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Abstract Background Nephrocalcinosis is common in cats with nephrolithiasis. Understanding the association between these disorders might facilitate understanding of their pathogenesis. Hypothesis/Objectives Nephrocalcinosis is associated with nephrolithiasis. Animals Kidneys were evaluated postmortem in 175 client-owned cats. Methods An observational cross-sectional study. High-resolution microradiography identified nephroliths and classified parenchymal mineralization as striated or punctate. Percentage mineralization was quantified on microradiographs. Associations of nephrocalcinosis and nephrolithiasis at cat level (disease in either the left or right kidney) and individual kidney level were estimated using chi-squared tests and logistic regression with odds ratios (ORs) and 95% confidence intervals (CIs). Results Nephrolithiasis was present in 54% of cats (95/175) and nephrocalcinosis in 84% (147/175). Cats with nephroliths were older than those without (median, 15 vs 13 years; P = .004). At the cat level, nephrocalcinosis was associated with higher odds of nephrolithiasis (OR, 3.5; 95% CI, 1.6-7.4; P = .002), but the association was attenuated after age adjustment (OR, 3.1; 95% CI, 1.0-10.1; P = .05; n = 115). At the kidney level, striated mineralization was associated with nephrolithiasis (OR, 13.9; 95% CI, 2.0-95.9; P = .01), whereas punctate mineralization was not significantly associated with nephrolithiasis. Percentage mineralization was higher in cats with nephroliths than in those without it (P = .004). Conclusions and clinical importance Nephrocalcinosis, particularly striated medullopapillary patterns, was associated with nephrolithiasis in cats. Pattern-specific mineralization may represent a preventive target for the management of nephrolithiasis.

Abstract Background Microscopic nephrocalcinosis is a common pathological feature of chronic kidney disease (CKD) in cats. Detection of macroscopic nephrocalcinosis using ultrasonography and its implications remain unexplored. Objectives Identify risk factors associated with ultrasound-diagnosed nephrocalcinosis and evaluate the influence of nephrocalcinosis on CKD progression. Animals Thirty-six euthyroid client-owned cats with CKD. Methods Prospective cohort study. Cats with CKD with and without ionized hypercalcemia were enrolled for renal ultrasonography. Cats were categorized according to the presence or absence of ultrasound-diagnosed nephrocalcinosis. Binary logistic regression was performed to identify nephrocalcinosis risk factors. The influence of nephrocalcinosis on CKD progression was assessed using linear mixed models. Results Ultrasound-diagnosed nephrocalcinosis was evident in 61% of CKD cats overall, with increased prevalence (81%) in those with hypercalcemia. At enrollment, higher blood ionized calcium concentration (odds ratio [OR], 1.27 per 0.1 mg/dL; P = .01), plasma phosphate concentration (OR, 1.16 per 0.1 mg/dL; P = .05), plasma creatinine concentration (OR, 1.29 per 0.1 mg/dL; P = .02) and alanine aminotransferase activity (OR, 2.08 per 10 U/L; P = .04) were independent nephrocalcinosis risk factors. The rate of change in log-transformed fibroblast growth factor-23 differed significantly between groups (P = .04). Cats with CKD and nephrocalcinosis had increasing plasma creatinine concentrations (.03 ± .01 mg/dL/month; P = .04) and phosphate concentrations (.06 ± .02 mg/dL/month; P < .001) and decreasing body weight (.02 ± .01 kg/month; P < .001) over time. Conclusions and Clinical Importance Nephrocalcinosis is prevalent in cats with CKD, especially in those with hypercalcemia. This pathological feature appears to be associated with CKD progression in cats.

Background Nephrocalcinosis (NC) is characterized by an excessive accumulation of calcium deposits in the kidneys. In children, it is often incidentally discovered with an uncertain prognosis. Case-diagnosis/treatment A 3-month-old girl suspected to have a milk protein allergy underwent an ultrasound that revealed increased echogenicity in the kidney pyramids suggestive of medullary NC. At the age of 18 months, imaging findings revealed not only hyperechogenicity in the medulla but also in the cortex. Over the course of a long follow-up, her kidneys maintained size within the upper limits but showed an increase by age 7. Genetic analysis identified PKHD1 variants, which required structural predictive tools to guide clinical diagnosis. Until the age of 7, her kidney function has remained intact; however, her prognosis is uncertain. Conclusions NC in newborns is a rare condition, but its incidence is rising. Recurrent urinary infections or kidney stones may lead to kidney failure. A proactive approach in sporadic NC enables an early diagnosis to orientate clinical supervision and facilitates counseling to support family planning decisions.

The case of a 41-year-old female patient, with progressive decrease in kidney function, and ultrasound evidencing nephrocalcinosis and nephrolithiasis aims to highlight the importance of interdisciplinary collaboration to diagnose kidney stone diseases and the role of kidney imaging in the evaluation of nephrocalcinosis and nephrolithiasis. Primarily based on abdominal imaging and kidney impairment, the patient was referred to a nephrologist, who diagnosed her with a rare genetic disease, primary hyperoxaluria type 1, with a severe prognosis if not properly and timely treated. The kidney imaging was crucial for the etiologic diagnosis and follow-up of the specific treatment response.

