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.

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.

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.

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.

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.

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.

A long-term clinical study on individuals with amelogenesis imperfecta.

BACKGROUND: The aims of this study are to present sociodemographic and familial characteristics, clinical and systemic findings, dental treatment needs, and concomitant dental anomalies in patients with amelogenesis imperfecta (AI) and to evaluate time-varying conditions in these long-term follow-up patients. MATERIALS AND METHODS: Records of patients with AI who were examined in the Department of Pediatric Dentistry between 1999 and 2017 were reviewed. Information about sociodemographic characteristics, history of AI and consanguinity in family, systemic conditions, reasons for referral to the clinic, oral hygiene habits and gingival health, occlusion findings, and performed treatments were gathered. Dental anomalies in radiographs were also evaluated. Baseline and final situations of the patients were assessed. Statistical analyses were performed. RESULTS: Of 75 patients aged 3-15 years with follow-ups up to 12 years, 34 had AI in their families and 15 were born from consanguineous marriages. Nephrocalcinosis has been observed in 5 patients. Main reasons for referral to the clinic were related to esthetic and hypersensitivity concerns. Twenty-two patients had gingivitis, and during follow-up process, gingival problems could not be completely prevented due to poor oral hygiene habits. Vertical dimension loss, open-bite, and cross-bite were seen in 16, 15, and 10 patients, respectively. Of the patients, 63% experienced restorative, 33% stainless steel crown, 17% endodontic, 8% prosthetic treatments, and 24% had retreatment needs. Concomitant dental anomalies were dens invaginatus, taurodontism, ectopic eruption, delayed eruption, hypodontia, and pulpal calcification. CONCLUSION: Early diagnosis and interventions considering the time-varying conditions with long-term follow-ups provide significant improvements in clinical maintenance of patients with AI.

Whole exome sequencing frequently detects a monogenic cause in early onset nephrolithiasis and nephrocalcinosis.

The incidence of nephrolithiasis continues to rise. Previously, we showed that a monogenic cause could be detected in 11.4% of individuals with adult-onset nephrolithiasis or nephrocalcinosis and in 16.7-20.8% of individuals with onset before 18 years of age, using gene panel sequencing of 30 genes known to cause nephrolithiasis/nephrocalcinosis. To overcome the limitations of panel sequencing, we utilized whole exome sequencing in 51 families, who presented before age 25 years with at least one renal stone or with a renal ultrasound finding of nephrocalcinosis to identify the underlying molecular genetic cause of disease. In 15 of 51 families, we detected a monogenic causative mutation by whole exome sequencing. A mutation in seven recessive genes (AGXT, ATP6V1B1, CLDN16, CLDN19, GRHPR, SLC3A1, SLC12A1), in one dominant gene (SLC9A3R1), and in one gene (SLC34A1) with both recessive and dominant inheritance was detected. Seven of the 19 different mutations were not previously described as disease-causing. In one family, a causative mutation in one of 117 genes that may represent phenocopies of nephrolithiasis-causing genes was detected. In nine of 15 families, the genetic diagnosis may have specific implications for stone management and prevention. Several factors that correlated with the higher detection rate in our cohort were younger age at onset of nephrolithiasis/nephrocalcinosis, presence of multiple affected members in a family, and presence of consanguinity. Thus, we established whole exome sequencing as an efficient approach toward a molecular genetic diagnosis in individuals with nephrolithiasis/nephrocalcinosis who manifest before age 25 years.

Prevalence of Nephrocalcinosis in Pseudohypoparathyroidism: Is Screening Necessary?

The prevalence of nephrocalcinosis in persons with pseudohypoparathyroidism has not been systematically examined. We conducted a retrospective study of renal imaging and biochemical results in 19 patients with pseudohypoparathyroidism with 49 imaging assessments. No cases of nephrocalcinosis were identified. Routine screening for nephrocalcinosis in pseudohypoparathyroidism may not be necessary.

Long-term renal outcome in children with OCRL mutations: retrospective analysis of a large international cohort.

