Clinical features and mutational spectrum of Chinese patients with primary hyperoxaluria type 2.

Primary hyperoxaluria type 2 (PH2) is a rare hereditary disease that causes nephrolithiasis, nephrocalcinosis and kidney failure. This study aimed to investigate the clinical features and mutational spectrum of Chinese patients with PH2. A retrospective cohort study was performed on PH2 patients admitted to our center over seven years. We also systematically reviewed all the articles on Chinese PH2 patients published from January 2000 to May 2023 and conducted a meta-analysis. A total of 25 PH2 patients (10 from our center and 15 from published studies) were included in this study. The median age of onset in patients from our center was 8.50 (1.00, 24.00) years, and 50% were male. Among the full cohort of 25 Chinese patients, the median age of onset was 8.00 (0.40, 26.00) years, and 64% of them were male. Seven patients progressed to end-stage kidney disease, with a median age of 27.50 (12, 31) years. The cumulative renal survival rates were 100%, 91.67%, 45.83% and 30.56% at 10, 20, 30 and 40 years of age, respectively. A total of 18 different variants were identified, and c.864_865del was the dominant variant, accounting for 57.69% of the total alleles. Patients who were heterozygous for c.864_865del were more susceptible to nephrocalcinosis than those who were homozygous for c.864_865del and those harboring other mutations (83.33% versus 33.3% and 0%, respectively) (p = 0.025). The clinical features and mutational spectrum of Chinese PH2 patients were described. This study helps to expand awareness of the phenotypes and genotypes of Chinese PH2 patients and contributes to the improvement of diagnostic and treatment strategies for PH2 patients.

Comprehensive evaluation of patients with primary hyperoxaluria type 1: A nationwide study.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is characterized by increased endogenous oxalate production and deposition as calcium oxalate crystals. The main manifestations are nephrocalcinosis/nephrolithiasis, causing impaired kidney function. We aimed to evaluate the clinical characteristics and overall outcomes of paediatric PH1 patients in Turkey. METHODS: This is a nationwide, multicentre, retrospective study evaluating all available paediatric PH1 patients from 15 different paediatric nephrology centres in Turkey. Detailed patient data was collected which included demographic, clinical and laboratory features. Patients were classified according to their age and characteristics at presentation: patients presenting in the first year of life with nephrocalcinosis/nephrolithiasis (infantile oxalosis, Group 1), cases with recurrent nephrolithiasis diagnosed during childhood (childhood-onset PH1, Group 2), and asymptomatic children diagnosed with family screening (Group 3). RESULTS: Forty-eight patients had a mutation consistent with PH1. The most common mutation was c.971_972delTG (25%). Infantile oxalosis patients had more advanced chronic kidney disease (CKD) or kidney failure necessitating dialysis (76.9% vs. 45.5%). These patients had much worse clinical course and mortality rates seemed to be higher (23.1% vs. 13.6%). Patients with fatal outcomes were the ones with significant comorbidities, especially with cardiovascular involvement. Patients in Group 3 were followed with better outcomes, with no kidney failure or mortality. CONCLUSION: PH1 is not an isolated kidney disease but a systemic disease. Family screening helps to preserve kidney function and prevent systemic complications. Despite all efforts made with traditional treatment methods including transplantation, our results show devastating outcomes or mortality.

Renal complications in chronic hypoparathyroidism - a systematic cross-sectional assessment.

