Calcinosis Universalis Secondary to Silicone Injections in a Patient With HIV and Chronic Kidney Disease: A Case Report of Silicone-Induced Hypercalcemia.

Medical literature has long reported evidence of complications associated with cosmetic procedures, including silicone injections. Recent years have seen an increase in case reports involving hypercalcemia resulting from these injections. A common current hypothesis for the development of hypercalcemia associated with silicone injections is granulomatous inflammation against a foreign body.  This report aimed to describe the case of a 44-year-old African American male with human immunodeficiency virus (HIV) and chronic kidney disease (CKD) who presented to our hospital and was diagnosed with calcinosis universalis secondary to a history of silicone injections, as well as to present a literature review of silicone-induced hypercalcemia. This was a case report (n=1) from a large academic medical center for which the patient, who first presented in May 2023, had two inpatient admissions and two outpatient visits before being lost to follow-up. Relevant images, laboratory results, and treatments were included.  The patient's history was significant for HIV, hypertension, CKD, recurrent nephrolithiasis, and tobacco use disorder. Physical examination was positive for flank pain while labs were significant for Na 137 mmol/L, K 2.7 mmol/L, blood urea nitrogen (BUN) 28 mg/dL, creatinine 3.72 mg/dL, calcium 13.4 mg/dL, hemoglobin 9.3 g/dL, white blood cell count 6,700 u/L and platelet count 105,000 u/L. Renal ultrasound revealed bilateral nephrolithiasis and left-sided hydronephrosis. Computerized tomography (CT) upon admission showed hyperlucid deposits in the bilateral gluteal area. Initial management included intravenous (IV) fluids and one dose of IV pamidronate, which resulted in reduced calcium levels during the admission. Subsequent management included outpatient follow-up with endocrinology during which denosumab was prescribed. This case had similar findings to other reports in the literature detailing silicone-induced hypercalcemia, which also reported abnormal imaging or nephrolithiasis, low-normal parathyroid hormone (PTH), normal 25-hydroxyvitamin D, and elevated 1,25-dihydroxyvitamin D. Silicone injection-induced hypercalcemia should be considered as a differential diagnosis in patients presenting with otherwise unexplained elevated serum calcium and a history of past cosmetic procedures. If suspected, the use of imaging techniques (e.g. positron emission tomography (PET) scans or MRI) may help ascertain the diagnosis. Further research is needed to determine the most appropriate therapies for complex patients such as those with immunodeficiency or renal disease.

Between a Rock and a Short Place-The Impact of Nephrolithiasis on Skeletal Growth and Development Across the Lifespan.

PURPOSE OF REVIEW: The impact of nephrolithiasis on skeletal growth and bone health across the life span of kidney stone formers is reviewed. MAIN FINDINGS: Bone disease is an early event among kidney stone formers (SF), with distinct phenotypes according to each age, sex, menopausal status, dietary, hormonal and genetic factors. Nephrolithiasis-associated bone disorder is characterized by reduced bone mineral density (BMD) and histologically discloses low bone formation, high bone resorption and abnormal mineralization. Although hypercalciuria has been presumed to be pathogenic for bone loss in SF, the association of BMD with urinary calcium is not uniform in all studies. Hypocitraturia, metabolic disturbances, cytokines and receptors, growth factors and acid-base status may all influence skeletal outcomes. The potential link of bone disease with vascular calcification and cardiovascular disease among SF is discussed. The unique vulnerability of the younger skeleton to the effects of nephrolithiasis on attainment of peak bone mass and strength is highlighted and the association of bone loss with kidney stone formation early in life indicate the opportunity for intervention to reduce the risk of future bone fractures.

Sodium-glucose cotranspor ter 2 (SGLT2) inhibitors in nephrolithiasis: should we "gliflozin" patients with kidney stone disease? / Inibidores de cotransportadores sódio-glicose-2 (SGLT2) na nefrolitíase - devemos "gliflozinar" os litiásicos?

