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PubMed1978

Renal magnesium wasting, incomplete tubular acidosis, hypercalciuria and nephrocalcinosis in siblings.

Polyuria, hyposthenuria, hypomagnesemia, hypercalciuria, advanced nephrocalcinosis, low citrate excretion and low glomerular filtration rates were observed in two female siblings who were followed over 10 years. Acid loading revealed incomplete distal tubular acidosis. Hypomagnesemia was due to renal magnesium wasting. It is suggested that the defect in tubular transport of magnesium is an important factor in the pathogenesis of this syndrome.

Acidosis, Renal Tubular↗
PubMed1995

Nephrocalcinosis in a child with autosomal dominant polycystic kidney disease and a prolapsing ectopic ureterocele.

Although autosomal dominant polycystic kidney disease commonly presents in adults, it can occur in children. Usually, renal calcification in patients with autosomal dominant polycystic kidney disease is manifested as calculi or as hemorrhage into a renal cyst. An ectopic ureterocele is a well-known finding in patients with renal duplication. To our knowledge, this is the first case report of a child who had combined findings of autosomal dominant polycystic kidney disease, nephrocalcinosis, and an obstructing ectopic ureterocele.

Child↗
PubMed2001

[Electron beam computed tomography of the heart before kidney transplantation. Severe coronary disease in a 21-year old woman with nephrocalcinosis due to infantile hypercalcemia syndrome].

BACKGROUND: Cardiovascular diseases are very common in patients with end-stage renal disease and are the underlying cause of approximately half the deaths in dialysis patients. In those patients vascular calcifications are typically seen in the tunica media and therefore represent histopathological changes different to those in atherosclerosis. For the evaluation of cardiovascular risk in chronic dialysis patients, a method is needed to reliably identify patients who have to undergo invasive diagnostics. Coronary artery calcium assessed by electron beam computed tomography (EBT) has been suggested to measure the extent of coronary atherosclerosis in patients with normal renal function. It might also be of value in the stratification of cardiovascular risk in patients with renal failure. CASE REPORT: We report the case of a 21-year-old female with end-stage renal disease as a result of idiopathic infantile hypercalcemia with nephrocalcinosis and extensive vascular calcification. Due to a total atrioventricular block, a 2-chamber pacemaker had been implanted in 1998. Because of a very high calcium score in EBT, depressed left ventricular function in echocardiography, and limited physical strength she was sent to coronary angiography. Severe 2-vessel coronary artery disease was found and successfully treated by balloon angioplasty. She was then listed for renal transplantation. Angiographic 6-month follow-up showed an excellent long-term result. CONCLUSION: This case demonstrates that coronary artery disease can also be present in young dialysis patients. Discrimination of atherosclerotic vascular calcification and tunica media sclerosis typical in dialysis patients without hemodynamic effects is difficult. EBT allows for the direct detection of coronary calcium. Its extent correlates with coronary atherosclerosis and the probability of acute coronary syndromes in patients with normal renal function. This evidence has not been proved for dialysis patients, yet. However, EBT may be of value in the stratification of cardiovascular risk for patients awaiting renal transplantation.

Adult↗
PubMed2000

[Sensorineural hearing loss in distal renal tubular acidosis, nephrocalcinosis and microcytic anemia].

Distal renal tubular acidosis is characterized by an impaired H(+)-ion secretion in the distal tubulus. This may cause metabolic acidosis. Among others, patients suffer from retardation and nephrocalcinosis. Here we report about a 3 years old patient with drtA and sensorineural hearing loss. ATP6B1 gene mutation was recently found in patients with drtA sensorineural hearing loss. ATP6B1 expression was demonstrated immunohistochemically in the mouse cochlea and endolymphatic sac. ATP6B1 mRNA was found in the fetal and adult human cochlea. These findings suggest that sensorineural hearing loss in drtA is caused by an disturbed pH homeostasis induced by ATP6B1 mutation.

Acidosis, Renal Tubular↗
PubMed2005

Nephrolithiasis and nephrocalcinosis in rats with small bowel resection.

Intestinal resection (IR) may lead to hyperoxaluria and nephrolithiasis. A rat model of IR was developed, in which kidney stones form. We describe the urine chemistries and histopathologic features. Rats underwent resection of 40-45 cm of distal ileum (n=16) or sham resection (SR) (n=8), and were then fed a 1% Na oxalate, 0.02% Ca diet. After 1 week on the diet, 24 h urine samples were obtained for stone chemistries. At 4-7 months after surgery, kidneys were examined grossly and by light microscopy. The extent and location of crystallization was assessed by polarized light. Histochemistry and infrared spectroscopy were used to determine crystal composition. IR rats had higher urine oxalate excretion (P<0.01) and concentration (P<0.001) than SR rats, and lower urine citrate excretion; only IR rats formed kidney stones (12/15 surviving rats). Tissue calcification was found only in kidneys from IR rats, located in the cortex (83% of kidneys), medulla (73%) and papillary tip (47%). Crystals, composed of CaOx, apatite, and calcium carbonate, filled collecting duct lumens, and were associated with tubular obstruction, and interstitial inflammation. Crystals in the papillary interstitium incited inflammation with tubular destruction and development of progressive papillary erosion. This new rat model of nephrolithiasis and nephrocalcinosis resembles the pattern of urinary abnormalities and tissue calcification that may be seen in humans with small bowel resection. The model allows further studies of the mechanisms of renal crystal formation, and possible therapeutic interventions.