Context: Although renal long-term complications are acknowledged in chronic hypoparathyroidism (HPT), standardized investigations are scarce. Objective: To systematically investigate renal complications and their predictors in hypoparathyroid patients compared to matched individuals. Design: Prospective observational study in 161 patients with chronic HPT. Methods: Patients received renal ultrasound, clinical and laboratory assessments. An individual 1:3 matching with participants from the German population-based Study of Health in Pomerania was performed. Results: Of 161 patients (92% postoperative HPT), prevalence of eGFR <60ml/min/1.73m2 was 21%, hypercalciuria 41%. Compared to healthy individuals, HPT patients had a significantly lower eGFR (74.2 vs. 95.7 ml/min/1.73m², p<0.01). Renal ultrasound revealed calcifications in 10% (nephrocalcinosis in 7% and calculi in 3%). Patients with renal calcifications had higher levels of 24-hour urine calcium excretion (8.34 vs. 5.08 mmol/d, p=0.02), spot urine calcium excretion (4.57 vs. 2.01 mmol/L, p=0.01) and urine calcium-to-creatinine ratio (0.25 vs. 0.16, p<0.01) than patients without calcifications. Albumin-corrected calcium, phosphate, calcium-phosphate product, 25-hydroxyvitamin D in serum, eGFR, daily calcium intake or disease duration were not significantly different between these two groups. Including patients receiving rhPTH therapy, a lower serum phosphate concentration (odds ratio 1.364 [95% confidence interval (CI) 1.049-1.776], p<0.05) and a longer disease duration of HPT (odds ratio 1.063 [95% CI 1.021-1.106], p<0.01) were significant predictors for renal calcifications. Excluding patients receiving rhPTH therapy, a higher 24-hour urine calcium excretion (odds ratio 1.215 [95% CI 1.058-1.396], p<0.01) was a significant predictor for renal calcifications but not serum magnesium or disease duration. Conclusions: Prevalence of impaired renal function among patients with chronic HPT is increased and independent from visible renal calcifications. Depending on exclusion of patients with rhPTH therapy, regression analysis revealed disease duration and serum phosphate or disease duration and 24-hour urinary calcium excretion as predictors for renal calcifications. Clin Trials Identifier: NCT05585593.

Etiology and prognosis of nephrocalcinosis according to gestational age in Korean children.

BACKGROUND: Nephrocalcinosis (NC) is defined as deposition of calcium in renal tubules and interstitium and is highly related with prematurity and monogenic diseases. Recent studies have reported that NC might be a specific finding of underlying hereditary renal diseases. This study evaluated the risk factors, underlying monogenic causes, and clinical outcomes of NC in Korean children according to gestational age (GA). METHODS: A total of 464 patients younger than 18 years who were diagnosed with NC by ultrasonography from January 2013 to December 2022 in Samsung Medical Center were enrolled. Medical record data of sex, GA, birth weight, underlying disease, medication history, ultrasonography and genetic analysis were reviewed retrospectively. RESULTS: The male to female ratio was 1:0.98, and the mean age at first diagnosis of NC was 385 days. Approximately 62% of patients experienced confirmed resolution of NC after about one year. In comparison of the preterm (mean GA 28 weeks and 2 days) and full-term (mean GA 38 weeks and 2 days) groups, bronchopulmonary dysplasia, patent ductus arteriosus, and use of furosemide and vitamin D were more frequent in the preterm group. In the full-term group, a larger proportion of cases showed persistent NC without resolution and chronic kidney disease (CKD). Genetic analyses were performed in 56 patients, and the monogenic mutation rate was significantly higher in full-term children (OR 10.02, 95% CI [2.464-40.786], p = 0.001). CONCLUSION: While the overall outcomes of pediatric NC are favorable, underlying monogenic causes should be studied, especially in full-term patients without known clinical risk factors.

Nephrocalcinosis in juvenile farmed Atlantic Salmon (Salmo salar) may be linked to osmoregulatory stress.

Nephrocalcinosis is a widespread challenge in intensive production of salmon smolt. There is however no consensus on its aetiology, which makes it problematic to implement proper measures to limit its development. We performed a survey of nephrocalcinosis prevalence and environmental factors in 11 different hatcheries in Mid-Norway as well as a 6-month monitoring in one of the hatcheries. A multivariate analysis indicated that the most influencing factor for the prevalence of nephrocalcinosis was the supplementation of sea water during smolt production. In the 6-month monitoring, the hatchery introduced salinity in the production water prior to the change in day length. Mismatch in those environmental signals may increase the risk for developing nephrocalcinosis. Salinity fluctuations prior to smoltification can cause osmotic stress and result in unbalanced levels of ions in fish blood. This was clearly illustrated in our study, as the fish experienced chronic hypercalcaemia and hypermagnesaemia. Both magnesium and calcium are excreted over the kidneys and it is possible that their prolonged, elevated levels in plasma resulted in an oversaturation of the urine when finally excreted. This again could have led to the aggregation of calcium deposits within the kidney. This study indicates a relationship between osmotic stress induced by salinity changes in juvenile Atlantic salmon and the development of nephrocalcinosis. Other factors that may affect the severity of nephrocalcinosis are currently subjects for discussion.