ABSTRACT The prevalence of nephrolithiasis is increasing worldwide. Despite advances in understanding the pathogenesis of lithiasis, few studies have demonstrated that specific clinical interventions reduce the recurrence of nephrolithiasis. The aim of this review is to analyze the current data and potential effects of iSGLT2 in lithogenesis and try to answer the question: Should we also "gliflozin" our patients with kidney stone disease?

RESUMO A prevalência da nefrolitíase está aumentando em todo o mundo. Apesar dos avanços na compreensão da patogênese da doença litiásica, poucos estudos demonstraram que intervenções clínicas específicas diminuem a recorrência da nefrolitíase. O objetivo desta revisão é analisar os dados atuais e efeitos potenciais dos iSGLT2 na doença litiásica e tentar responder à pergunta: devemos também "gliflozinar" os litiásicos?

Xanthogranulomatous Pyelonephritis: A pooled quantitative analysis of published cases.

Xanthogranulomatous Pyelonephritis (XGP) is a serious and rare inflammatory disease of unknown etiology. This systematic review analyzes XGP cases. We performed a literature search for "Pyelonephritis, Xanthogranulomatous." The primary composite outcome was recovery with post-surgery complications, partial recovery, death, or chronic kidney disease. The secondary outcome was any presentation or treatment complication. Predictor variables consisted of demographics, history, symptoms, and diagnosis/management. Among the 251 patients, the mean age was 36.1 years, and 57.4% were female. The most common symptom and finding were fever (55.0%) and renal stones (53.8%), respectively. There were 15.5% with the composite outcome. There were 51.0% with any presentation or treatment complication. Multivariate logistic regression analysis for the composite outcome showed that kidney of both/horseshoe (OR:3.86, 95% CI:1.01, 14.73, p = 0.048), dialysis required (OR:8.64, 95% CI:2.27, 32.94, p = 0.002), and operative treatment of nephrostomy or nephrostomy followed by nephrectomy (OR:4.57, 95% CI:1.58, 13.17, p = 0.01) were each significantly associated with increased odds. Fever (OR:3.04, 95% CI:1.63, 5.67, p <0.001) and renal stones (OR:2.55, 95% CI:1.35, 4.81, p = 0.004) were each significantly associated with increased odds for any presentation/treatment complication. In conclusion, XGP patients with involvement of both or horseshoe kidneys, dialysis requirements, or treatment of nephrostomy or nephrostomy followed by nephrectomy may require aggressive treatment to mitigate poor patient outcomes.

Chronic Kidney Disease and Kidney Stone in a Wild Chimpanzee (Pan troglodytes verus) in Côte d'Ivoire.

An older wild female chimpanzee (Pan troglodytes) was found dead with a large calcium oxalate stone in the renal pelvis. Histopathological changes included glomerulosclerosis, interstitial nephritis and fibrosis, focal mineralization, and medial hypertrophy. Urinary albumin-creatinine-ratio showed increased values from 15 months before death. Causes of the kidney disease remain unconfirmed.

Expression Profiles of Claudin Gene Family Members in Patients With Recurrent Calcium Oxalate Kidney Stones.

INTRODUCTION: In this study, we aimed to evaluate and compare the expression profiles of CLDN gene family members responsible for the mechanism of stone formation in patients with recurrent calcium oxalate stones and in a control group without a history of renal stones. METHODS: Nineteen patients with recurrent calcium oxalate renal calculi who underwent percutaneous nephrolithotomy and 21 control patients without renal calculi who underwent surgery for other reasons were included in the study. The urinary calcium, oxalate, and citrate levels of the patients included in the study, as well as those in the control group, were within normal ranges. They did not have proteinuria in their urine. The biochemical parameters were also within normal limits. Biopsy samples taken from the intact renal cortex parenchymal tissue were consistent. Total RNA was isolated from biopsy samples and expression profiles of target genes (Claudin 1-4, 7, 8, 10, 14, 16, 18, 19) were determined by real-time polymerase chain reaction (PCR). RESULTS: It was determined that CLDN1 gene expression in patients with recurrent calcium oxalate kidney stones was approximately four times higher than in the control group; this difference was statistically significant (p<0.050). CLDN1 expression was also strongly positively correlated with CLDN4 (r=0.642), CLDN7 (r=0.753) and CLDN14 (r=0.651) Conclusions: We thought that CLDN1 overexpression might play a role in the pathogenesis of recurrent calcium oxalate stone formation. CLDN1 together with CLDN2, CLDN4, CLDN7, and CLDN14 are also probably responsible for this pathogenesis.