Background Mutation specific effects in monogenic disorders are rare. We describe atypical Fanconi syndrome caused by a specific heterozygous mutation in HNF4A. Heterozygous HNF4A mutations cause a beta cell phenotype of neonatal hyperinsulinism with macrosomia and young onset diabetes. Autosomal dominant idiopathic Fanconi syndrome (a renal proximal tubulopathy) is described but no genetic cause has been defined. Methods and Results We report six patients heterozygous for the p.R76W HNF4A mutation who have Fanconi syndrome and nephrocalcinosis in addition to neonatal hyperinsulinism and macrosomia. All six displayed a novel phenotype of proximal tubulopathy, characterised by generalised aminoaciduria, low molecular weight proteinuria, glycosuria, hyperphosphaturia and hypouricaemia, and additional features not seen in Fanconi syndrome: nephrocalcinosis, renal impairment, hypercalciuria with relative hypocalcaemia, and hypermagnesaemia. This was mutation specific, with the renal phenotype not being seen in patients with other HNF4A mutations. In silico modelling shows the R76 residue is directly involved in DNA binding and the R76W mutation reduces DNA binding affinity. The target(s) selectively affected by altered DNA binding of R76W that results in Fanconi syndrome is not known. Conclusions The HNF4A R76W mutation is an unusual example of a mutation specific phenotype, with autosomal dominant atypical Fanconi syndrome in addition to the established beta cell phenotype.

A 40-year-old man with end-stage kidney disease and calcium oxalate nephrolithiasis presented to the emergency department with joint pain. A workup was notable for nephrocalcinosis on imaging; dense, metaphyseal bands on radiography of the hands; and calcium deposition in the cornea and skin. A diagnosis of primary hyperoxaluria was made by means of genetic testing.

Background Nephrocalcinosis, characterized by excessive calcium deposition within the renal parenchyma, can be a long-term complication of anorexia nervosa (AN). The extent of renal calcification can range from molecular-level alterations to macroscopic stone formation, contributing to progressive kidney injury. While early detection is critical for prognosis, limited studies have characterized the structural and elemental composition of renal calcifications associated with AN. Here, we report a case of nephrocalcinosis in the setting of AN. Case presentation A 25-year-old woman with AN presented with progressive renal dysfunction and gouty arthritis. Renal biopsy revealed focal tubulointerstitial nephritis with extensive calcification. Conventional light microscopy identified crystalline deposits within the tubular lumen, but further characterization required advanced imaging techniques. Low-vacuum scanning electron microscopy (LV-SEM) of formalin-fixed paraffin-embedded (FFPE) specimens demonstrated more widespread crystalline deposits than were visible by routine histopathology. Elemental analysis via energy-dispersive X-ray spectrometry (EDX) confirmed that the deposits were primarily composed of calcium phosphate. Conclusions These findings underscore the utility of LV-SEM/EDX in detecting and characterizing renal calcifications at high resolution. The ability to perform elemental analysis on FFPE tissue sections provides a novel and practical approach for elucidating the pathogenesis of nephrocalcinosis. These methods may enhance the accuracy of renal crystal identification, thereby facilitating earlier diagnosis and improved management of nephrocalcinosis.

A retrospective statistical analysis of primary hyperoxaluria type 1 (PH1) in children from June 2016 to May 2019 was carried out to discover its clinical and molecular biological characteristics. Patients were divided into two groups (infant and noninfant) according to clinic type. There were 13 pediatric patients (male:female = 6:7) with PH1 in the cohort from 11 families (four of which were biological siblings from two families), whose median age of symptom onset was 12 months and median confirmed diagnosis age was 14 months. Infant type (6 patients) was the most common type. The infant type mortality rate (100%) was higher than the noninfant (14.3%) (p = 0.029). The incidence of renal failure in infant patients was 67%, while the noninfant was 14.3%. 8 of 10 patients with nephrocalcinosis (NC) (76.92%, 10/13) were diagnosed by radiological imaging examinations, including X-ray (3 patients), CT (4 patients) and MRI (1 patient). NC was an independent risk factor for renal insufficiency [OR 3.33, 95% CI (0.7–1.2)], p < 0.05). Nine types of AGXT gene mutations were found; 1 type, c.190A > T, were first reported here. The most common AGXT gene mutation was c.679_680del, which occurred in exon 6 (5 patients). The infant type is the most common type of pediatric PH, with a relatively higher ratio of renal failure at symptom onset and poor prognosis. NC is an independent risk factor leading to renal failure, and radiological imaging examination is recommended for patients with abnormal ultrasound examination to identify NC. AGXT gene detection is important for the diagnosis and treatment of PH1 in children.