Diagnostic policies on nephrolithiasis/nephrocalcinosis of possible genetic origin by Italian nephrologists: a survey by the Italian Society of Nephrology with an emphasis on primary hyperoxaluria.

BACKGROUND: Primary hyperoxaluria is a genetic disorder of the metabolism of glyoxylate, the precursor of oxalate. It is characterized by high endogenous production and excessive urinary excretion of oxalate, resulting in the development of calcium oxalate nephrolithiasis, nephrocalcinosis, and, in severe cases, end-stage kidney disease and systemic oxalosis. Three different forms of primary hyperoxaluria are currently known, each characterized by a specific enzymatic defect: type 1 (PH1), type 2 (PH2), and type 3 (PH3). According to currently available epidemiological data, PH1 is by far the most common form (about 80% of cases), and is caused by a deficiency of the hepatic enzyme alanine:glyoxylate aminotransferase. METHODS: A survey on rare forms of nephrolithiasis and nephrocalcinosis with a focus on primary hyperoxaluria in the setting of Italian Nephrology and Dialysis Centers, using an online questionnaire, was recently conducted by the Project Group "Rare Forms of Nephrolithiasis and Nephrocalcinosis" of the Italian Society of Nephrology, with the aim of assessing the impact and management of this disorder in clinical practice in Italy. RESULTS: Forty-five public and private Italian Centers participated in the survey, and responses to the questionnaire were provided by 54 medical professionals. The survey results indicate that 21 out of the 45 participating Centers are managing or have managed primary hyperoxaluria patients, most of whom are on dialysis, or are recipients of kidney transplants. CONCLUSIONS: The data of this survey indicate the need to implement genetic testing in suspected cases of primary hyperoxaluria, not only in the setting of dialysis or transplantation, but also with the aim of encouraging early diagnosis of PH1, which is the only type of primary hyperoxaluria for which specific drug therapy is currently available.

Clinical and molecular characterization of a large primary hyperoxaluria cohort from Saudi Arabia: a retrospective study.

BACKGROUND: Primary hyperoxalurias (PHs) constitute rare disorders resulting in abnormal glyoxalate metabolism. PH-associated phenotypes range from progressive nephrocalcinosis and/or recurrent urolithiasis to early kidney failure. METHODS: A retrospective study was conducted for patients with confirmed PH diagnoses from three tertiary centers in Saudi Arabia. Detailed clinical molecular diagnosis was performed for 25 affected individuals. Whole exome sequencing (WES)-based molecular diagnosis was performed for all affected individuals. RESULTS: The male:female ratio was 52% male (n = 13) and 48% female (n = 12), and consanguinity was present in 88%. Nephrolithiasis and/or nephrocalcinosis were present in all patients. Kidney stones were present in 72%, nephrocalcinosis in 60%, hematuria in 32%, proteinuria in 16%, abdominal pain in 36%, developmental delay in 8%, and chronic kidney disease stage 5 (CKD stage 5) was observed in 28% of the patients. The most common PH disorder was type I caused by variants in the AGXT gene, accounting for 56%. The GRHPR gene variants were identified in 4 patients, 16% of the total cases. Seven patients did not reveal any associated variants. Missense variants were the most commonly observed variants (48%), followed by frame-shift duplication variants (28%). CONCLUSIONS: Characterization of the genetic and clinical aspects of PH in this unique population provides direction for improved patient management and further research. A higher resolution version of the Graphical abstract is available as Supplementary information.

Genotype-Phenotype correlation of distal renal tubular acidosis in Tunisia.