Two distinct phenotypes of calcium oxalate stone formers could imply different long-term risks for renal function.

Endoscopic and biopsy findings have identified two distinct phenotypes among individuals with calcium oxalate (CaOx) kidney stones. The first type has normal renal papillae but shows interstitial mineral deposition, known as Randall's plaque. The other phenotype presents with collecting duct plugging and a higher incidence of loss of papilla tissue mass. With Randall's plaque, renal papilla injury involves the loss of small patches of calcified tissue (Randall's plaque detaching with the stone), which likely results in damage to only a few nephrons. In contrast, collecting duct mineral plugs are very large, causing obstruction to tubular flow. Since each terminal collecting duct drains thousands of nephrons, ductal plugs could lead to the degeneration of many nephrons and a significant loss of renal glomeruli. New visualization techniques for immune cells in papillary biopsies have revealed that the Randall's plaque phenotype is marked by the accumulation of macrophages around the plaque regions. In contrast, preliminary data on the plugging phenotype shows collecting duct damage with mineral plugs and increased T-lymphocytes throughout the papilla. These regions also show tubulitis, i.e., T-cell infiltration into nearby collecting duct epithelium. This suggests that while some CaOx stone formers may have some papillary inflammation but with minimal damage to nephrons, others suffer from obstruction to flow for many nephrons that may also include destructive inflammation in the renal tissue. We propose that CaOx stone formers with the plugging phenotype will have a higher long-term risk for loss of renal function.

Bilateral nephrolithiasis and upper tract transitional cell carcinoma in horseshoe kidney.

Nephroureterectomy is currently the criterion-standard treatment for high-grade upper tract urothelial carcinoma (UTUC). Current guidelines and expert opinions propose some exceptions to this approach based on patient characteristics, disease status, and function of the contralateral kidney. We present a rare case of a patient with horseshoe kidney, bilateral large nephrolithiasis, high-grade UTUC in one moiety, and relative parenchymal thinning of the contralateral side. The patient was treated with a percutaneous, minimally invasive, nephron sparing approach. The patient also had intracollecting system instillations of gemcitabine and docetaxel. Minimally invasive percutaneous resection of high-grade UTUC is a safe procedure in select cases. Current guidelines may not apply to all patients; unique scenarios with UTUC may require personalized decision-making and treatment at specialized centers.

Calyceal Rupture Secondary to Nephrolithiasis: A Case Report Emphasizing Early Diagnosis and Management.

Calyceal rupture, defined as the extravasation of urine from the renal calyces into the perinephric or paranephric spaces, typically results from increased intrapelvic pressure due to urinary tract obstruction. This condition can lead to the formation of a perinephric urinoma and severe complications, such as infection, abscess formation, and impaired renal function. Timely diagnosis and management are crucial to prevent these adverse outcomes. Calyceal rupture often results from urolithiasis, with other causes including strictures, tumors, and congenital abnormalities. The rupture occurs when intrapelvic pressure exceeds the tensile strength of the calyceal walls, leading to urine leakage and potential inflammation or sepsis. Calyceal ruptures are quite rare, with their exact incidence not well-documented due to the infrequency of the condition and potential underreporting. Although relatively uncommon, the condition is more prevalent in individuals with recurrent nephrolithiasis and other predisposing factors. Timely recognition and intervention, guided by imaging studies such as non-contrast CT scans, are essential. Conservative management with medical therapy is effective in many cases, but surgical intervention may be necessary for larger stones or complications. This report presents the case of a 36-year-old female with calyceal rupture secondary to nephrolithiasis, presenting with severe flank pain. Upon initial presentation, the patient underwent a thorough workup, including imaging studies, appropriate medical management, and continuous monitoring. She was stabilized, her pain was effectively managed, and she was discharged with a scheduled outpatient follow-up. This case highlights the importance of early diagnosis, comprehensive management, and vigilant monitoring in preventing complications and promoting favorable outcomes.