Background: Lowe syndrome (LS) and Dent-2 disease (DD2) are disorders associated with mutations in the OCRL gene and characterized by progressive chronic kidney disease (CKD). Here, we aimed to investigate the long-term renal outcome and identify potential determinants of CKD and its progression in children with these tubulopathies. Methods: Retrospective analyses were conducted of clinical and genetic data in a cohort of 106 boys (LS: 88 and DD2: 18). For genotype-phenotype analysis, we grouped mutations according to their type and localization. To investigate progression of CKD we used survival analysis by Kaplan-Meier method using stage 3 CKD as the end-point. Results: Median estimated glomerular filtration rate (eGFR) was lower in the LS group compared with DD2 (58.8 versus 87.4 mL/min/1.73 m2, P < 0.01). CKD stage II-V was found in 82% of patients, of these 58% and 28% had moderate-to-severe CKD in LS and DD2, respectively. Three patients (3%), all with LS, developed stage 5 of CKD. Survival analysis showed that LS was also associated with a faster CKD progression than DD2 (P < 0.01). On multivariate analysis, eGFR was dependent only on age (b = -0.46, P < 0.001). Localization, but not type of mutations, tended to correlate with eGFR. There was also no significant association between presence of nephrocalcinosis, hypercalciuria, proteinuria and number of adverse clinical events and CKD. Conclusions: CKD is commonly found in children with OCRL mutations. CKD progression was strongly related to the underlying diagnosis but did not associate with clinical parameters, such as nephrocalcinosis or proteinuria.

Congenital and acquired diseases related to stone formation.

PURPOSE OF REVIEW: To summarize the latest findings of congenital and acquired diseases related to stone formation and help understanding the multitude of cofactors related to urolithiasis. RECENT FINDINGS: Urolithiasis is related to a broad spectrum of congenital and acquired diseases and its management varies according to the stone type, underlying disease or recurrence rate, but it also changes according to recent findings and developments. As prevalence of urolithiasis is constantly increasing, identification of high-risk stone formers and early treatment is essential. Therefore, genetic evaluation like whole exome sequencing becomes a pertinent part of further diagnostics. SUMMARY: Stone formation is a very heterogeneous pathomechanism. This prompt us to look at every patient individually particularly in high-risk patients, including stone and 24-h-urine analysis and additional diagnostic work-up based on stone type or underlying disease.

Focal segmental glomerulosclerosis and medullary nephrocalcinosis in children with ADCK4 mutations.

BACKGROUND: Mutations in the AarF domain containing kinase 4 gene (ADCK4), one of the novel genes causing steroid-resistant nephrotic syndrome (SRNS), usually manifest as isolated adolescent-onset focal segmental glomerulosclerosis (FSGS). ADCK4 interacts with components of the coenzyme Q10 (CoQ10) biosynthesis pathway. METHODS: The incidence and phenotypes of patients with ADCK4 mutations were investigated in a cohort of Korean pediatric patients with SRNS. RESULTS: Among the 53 patients enrolled in the study the incidence of ADCK4-associated FSGS was 7.5% (n = 4) in children aged 5 years and older with multidrug-resistant FSGS. Two additional patients were included for phenotype analyses, one detected by family screening and the other with cyclosporine-responsive FSGS. These six patients presented proteinuria without overt nephrotic syndrome at a median age of 110 (range 60-153) months, of whom five progressed to end-stage renal disease within a median period of 46 (range 36-79) months after onset. Renal biopsies revealed mitochondrial abnormalities in podocytes and tubular cells of all patients. Notably, all patients showed accompanying medullary nephrocalcinosis. None of the patients showed other extrarenal manifestations. CONCLUSIONS: ADCK4 mutations should be considered in older children presenting with steroid resistant FSGS. An early diagnosis of ADCK4 mutations is essential because the condition is treatable with CoQ10 supplementation at an early stage. The association with medullary nephrocalcinosis may be an additional diagnostic indicator.

Hypertension is a characteristic complication of X-linked hypophosphatemia.