INTRODUCTION: Distal renal tubular acidosis (dRTA) is a rare genetic disorder due to the incapacity of the α intercalated cells to excrete protons in the collecting duct. This impaired distal acidification of urine leads to a chronic hyperchloremic metabolic acidosis with a normal plasma anion gap, hypokalemia, and hypercalciuria with hypocitraturia causing nephrocalcinosis. Primary dRTA is inherited either as an autosomal dominant (SLC1A4 gene) or autosomal recessive trait (ATP6V0A1/ATP6V1B1 genes). AIM: To analyze the genotype-phenotype correlation of dTA in Tunisia. METHODS: In this study we present all available data of patients followed in our center for dRTA over the last 28 years and who had a genetic study. This was a retrospective descriptive study from January 1991 to December 2018, conducted in the Pediatrics Department of the Charles Nicolle Hospital in Tunis. RESULTS: Twenty-five cases of dRTA were collected and were offered genetic analysis to confirm the diagnosis. The molecular mutation was confirmed in 13 patients of whom 11 had homozygous mutations in ATP6V1B1(G1) and 2 had homozygous mutations in ATP6V0A4(G2). Median age of diagnosis was 8.9 months. Severe growth retardation was documented in nine children with mutations in ATP6V1B1, in eight children with no genetic mutation and in the two patients with a mutation in ATP6V0A4. All children were found to have metabolic acidosis at initial presentation. Hypokalemia was found in 19 children. All patients were polyuric. Twenty-two patients had nephrocalcinosis (88%). The treatment was based on alkali prescription and substitution of potassium chloride. Sensorineural hearing loss (SNHL) was documented in 12 children. At the last consultation, 14 patients had chronic kidney disease (CKD) stage 2 or higher, 8 of whom were in the group with negative genetic analysis. CONCLUSION: According to the early onset in patients, the recessive mode seems to be the mode of transmission in Tunisia. dRTA was long considered to not affect renal function, but we note a decline in eDFG.

[Epidemiological, clinical and evolutionary particularities of primary distal tubular acidosis in Tunisian children]. / Particularités épidémiologiques, cliniques et évolutives de l'acidose tubulaire distale primitive chez l'enfant tunisien.

INTRODUCTION: The distal renal tubular acidosis of children is characterized by hyperchloremic metabolic acidosis with normal anion gap, hypokalemia, hypercalciuria and nephrocalcinosis. It is secondary to the inability of alpha intercalar cells of the distal tubule to acidify urine of genetic origin. OBJECTIVE: To analyse the epidemiological aspects of distal tubular acidosis in Tunisia and study its evolutionary profile. PATIENTS AND METHODS: We conducted a retrospective descriptive study involving 44 patients followed at the paediatrics department of the Charles Nicolle Hospital in Tunis for 28 years (1991-2018). RESULTS: The most common discovery circumstances were growth retardation (88.6%), dehydration (56.8%), ployuro-polydipsic syndrome (47.7%), vomiting (40.9%) and nephrocalcinosis (38.6%). Growth retardation was found in 52.3% of patients. Dehydration was diagnosed in 59.1% of patients on the first exam. Polyuria was constant with an average diuresis of 8 cc/kg/h. All patients had the complete form of distal renal tubular acidosis with an average alkaline reserve of 11.1 mmol/L. Nephocalcinosis was found in 77.3% associated with nepholithiasis in 22.7%. Twenty-four patients had sensorineural deafness, nine of whom had ATP6V1B1/2p13 mutation. The ATP6V0A4/7q33-34 mutation was present in two patients. We used a high alkaline treatment dose with an average maintenance dose of 8.17 mmol/kg/24 hours. In the long term, stunting persisted in 34% of patients. The mean of creatinine's clearance at the last evaluation was 89.38 mL/min/1.73 m2 SC with stage 2 of chronic kidney disease in 50% of patients. CONCLUSION: Distal renal tubular acidosis has long been considered a benign pathology but is responsible for a progressive decline in GFD. Adequate metabolic control is needed to stabilize kidney function.

Primary hyperoxaluria and genetic linkages: an insight into the disease burden from Pakistan.