Effects of SLC34A3 or SLC34A1 variants on calcium and phosphorus homeostasis.

BACKGROUND: Variants in SLC34A1 and SLC34A2 genes, which encode co-transporters NaPi2a and NaPi2c, respectively, can lead to hypophosphatemia due to renal phosphate loss. This condition results in hypercalcitriolemia and hypercalciuria, leading to formation of kidney stones and nephrocalcinosis. Phenotype is highly variable. Management includes hyperhydration, dietary modifications, and/or phosphate supplementation. Thiazides and azoles may be used, but randomized studies are needed to confirm their clinical efficacy. METHODS: We conducted a retrospective study in the pediatric nephrology unit at Grenoble University Hospital from January 2010 to December 2023. The study aimed to describe clinical and biological symptoms of patients with confirmed SLC34A1 and SLC34A3 gene variants and their outcomes. RESULTS: A total of 11 patients (9 females) from 6 different families had variants in the SLC34A1 (5 patients) and SLC34A3 (6 patients) genes. Median age at diagnosis was 72 [1-108] months. Average follow-up duration was 8.1 ± 4.5 years. Presenting symptom was nephrocalcinosis (4 cases), followed by renal colic (3 cases). At diagnosis, 90% of patients had hypercalciuria and 45% had hypercalcitriolemia. Management included hyperhydration and dietary advice. All patients showed favorable outcomes with normal growth and school attendance. One patient with an SLC34A3 variant showed regression of nephrocalcinosis. Kidney function remained normal. CONCLUSION: Clinical and biological manifestations of SLC34 gene variants are highly variable, even among siblings; therefore, management must be personalized. Hygienic and dietary measures (such as hyperhydration, a low sodium diet, and age-appropriate calcium intake) result in favorable outcomes in most cases. Use of azoles (e.g., fluconazole) appears to be a promising therapeutic option.

Influence of Dietary Heritage in a Restricted Geographic Area and Role of Food Additives on Risk of Recurrent Kidney Stone.

Dietary factors may be implicated in the formation of kidney stones and should be closely monitored. To achieve this aim, patients are routinely assessed by means of generic dietary recall, a tool widely used by authors in a range of extensive patient populations to record food intake; the findings obtained, however, may be skewed due to dietary variations and underestimation of the effect of food additives. Fifty Frequent Kidney Stone Formers (FKSFs, mean age: 54.3 ± 13.9 years) with normal kidney function, absence of comorbidities, and reliable compliance were selected from a total of 68 patients' resident in Sardinia, an Italian island where genetic admixtures have been relatively rare for generations. The study, conducted from 1 January 2020 to 31 December 2023, was aimed at assessing nutritional values based on the meticulous recording of food quantities, quality, and potential modifications related to food preparation. Patients were selected during an initial clinical check-up and all efforts made to ensure they were capable of reliably recording all food and drinks consumed. A seven-day food diary was provided in which food and drink intake and their impact on 24 h urine output was recorded. The following parameters were measured in both foods and urine output: citrates, oxalates, calcium, phosphorous, uric acid, proteins and nitrogen compounds, magnesium, sulfates, potassium, carbohydrates, free fatty acids. Study outcomes established the presence of hypocitraturia, hyperoxaluria, hypercalciuria, and moderately high levels of nitrogen compounds. Univariate analysis followed by multivariate analysis for further confirmation were performed and the following observations made. Citrate intake correlated with citraturia but did not promote oxaluria; calcium intake promoted onset of sulfaturia, azoturia, and ammoniuria, whilst magnesium correlated with magnesiuria but not with oxaluria, calciuria, phosphaturia, and azoturia; sulfate intake elicited onset of azoturia but not kaliuresis; potassium intake promoted oxaluria and protein intake resulted in onset of ammoniuria and azoturia. (A) The chemical composition of urine based on dietary intake is hard to predict without taking into account the presence of dietary and urinary interferents; (B) the geographic isolation of patients studied underlines the importance of epigenetics in maintaining a traditional dietary heritage. (C) Moreover, the widespread use of food additives should consistently be taken into account to ensure a correct diagnosis of FKSF and set up a valid treatment plan.