X-linked hypophosphatemia (XLH) is a group of rare disorders caused by defective proximal tubular reabsorption of phosphate. Mutations in the PHEX gene are responsible for the majority of cases. There are very few reports of long-term complications of XLH other than skeletal and dental diseases. The aim of this study was to identify the phenotypic presentation of XLH during adulthood including complications other than skeletal and dental diseases. The clinical and biochemical phenotype of 22 adult patients with a PHEX gene mutation were examined retrospectively from their medical records. 6 patients had hypertension. The average age of hypertension onset was 29.0 years. Secondary hyperparathyroidism preceded the development of hypertension in 5 patients. 1 patient developed tertiary hyperparathyroidism. 15 patients had nephrocalcinosis. 2 patients had chronic renal dysfunction. Patients with hypertension had a significantly lower eGFR (p=0.010) compared to patients without hypertension. No significant difference was found in any other parameters. To examine the genotype-phenotype correlation, 10 adult males were chosen for analysis. No significant genotype-phenotype correlation analysis was revealed in any of the complications. However, there was a possibility that the age at nephrocalcinosis onset was younger in the non-missense mutation group than in the missense mutation group (p=0.063). This study corroborated the view that early-onset hypertension could be one of the characteristic complications seen in XLH patients. Considering the limited number of our patients, further study is necessary to address a potential cause of hypertension. XLH patients require careful lifelong treatment.

[Clinical characteristics of adult-onset primary hypoparathyroidism: a retrospective analysis of 200 cases].

Objective: To study the clinical characteristics of primary hypoparathyroidism in adults. Methods: The clinical data of 200 cases with adult-onset primary hypoparathyroidism in Peking Union Medical College Hospital during December 1987 to December 2015 were collected and analyzed retrospectively. Among them, 128 cases were followed up for a median period of 3 years. Results: The major manifestations at their first visits were tetany and numbness in the distal extremities(81.5%, 163/200 and 62.0%, 124/200). Thirty-two percent of the cases (62 cases) had history of seizures, and 60.9%(98/161) and 74.4%(96/129) of them were with intracerebral calcifications and cataracts, respectively.Most of subjects(155/200)had more than one year delay in diagnosis. Hypercalciuria occurred in 67.2%(86/128) of the cases during the follow-up. No significant differences in the clinical characteristics and biochemical markers between the hypercalciuria subjects and the non-hypercalciuria subjects. Renal nephrocalcinosis or stones were found in 6.5%(5/77) of the cases, and kidney function decreased in 6.6%(6/91) of the patients. Kidney function was negatively associated with age and duration of disease. Conclusions: The predominant manifestations of primary hypoparathyroidism in adults included tetany and numbness in the distal extremities and seizures. It is often misdiagnosed. Calcium supplement combined with vitamin D or its metabolites effectively relieve clinical symptoms and signs. The serum and urinary calcium levels should be monitored frequently to reduce renal complications.

Revisiting nephrocalcinosis: A single-centre perspective. A northern Italian experience.

AIM: Nephrocalcinosis is a clinical-pathological entity characterized by the deposition of calcium salts within the kidney parenchyma. Both the protean presentation and multiple causes may explain the lack of data regarding its prevalence. The aim of this study is to report the prevalence and main clinical features of nephrocalcinosis diagnosed in a newly opened nephrology outpatient unit. METHODS: Analysis on the data we prospectively gathered from the start of activity (2007-2013) was carried out. Clinical and laboratory data were collected from the medical records and from the general laboratory; diagnosis was based upon imaging data reviewed by the same radiologists. RESULTS: Sixty-five of 2695 patients referred to our unit were diagnosed with nephrocalcinosis (2.4%). The affected patients were younger than the overall out-patient population (median: 37.7 (min-max: 8-82) vs 63 years (2-102) P < 0.001), with higher female prevalence (68% vs 51.4%: P < 0.05) and better preserved kidney function (CKD-EPI 103 (23-165) vs 60 mL/min (3.2-169) P < 0.001). Kidney stones were the main reason for referral (35.4%), followed by electrolyte disturbances (22.7%), acute pyelonephritis (4.6%), AKI or CKD (4.6%). Nephrocalcinosis was associated with autoimmune diseases in 29% and with microcythaemia in 23%, while positive family history was present in 23% of patients. Various electrolyte disturbances were observed, with hypercalciuria being the hallmark of beta thalassaemic patients. CONCLUSIONS: Nephrocalcinosis is a rare, but not exceptional disease in nephrology. In Mediterranean countries, microcythaemia would appear to be a major cause of this disease. Greater awareness of nephrocalcinosis is needed for an integrated approach involving various branches of internal medicine and radiology.

Posterior reversible encephalopathy syndrome (PRES) and hypomagnesemia: A frequent association?