Autosomal recessive disorders are prevalent in Pakistan, a developing South Asian country where consanguineous marriages are common. This study seeks to determine the prevalence of monogenic causes in children presenting with nephrocalcinosis and nephrolithiasis at a dialysis and transplant center in Karachi, Pakistan. A retrospective analysis was conducted in children aged 1-18 years presenting with nephrocalcinosis, between 2010 and 2019. Demographic information, clinical profile, laboratory parameters and stone analysis were collected, on a pre-designed questionnaire. One hundred and twenty-six children were included, with 11 and 3 diagnosed with renal tubular acidosis and Bartter's syndrome respectively. Next-generation sequencing and Sanger sequencing was performed on 112 children. Eighty-seven patients were diagnosed with primary hyperoxaluria, with mutations in alanine-glyoxylate-aminotransferase gene found in 73, followed by glyoxylate reductase/hydroxy-pyruvate reductase in 13, and 4-hydroxy-2-oxaloglutarate aldolase in 1. Twenty-five patients reported negative for mutations. Sixty-four percent were males, with a statistically significant difference (p < 0.05). History of parental consanguineous marriage was found in 98% of the cohort. Fifty-four and 40 patients presented to the clinic with Chronic Kidney Disease Stage 1 and Stage 5, respectively, with a statistically significant difference p = 0.007. Mutations noted in our cohort are different and more severe than those reported in the developed world. The disease poses a major disease burden in developing world context with the only treatment option of combined liver-kidney transplantation not available in Pakistan.

Nephrocalcinosis in very low birth weight infants: incidence, associated factors, and natural course.

BACKGROUND: Preterm kidney is exposed to various exogenous factors that may impact its function such as nephrotoxic drugs or nephrocalcinosis. We investigated prevalence and risk factors of nephrocalcinosis (NC) in recently born very low birth weight (VLBW) infants submitted to improved biological monitoring. METHODS: Retrospective, case-control study in very preterm infants (< 32 + 6 weeks, ≤ 1500 g) admitted to a tertiary care unit during a 6-year period. Each case (ultrasound-diagnosed NC) was matched with two controls (no NC). Data were collected at days 15 and 30 of life and 35 weeks corrected age, with follow-up at 18 months and 3 years. RESULTS: Of 525 eligible infants, overall prevalence of NC was 17.1% at 35 weeks corrected age. Prevalence was halved between 2012 (26.1%) and 2017 (11.8%). We included 265 infants, more than half being born before 28 weeks. Cases presented with more severe morbidity than controls, but reached statistical significance only in infants born < 28 weeks (88.2% vs. 68.3%, P = 0.01). Protein, energy, calcium, phosphorus, and vitamin D intakes were similar in the two groups and did not change significantly over the study period. Weight gain was similar in the two groups. Exposure to furosemide (OR [IC95%]: 1.26 [1.02; 1.57]) and postnatal growth (1.65 [1.04; 2.67]) were independent risk factors of NC. NC resolved 12-18 months after diagnosis in 61% of infants. CONCLUSION: Prevalence of NC is significant but can be reduced. Furosemide should be cautiously prescribed in VLBW infants, and nutritional support must be well monitored to support postnatal growth and limit risk of nephrocalcinosis. TRIAL REGISTRATION: ClinicalTrials.gov: NCT 04,860,583. A higher resolution version of the Graphical abstract is available as Supplementary information.

Childhood nephrolithiasis and nephrocalcinosis caused by metabolic diseases and renal tubulopathy: A retrospective study from 2 tertiary centers.

OBJECTIVES: To study childhood nephrolithiasis and nephrocalcinosis caused by metabolic disorders, distal renal tubular acidosis (dRTA), and familial hypomagnesemia, hypercalciuria, and nephrocalcinosis (FHHNC). METHODS: We retrospectively evaluated 86 children presented over 10 years (2011-2021), with nephrolithiasis (89%) and nephrocalcinosis (11%) caused by metabolic disorders (62%), FHHNC (21%), and dRTA (17%). RESULTS: The mean age at discovery was 72.7 months. The underlying metabolic etiologies included hyperoxaluria (38%), cystinuria (32%), hypercalciuria (24%), and hyperuricosuria (6%). Genetic testing was carried out for 23 patients. Hyperoxaluria was typically treated medically (75%). However, the majority progressed to end-stage kidney disease (ESKD). Most children with cystinuria, hypercalciuria, and hyperuricosuria required medical and surgical intervention. Patients with FHHNC typically presented with nephrocalcinosis. Genetic testing revealed Claudin-16 mutations in 7 children. Patients often progressed to stage II-IV chronic kidney disease (61%) and ESKD (6%). Patients with dRTA typically presented with nephrocalcinosis (80%), as well as poor weight gain and failure to thrive (86%), and medical treatment included sodium bicarbonate and potassium replacement. Despite nephrocalcinosis progression, most patients had normal renal function (53%), although the remaining 47% progressed to chronic kidney disease (none reached ESKD). CONCLUSION: Childhood nephrolithiasis is mainly related to metabolic disorders and is associated with poor renal outcomes. Nephrocalcinosis and nephrolithiasis have poor outcomes when associated with FHHNC, while nephrocalcinosis associated with dRTA has relatively good renal outcomes.