Immune-inflammatory process in nephrolithiasis: A bibliometric analysis (2000-2023).

The research on the mechanism of nephrolithiasis formation is of great importance due to the fact that the high incidence and recurrence rate of nephrolithiasis bring considerable economic burdens to patients and society. As an important component in the nephrolithiasis formation process, the immune-inflammatory process has been gradually valued by researchers in recent years. In this study, articles related to the immune-inflammatory process of nephrolithiasis published since 2000 were retrieved based on the Web of Science (WoS) database. Eventually, a total of 370 articles were selected for subsequent analyses. Besides, VOSviewer, CiteSpace, and Bibliometrix were employed to quantitatively analyze and visualize the data. The number of articles related to the immune-inflammatory process of nephrolithiasis has increased rapidly in the last five years. From the country level, most articles were contributed by China (n = 140) and the United States (n = 99) contributed the most documents. From the institution level, University of Florida (n = 36) and Nagoya City University (n = 21) had the most articles. From the journal level, Journal of Urology and Urolithiasis published the most articles in this field. Keywords mainly included inflammation, oxidative stress, calcium oxalate, osteopontin, and hyperoxaluria, which represented the research directions in this field. The most productive author was Khan SR (n = 33), whose articles obtained the highest number of citations (2086 times). These efforts may help researchers understand the current progress and status of research on the immune-inflammatory process of nephrolithiasis and identify future research hotspots and directions.

Comparison of cat stone matrix and cat urine proteomes to human calcium oxalate stone matrix and urine proteomes.

Cat calcium oxalate monohydrate kidney stone matrix proteome showed great similarity to human calcium oxalate monohydrate stone matrix proteome, but inference of mechanistic similarity was limited by the absence of cat urine proteomic data. In this study, urine proteome distributions were measured by the same methods in 7 healthy cats for comparison to both the published human urine and cat calcium oxalate stone matrix proteomes to assess for similar enrichment patterns in both species. Furthermore, proteomic distributions were determined in cat struvite stone matrix to test for similarity to calcium oxalate monohydrate stone matrix and urine proteomes. Cat urine proteins demonstrated a similar distribution of abundance as a function of isoelectric points or net charge to human urine samples, and consequently the similarly altered patterns of protein distributions seen in calcium oxalate monohydrate stone matrix seen from both cat and human stones likely derives from the same preferential adsorption mechanism. Furthermore, the fact that protein abundance patterns seen in cat struvite stone matrix samples differ from both urine and calcium oxalate monohydrate stone matrix proteomes in systematic ways suggests that a combination of protein-protein and protein crystal interactions underly the formation of the crystal aggregates that comprise stones.

Two distinct phenotypes of calcium oxalate stone formers could imply different long-term risks for renal function.

Endoscopic and biopsy findings have identified two distinct phenotypes among individuals with calcium oxalate (CaOx) kidney stones. One phenotype exhibits normal renal papillae but shows interstitial mineral deposition, known as Randall's plaque. The other phenotype presents with collecting duct plugging and a higher incidence of loss of papilla tissue mass. With Randall's plaque, renal papilla injury involves the loss of small patches of calcified tissue (Randall's plaque detaching with the stone), which likely results in damage to only a few nephrons. In contrast, collecting duct mineral plugs are very large, causing obstruction to tubular flow. Since each terminal collecting duct drains thousands of nephrons, ductal plugs could lead to the degeneration of many nephrons and a significant loss of renal glomeruli. New visualization techniques for immune cells in papillary biopsies have revealed that the Randall's plaque phenotype is marked by the accumulation of macrophages around the plaque regions. In contrast, preliminary data on the plugging phenotype shows collecting duct damage with mineral plugs, increased T-lymphocytes throughout the papilla, and tubulitis, characterized by T-cell infiltration into nearby collecting duct epithelium. This suggests that while some CaOx stone formers may have some papillary inflammation but with minimal damage to nephrons, others suffer from obstruction to flow for many nephrons that may also include destructive inflammation in the renal tissue. We propose that the long-term risks for loss of renal function will be greater for CaOx stone formers with the plugging phenotype.

