain in the kidney?[1] [2]

Terms used in the study

FGF7
A mitogen used to stimulate urothelial cell growth.[1]

Sources

  1. Urothelium proliferation is a trigger for renal crystal deposits in a murine lithogenesis model (Springer Science and Business Media LLC, 2018)
  2. Urothelium proliferation is a trigger for renal crystal deposits in a murine lithogenesis model (Europe PMC, 2018)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1038/s41598-018-34734-8, Alternate LINK

Title: Urothelium Proliferation Is A Trigger For Renal Crystal Deposits In A Murine Lithogenesis Model

Subject: Multidisciplinary

Journal: Scientific Reports

Publisher: Springer Science and Business Media LLC

Authors: Héloïse Bilbault, Joëlle Perez, Léa Huguet, Sophie Vandermeersch, Sandrine Placier, Nahid Tabibzadeh, Vincent Frochot, Emmanuel Letavernier, Dominique Bazin, Michel Daudon, Jean-Philippe Haymann

Published: 2018-11-05

Everything You Need To Know

1

What is the main focus of the new research regarding kidney stones?

Kidney stones, a common ailment, are often linked to diet and hydration. However, research points to the inner workings of the kidneys. The findings suggest that **urothelial proliferation**, or rapid cell growth in the kidney lining, may be a crucial factor in the formation of these deposits. The article suggests that the kidneys might play a more direct role than previously understood, highlighting internal processes as potential targets for prevention.

2

How does urothelial proliferation contribute to kidney stone formation?

The research indicates that **urothelial proliferation** seems to be a key factor in kidney stone development. This is because the rapid cell growth in the kidney lining alters the environment, making it easier for crystals to stick and accumulate. This was observed in a study where a group of mice received **Fibroblast Growth Factor 7 (FGF7)**, a mitogen that stimulates **urothelial cell growth**, leading to increased crystal deposits. The implications are that if the rapid cell growth can be controlled, the chances of crystal buildup might be reduced.

3

What specific cellular changes occur during urothelial proliferation that promote crystal formation?

The study focused on the **urothelium**, the inner lining of the kidneys, and how it interacts with crystals. The study showed that when the **urothelial proliferation** occurs, there are changes in cell characteristics. In the **FGF7** group, the **urothelial cells** exhibited a decrease in **uroplakin III**, a protein found in the **urothelial cells**. The FGF7 group also showed de novo expression of **CD44**, which aids in crystal retention. These alterations make it easier for crystals, like **calcium oxalate monohydrate (COM)**, to attach and grow. The implications are that strategies targeting these cellular changes could prevent crystal buildup.

4

What are the broader implications of this research for preventing kidney stones?

The implications of this research are significant for understanding and preventing kidney stones. The study highlighted that **urothelial proliferation** and the resulting cellular changes are linked to the buildup of crystals. The study found that when the mice were switched back to a normal diet, the **COM** crystal deposits were spontaneously cleared. This underscores the importance of a healthy kidney environment and the potential for dietary or other interventions to influence crystal formation and dissolution. The study suggests that maintaining a healthy kidney environment is crucial to prevent excessive **urothelial proliferation** and crystal buildup.

5

What was the experimental setup in this research?

The research underscores the importance of the **urothelium** and internal processes in kidney stone formation. The study introduced **vitamin D supplements**, along with water containing **hydroxyl-L-proline, ammonium chloride, and calcium chloride**, which led to **COM** crystal formation. The study then administered **Fibroblast Growth Factor 7 (FGF7)**, which promotes **urothelial proliferation** and crystal deposition. The mice that switched back to a normal diet showed crystal clearance. Researchers are also studying how crystals bind to the **urothelium** and the role of the protein **uroplakin III** and **CD44** expression in crystal retention. These findings suggest various research paths.

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