A nationwide retrospective study in Turkish children with nephrocalcinosis.

BACKGROUND: Nephrocalcinosis (NC) is defined as calcium deposition in the kidney parenchyma and tubules. This study aims to determine the etiology, risk factors, and follow-up results of patients with NC in Turkey. METHODS: Patients diagnosed with NC in the pediatric nephrology Department Units of 19 centers from all geographical regions of Turkey over a 10-year period (2010-2019) were included in the study. The medical records from the centers were reviewed and demographic data, admission complaints, medical history, systemic and genetic disorders, risk factors for NC, treatment details, and presence of NC after one-year follow-up, were recorded retrospectively. RESULTS: The study sample included 195 patients (88 females, 107 males). The mean age at diagnosis was 39.44 ± 47.25 (0.5-208) months; 82/190 patients (43.2%) were diagnosed incidentally; 46/195 patients (23.6%) had an underlying disease; idiopathic hypercalciuria was detected in 75/195 (38.4%) patients. The most common systemic diseases were distal renal tubular acidosis in 11/46 patients (23.9%), primary hyperoxaluria in 9/46 patients (19.6%) and Bartter syndrome in 7/46 patients (15.3%). After one year of follow-up, NC resolved in 56/159 patients (35.2%) and they all did not have an underlying systemic disease. DISCUSSION: The most common presentation of NC was incidental. Distal renal tubular acidosis and primary hyperoxaluria were the main systemic diseases leading to NC, while hypercalciuria was the most common metabolic risk factor. Nephrocalcinosis was found to remain in most of the patients at a one-year follow-up. It may resolve particularly in patients with no underlying systemic disease.

Incidence of Complications in 25 Adult Patients With X-linked Hypophosphatemia.

CONTEXT: Adults with X-linked hypophosphatemia (XLH) present complications other than osteomalacia. OBJECTIVE: To describe the incidence and severity of comorbidities in adults with XLH. METHODS: This observational retrospective study included a total of 25 adults with XLH with thorough investigations, including spinal computed tomography scans, x-rays of hip/knee joints and Achilles tendons, abdominal ultrasounds, and audiograms. The index of ossification of the anterior/posterior longitudinal ligament and yellow ligament (OA/OP/OY index) and the sum of OA/OP/OY index (OS index) were utilized to evaluate the severity of spinal ligament ossification. The Kellgren-Lawrence (KL) classification was adopted to evaluate the severity of the hip/knee osteophytes. RESULTS: The participants consisted of 13 male patients and 12 female patients from 21 families, with a median age of 43 (range, 18-72) years. In all, 20 patients (80%) showed spinal ligament ossification. The median OA/OP/OY/OS indices were 2 (0-22), 0 (0-15), 6 (0-13), and 12 (0-41), respectively. Hip/knee osteophytes were reported in 24 (96%) and 17 cases (68%). The median KL grade was 3 in the hip joint and 2 in the knee joint, and 18 cases (72%) developed enthesopathy in the Achilles tendon. Nephrocalcinosis and hearing impairment were observed in 18 (72%) and 8 (32%) cases. CONCLUSION: This study revealed a high prevalence and severity of ectopic ossification and disclosed the incidence of nephrocalcinosis and hearing impairment in adults with XLH. In cases with severe spinal ligament ossification or noticeable osteophytes around the hip/knee joints, undiagnosed XLH should be considered as a possible underlying condition.

Clinical analysis of 13 children with primary hyperoxaluria type 1.

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.

Risk of Nephrolithiasis and Nephrocalcinosis in Patients with Chronic Hypoparathyroidism: A Retrospective Cohort Study.