Prospective study investigating the influence of nutritional intervention on biochemical profiles in patients with recurrent urolithiasis.

BACKGROUND AND OBJECTIVES: Urolithiasis, commonly known as kidney stones, is a condition significantly impacted by dietary habits. The objective of this study is to evaluate the impact of a tailored dietary plan on the crystalluria and biological parameters of patients with different types of kidney stones over a 3-month period. METHODS AND STUDY DESIGN: We conducted a prospective study of 3 months. The study involved patients with recurrent nephrolithiasis. Alongside the medical consultation, a comprehensive dietary survey was performed to assess the patients' nutritional habits. Urinary parameters, including volume, calcium, oxalate, uric acid, and power of hydrogen (pH), were evaluated both before and after the dietary intervention. RESULTS: 69 patients were involved. There were 17 patients diagnosed with cystine lithiasis, 33 with oxalocalcic lithiasis and 19 with uric lithiasis. After 3 months, only 32 patients revisited for follow-up. There were significant changes (p = 0.002 and 0.04) in urine crystalluria for cystinic and uric lithiasis. For the urinary oxalate variation, there was a significant decrease from T1 (before dietary intervention) to T2 (after dietary intervention), with levels dropping from 0.289 ± 0.10 umol/l to 0.215 ± 0.079 umol/l (p = 0.02).Regarding urinary calcium (calciuria), there was a trend toward a decrease from T1 to T2, although the change was not statistically significant, with levels decreasing from 2.42 ± 1.68 umol/l to 2.14 ± 1.62 umol/l (p = 0.1). CONCLUSIONS: Our research underscores the favorable effects of a tailored and well-balanced diet on both the crystalluria and biological parameters of individuals with recurrent lithiasis.

The Effect of Anesthesia Type on the Stability of the Surgical View on the Monitor in Retrograde Intrarenal Surgery for Renal Stone: A Prospective Observational Trial.

Background and Objectives: Retrograde intrarenal surgery (RIRS) is a minimally invasive technique for nephrolithiasis. RIRS is performed via a monitor screen displaying a magnified surgical site. Respiration can affect the stability of the surgical view during RIRS because the kidneys are close to the diaphragm. The purpose of this trial is to compare the effect of anesthesia type on the stability of the surgical view during RIRS between spinal anesthesia and general anesthesia. Materials and Methods: Patients were allocated to the general anesthesia group or spinal anesthesia group. During surgery, movement of the surgical field displayed on the monitor screen was graded by the first assistant on a 10-grade numeric rating scale (0-10). Next, it was also graded by the main surgeon. After surgery, we evaluated the discomfort with the anesthesia method for all patients. Results: Thirty-four patients were allocated to the general anesthesia group and 32 patients to the spinal anesthesia group. The average values of the two surgeons for surgical field oscillation grade showed vision on the monitor screen was more stable in the general anesthesia group than the spinal anesthesia group (3.3 ± 1.6 vs. 5.0 ± 1.6, p < 0.001). The degrees of the inconvenience of the surgery did not differ between the groups (0.7 ± 1.8 vs. 1.6 ± 2.6, p = 0.114), even though more patients reported inconvenience with a grade of 3 or more in the spinal anesthesia group (8.8% vs. 28.1%, p = 0.042). Conclusions: In terms of the visualization of the surgical site, general anesthesia might provide a more stable surgical view during RIRS compared to spinal anesthesia without increasing inconvenience induced by the type of anesthesia.

SGLT-2 inhibitors and nephrolithiasis risk: a meta-analysis.