Posterior reversible encephalopathy syndrome (PRES) is a serious neurological condition encountered in various medical fields. Pathophysiological factor(s) common to PRES cases of apparently unrelated etiologies are yet to be found. Based on the hypothesis that hypomagnesemia might participate in the cascade leading to PRES, our study sought to verify whether hypomagnesemia is frequently associated with PRES regardless of etiology. From a retrospective study of a cohort of 57 patients presenting with PRES of different etiologies, presented here are the findings of 19 patients with available serum magnesium levels (SMLs) during PRES. In the acute phase of PRES, hypomagnesemia was present in all 19 patients in spite of differences in etiology (including immunosuppressive drugs, hypertensive encephalopathy, eclampsia, systemic lupus erythematosus, iatrogenic etiology and unknown). SMLs were within normal ranges prior to PRES and below normal ranges during the first 48h of PRES, with a significant decrease in SMLs during the acute phase. In this retrospective study, constant hypomagnesemia was observed during the acute phase of PRES regardless of its etiology. These results now require larger studies to assess the particular importance of acute hypomagnesemia in PRES and especially the possible need to treat PRES with magnesium sulfate.

Nephrocalcinosis is a risk factor for kidney failure in primary hyperoxaluria.

Stone formation and nephrocalcinosis are both very common features of primary hyperoxaluria, yet the extent of each disease varies markedly between patients. Here we studied whether kidney damage from nephrocalcinosis and/or stone related events contributed to end-stage kidney disease (ESKD). Clinical information was analyzed from 348 patients enrolled in the Rare Kidney Stone Consortium Primary Hyperoxaluria registry and included demographic, laboratory and imaging features. Among all patients there were 277 with type 1, 37 with type 2, and 34 with type 3 primary hyperoxaluria. Overall, 58% passed a stone (mean 0.3/year) and one or more urologic procedures were required by 70% of patients (mean 0.15/year). Nephrocalcinosis was found in 34% of patients, including 41% with type 1 primary hyperoxaluria. High urine oxalate was associated with increased risk for both nephrocalcinosis and stone number, while low urine citrate was a risk factor for stone events and stone number. After adjustment for the type of primary hyperoxaluria, diagnosis by family screening and age at first image, the overall adjusted hazard ratio for ESKD among those with a history of nephrocalcinosis was 1.7 [95% CI 1.0-3.0], while the risk was 4.0 [1.9-8.5] for new onset nephrocalcinosis during follow-up. In contrast, the number of stones and stone events were not significantly associated with ESKD risk. Thus, nephrolithiasis and nephrocalcinosis appear to be pathophysiologically distinct entities. The presence of nephrocalcinosis implies increased risk for ESKD.

Microscopic nephrocalcinosis in chronic kidney disease patients.

BACKGROUND: Experimental data indicate that microscopic calcium phosphate deposition in the kidney (nephrocalcinosis) may accelerate progression of chronic kidney disease (CKD). Data on the prevalence, risk factors and implications of nephrocalcinosis in CKD patients are scarce. A mineral metabolism disorder could play an important pathogenetic role, as suggested by recent protocol biopsy findings in incident renal transplant recipients. METHODS: Kidney biopsy cylinders of CKD patients, collected between January 1989 and December 2007, were screened for the presence of nephrocalcinosis. Only patients with ≥1 parathyroid hormone (PTH) level available within 180 days of the biopsy were eligible for inclusion (n = 211). Demographics and mineral metabolism parameters were retrieved from medical files. Data on renal death (up to December 2012) were obtained from the Flemish ESRD registry. Baseline biopsies from 110 deceased kidney transplant donors served as controls. RESULTS: The prevalence of nephrocalcinosis in kidney donors and patients with CKD 1-2, CKD 3-4 and CKD 5-5D was 4.6, 14.3, 20.2 and 54.0%, respectively (P < 0.0001). Among CKD patients, patients with nephrocalcinosis were characterized by lower estimated GFR, lower serum bicarbonate level and higher serum PTH and calcium level. In multivariate regression analysis, high serum PTH, calcium and creatinine level, and low serum bicarbonate level were all significantly and independently associated with nephrocalcinosis. Serum phosphorus level, but not nephrocalcinosis predicted renal death, independent of renal function. CONCLUSIONS: Our data demonstrate that prevalence rates of nephrocalcinosis increase with increasing CKD stage to reach more than 50% in end-stage renal disease patients and suggest that acid-base and mineral metabolism disturbances are implicated in its pathogenesis.