INTRODUCTION: Chronic hypoparathyroidism managed with conventional treatment, comprising oral administration of calcium and active vitamin D, has been associated with renal complications, including nephrolithiasis and nephrocalcinosis. Further larger-scale studies are needed to examine these risks. This study evaluated the risk of nephrolithiasis and nephrocalcinosis in patients with chronic hypoparathyroidism. METHODS: A retrospective cohort study using a managed care claims database in the United States from January 2007 to June 2017. Included patients were those with chronic hypoparathyroidism (excluding those receiving parathyroid hormone) and randomly selected patients without hypoparathyroidism over a maximum of 5-year follow-up. The main outcome measures were nephrolithiasis, identified by diagnosis codes or procedure codes for removing kidney stones, and nephrocalcinosis, identified by diagnosis codes. RESULTS: The nephrolithiasis analyses included 8097 adult patients with hypoparathyroidism and 40,485 adult patients without hypoparathyroidism. After excluding patients with a diagnosis of nephrocalcinosis at baseline, nephrocalcinosis analyses included 8051 patients with hypoparathyroidism and 40,466 patients without hypoparathyroidism. During 5 years of follow-up, patients with chronic hypoparathyroidism had significantly increased risk of nephrolithiasis and nephrocalcinosis in Kaplan-Meier analysis compared with patients without hypoparathyroidism (both P < 0.001). In the adjusted analyses, chronic hypoparathyroidism was associated with higher risks of nephrolithiasis (hazard ratio [HR], 1.81; 95% confidence interval [CI] 1.60-2.04) and nephrocalcinosis (HR, 6.94; 95% CI 4.41-10.92). A sensitivity analysis restricted to patients with at least one kidney imaging examination showed that 2.6% of patients (n = 59) with hypoparathyroidism and 0.5% of patients (n = 20) without hypoparathyroidism (ratio, 5.5; P < 0.001) developed nephrocalcinosis. CONCLUSIONS: This large retrospective cohort study showed a statistically significant and clinically meaningful increased risk of nephrolithiasis and nephrocalcinosis in patients who have chronic hypoparathyroidism compared with those who do not have chronic hypoparathyroidism.

[Nephrocalcinosis in children]. / Néphrocalcinose de l'enfant.

Nephrocalcinosis is defined by calcium phosphate or calcium oxalate deposits in the kidney parenchyma, particularly in tubular epithelial cells and interstitial tissue. It should be differentiated from urolithiasis where calcium salts deposits are located in the kidney and urinary tract. The epidemiology of nephrocalcinosis in children is unknown but the condition is not so rare, with an increased incidence in preterm infants. Often detected as an incidental finding, nephrocalcinosis may be classified according to the radiological type: medullary, cortical or diffuse. Nephrocalcinosis in children can be caused by a variety of etiology. The most common causes concern medullary nephrocalcinosis and include hereditary tubular disorders, in particular distal renal tubular acidosis and Dent disease, metabolic disorders such as idiopathic hypercalciuria and hyperoxaluria, and iatrogenic causes such as vitamin D intoxication. In the newborn, the main cause is hypercalciuria of the premature baby, whose multifactorial origin is largely iatrogenic. Primary hyperoxaluria which can lead to early onset nephrocalcinosis and usually to chronic kidney disease should always be considered and further investigated. In order to provide a specific diagnosis, it is essential to take into account the family history, the clinical context and complete laboratory data. Early initiation of an appropriate etiological treatment is recommended and may prevent or delay the progression to chronic kidney disease in some cases.

Hypercalcemia in Children Using the Ketogenic Diet: A Multicenter Study.