BACKGROUND AND AIM: Sodium-glucose cotransporter (SGLT)-2 inhibitors are novel anti-diabetic medications with potential beneficial effects on cardiovascular and renal outcomes, metabolic parameters, and body weight. In addition to the beneficial effects on renal functions, including estimated glomerular filtration rate and reduction in proteinuria, recent studies have investigated the potential role of SGLT-2 inhibitor therapy on nephrolithiasis development. Nephrolithiasis, a condition affecting almost 10% of the general population at least once during a lifetime, is a common disorder with considerable risk for acute and chronic kidney injury and relatively few effective therapeutic options. MATERIALS AND METHODS: We have performed a literature search through multiple databases, including PubMed, Ovid/Medline, Web of Science, Scopus, and Cochrane Library. We have followed the systematic review and meta-analysis guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses.We have included a total of 11 635 698 patients who experienced nephrolithiasis from six clinical trials to conduct this meta-analysis study. In the pooled analysis, nephrolithiasis occurred in 1,27% of patients from the SGLT2i group (n = 739 197), compared to 1,56% of patients (n = 10 896 501) from the control arm (active control, placebo or no therapy). RESULTS: We have included a total of 11 635 698 participants who experienced nephrolithiasis from a total of six clinical studies with nephrolithiasis rates of 1,27% in the SGLT2i group (n = 739 197), compared to 1,56% in the control arm (n = 10 896 501). SGLT-2 inhibitor therapy has been associated with a lower risk for nephrolithiasis compared to placebo (OR 0.61, 95% CI, 0.53-0.70, p < 0.00001) or active therapy such as glucagon-like peptide 1 and dipeptidyl peptidase-IV inhibitors (OR 0.66, 95% CI, 0.47-0.93, p = 0.02). CONCLUSION: We have demonstrated a lower risk of nephrolithiasis risk with SGLT-2 inhibitor therapy compared to placebo or active control. Potential underlying mechanisms include osmotic diuresis leading to a reduction in the concentration of lithogenic substances, anti-inflammatory and anti-fibrotic effects, and an increase in urine pH. There is a clear need for future large-scale randomized clinical trials evaluating such associations for better understanding.

First reported magnesium pyrophosphate kidney stone prompts diagnosis of hypophosphatasia.

Hypophosphatasia (HPP) is a rare genetic condition associated with poor bone mineralization, low serum alkaline phosphatase, high urinary pyrophosphate excretion, and nephrocalcinosis. Nephrocalcinosis is thought to develop due to the increased filtered loads associated with hypercalcemia and hyperphosphatemia, but the composition of these calcifications is incompletely understood. We report the first ever magnesium pyrophosphate (MgPPi) urinary stone, which prompted the new diagnosis of HPP in a 12-year-old boy. Stone analysis labs should include infrared spectra of PPi salts in their reference libraries to facilitate identification of these rare but clinically important stones.

A Novel Machine-Learning Algorithm to Predict Stone Recurrence with 24-Hour Urine Data.

Objectives: The absence of predictive markers for kidney stone recurrence poses a challenge for the clinical management of stone disease. The unpredictability of stone events is also a significant limitation for clinical trials, where many patients must be enrolled to obtain sufficient stone events for analysis. In this study, we sought to use machine learning methods to identify a novel algorithm to predict stone recurrence. Subjects/Patients and Methods: Patients enrolled in the Registry for Stones of the Kidney and Ureter (ReSKU), a registry of nephrolithiasis patients collected between 2015-2020, with at least one prospectively collected 24-hour urine test (Litholink 24-hour urine test; Labcorp) were included in the training set. A validation set was obtained from chart review of stone patients not enrolled in ReSKU with 24-hour urine data. Stone events were defined as either an office visit where a patient reports symptomatic passage of stones or a surgical procedure for stone removal. Seven prediction classification methods were evaluated. Predictive analyses and receiver operator characteristics (ROC) curve generation were performed in R. Results: A training set of 423 kidney stone patients with stone event data and 24-hour urine samples were trained using the prediction classification methods. The highest performing prediction model was a Logistic Regression with ElasticNet machine learning model (area under curve [AUC] = 0.65). Restricting analysis to high confidence predictions significantly improved model accuracy (AUC = 0.82). The prediction model was validated on a validation set of 172 stone patients with stone event data and 24-hour urine samples. Prediction accuracy in the validation set demonstrated moderate discriminative ability (AUC = 0.64). Repeat modeling was performed with four of the highest scoring features, and ROC analyses demonstrated minimal loss in accuracy (AUC = 0.63). Conclusion: Machine-learning models based on 24-hour urine data can predict stone recurrences with a moderate degree of accuracy.