CONTEXT: The ketogenic diet is associated with progressive skeletal demineralization, hypercalciuria, and nephrolithiasis. Acute hypercalcemia has been described as a newly recognized complication of this treatment. OBJECTIVE: To describe the clinical characteristics of acute hypercalcemia in children on the ketogenic diet through analysis of the presentation, response to treatment, and natural history in a large cohort of patients. DESIGN: A multicenter case series was performed including children who developed acute hypercalcemia while treated with the ketogenic diet. Information on clinical presentation, treatment, and course of this complication was collated centrally. RESULTS: There were 14 patients (median (range) age 6.3 (0.9 to 18) years) who developed hypercalcemia 2.1 (range, 0.2-12) years after starting the ketogenic diet. All had low levels of parathyroid hormone and levels of 1,25-dihydroxyvitamin D were low in all except one. Seven (50%) had impaired renal function at presentation. All except the 2 oldest had low alkaline phosphatase levels for age. Once normocalcemia was achieved, hypercalcemia recurred in only 2 of these patients over observation of up to 9.8 years. One patient discontinued the ketogenic diet prior to achieving normocalcemia while 4 more stopped the diet during follow-up after resolution of hypercalcemia. CONCLUSIONS: Ketotic hypercalcemia can occur years after starting the ketogenic diet, especially in the setting of renal impairment. The mechanism is unknown but appears to be due to reduced osteoblast activity and impaired bone formation. We recommend close attention to optimizing bone health in these children, and screening for the development of ketotic hypercalcemia.

Effects of bodybuilding supplements on the kidney: A population-based incidence study of biopsy pathology and clinical characteristics among middle eastern men.

BACKGROUND: The incidence of kidney diseases among bodybuilders is unknown. METHODS: Between January 2011 and December 2019, the Iraqi Kurdistan 15 to 39 year old male population averaged 1,100,000 with approximately 56,000 total participants and 25,000 regular participants (those training more than 1 year). Annual age specific incidence rates (ASIR) with (95% confidence intervals) per 100,000 bodybuilders were compared with the general age-matched male population. RESULTS: Fifteen male participants had kidney biopsies. Among regular participants, diagnoses were: focal segmental glomerulosclerosis (FSGS), 2; membranous glomerulonephritis (MGN), 2; post-infectious glomeruonephritis (PIGN), 1; tubulointerstitial nephritis (TIN), 1; and nephrocalcinosis, 2. Acute tubular necrosis (ATN) was diagnosed in 5 regular participants and 2 participants training less than 1 year. Among regular participants, anabolic steroid use was self-reported in 26% and veterinary grade vitamin D injections in 2.6%. ASIR for FSGS, MGN, PIGN, and TIN among regular participants was not statistically different than the general population. ASIR of FSGS adjusted for anabolic steroid use was 3.4 (- 1.3 to 8.1), a rate overlapping with FSGS in the general population at 2.0 (1.2 to 2.8). ATN presented as exertional muscle injury with myoglobinuria among new participants. Nevertheless, ASIR for ATN among total participants at 1.4 (0.4 to 2.4) was not significantly different than for the general population at 0.3 (0.1 to 0.5). Nephrocalcinosis was only diagnosed among bodybuilders at a 9-year cumulative rate of one per 314 vitamin D injectors. CONCLUSIONS: Kidney disease rates among bodybuilders were not significantly different than for the general population, except for nephrocalcinosis that was caused by injections of veterinary grade vitamin D compounds.

Laboratory changes during adrenocorticotropic hormone therapy associated with renal calcified lesions.

BACKGROUND: Renal calcified lesions are known as one of the complications during adrenocorticotropic hormone (ACTH) therapy for intractable epilepsy. However, laboratory changes during the therapy or laboratory features of high-risk cases with renal calcified lesions are yet to be clarified. METHODS: In this study, 43 patients with West syndrome aged ≤2 years were included. We retrospectively reviewed age and body mass index at the beginning of ACTH therapy, as well as the amount of fluid intake, daily urinary volume, and laboratory data during therapy. In addition, we studied the urinary sediment of the cases with renal calcified lesions diagnosed by computed tomography. RESULTS: After initiating ACTH treatment, urinary calcium (Ca)/creatinine ratio and urinary pH increased within 2 weeks. Urinary crystals and renal tubular epithelial cells (RTECs) in urinary sediment were frequently found in most cases. Urinary Ca levels, proteinuria or frequency of urinary crystals, and number of RTECs in the urinary sediment were significantly higher in patients with epithelial casts (ECs) or hematuria than in patients without these findings. Among the seven patients who underwent abdominal CT, ECs or hematuria were found only in those with renal calcified lesions. These findings suggested that patients with ECs or hematuria were more likely to have calcified lesions. CONCLUSIONS: The risk of renal calcified lesions increased after 2 weeks of ACTH treatment. Abnormal findings in urinary sediments might be an early sign of renal calcification during ACTH therapy.