Animals↗
PubMed2000

Nephrocalcinosis and hyperlipidemia in rats fed a cholesterol- and fat-rich diet: association with hyperoxaluria, altered kidney and bone minerals, and renal tissue phospholipid-calcium interaction.

To determine whether an "atherogenic" diet (excess of cholesterol and neutral fat) induces pathological calcification in various organs, including the kidney, and abnormal oxalate metabolism, 24 male Sprague-Dawley rats were fed either normal lab chow (controls, n = 12) or the cholesterol- and fat-rich experimental diet (CH-F, n = 12) for 111 +/- 3 days. CH-F rats developed dyslipidemia [high blood levels of triglycerides, total, low-density lipoprotein (LDL)-, very low-density lipoprotein (VLDL)-, high-density lipoprotein (HDL)-bound cholesterol, total phospholipids], elevated serum total alkaline phosphatase and lactate dehydrogenase (LDH) levels, in the absence of changes in overall renal function, extracellular mineral homeostasis [serum protein-corrected total calcium, magnesium, parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25(OH)2D)], plasma glycolate and oxalate levels. There was a redistribution of bone calcium and enhanced exchange of this within the extraosseous space, which was accompanied by significant bone calcium loss, but normal bone histomorphometry. Liver oxalate levels, if expressed per unit of defatted (DF) dry liver, were three times higher than in the controls. Urinary glycolate, oxalate, calcium and total protein excretion levels were elevated, the latter showing an excess of proteins > 100 kD and a deficit of proteins > 30-50 kD. Urinary calcium oxalate supersaturation was increased, and calcium phosphate supersaturation was unchanged. There were dramatically increased (by number, circumference, and area) renal calcium phosphate calcifications in the cortico-medullary region, but calcium oxalate deposits were not detectable. Electron microscopy (EM) and elemental analysis revealed intratubular calcium phosphate, apparently needle-like hydroxyapatite. Immunohistochemistry of renal tissue calcifications revealed co-localization of phospholipids and calcium phosphate. It is concluded that rats fed the CH-F diet exhibited: (1) a spectrum of metabolic abnormalities, the more prominent being dyslipidemia, hyperoxaluria, hypercalciuria, dysproteinuria, loss of bone calcium, and calcium phosphate nephrocalcinosis (NC); and (2) an interaction between calcium phosphate and phospholipids at the kidney level. The biological significance of these findings for the etiology of idiopathic calcium urolithiasis in humans is uncertain, but the presented animal model may be helpful when designing clinical studies.

Absorptiometry, Photon↗
PubMed1998

Pattern and permanence of phosphate-induced nephrocalcinosis in rabbits.

Objective. The purpose of this study was to observe the pattern and permanence of phosphate-induced nephrocalcinosis (NC) in rabbits. Materials and methods. Thirty immature New Zealand white rabbits were divided into 10 controls and 20 test subjects who were given oral phosphate. Unilateral nephrectomy was performed at 3-6 weeks, and 10 of the test group were withdrawn from the substance. All surviving rabbits were terminated at 6-14 weeks post nephrectomy. Weekly US was performed, as well as US, CT and serum creatinine evaluation at the time of nephrectomy and prior to planned demise. Results. Of the 20 rabbits that received oral phosphate, 16 had NC by 3 weeks and the remainder by 6 weeks. The severity was proportional to intake. NC occurred in the cortex in 69%, the corticomedullary junction (CMJ) in 81% and the medulla in 27% of cases. Only 5 of 10 rabbits that returned to oral water post nephrectomy were suitable for follow-up on pathology. NC improved in 3 of these animals. Conclusion. NC in rabbits occurs maximally at the CMJ but also frequently in the cortex. NC was not permanent or static but improved in 3 of 5 rabbits when phosphate was withdrawn.

Administration, Oral↗
PubMed2003

A girl with rickets and nephrocalcinosis.

A 5-year-old girl presented with short stature. She was found to have rickets due to renal phosphate wasting and nephrocalcinosis. Serum parathyroid hormone was suppressed, 25-OH vitamin D was within the normal range, and 1,25-(OH)(2 )vitamin D was elevated. In addition, she had hypercalciuria, proteinuria, which was partially tubular in origin, and a reduced glomerular filtration rate of 58 ml/min per 1.73 m(2). Treatment with phosphate supplements resulted in healing of the rickets and normalization of the serum 1,25-(OH)(2 )vitamin D level. This patient is an example of hypercalciuric rickets, most likely due to an inherited disorder of phosphate metabolism. Hypercalciuric rickets can be inherited as an autosomal recessive as well as autosomal dominant trait.

Calcium↗
PubMed2003

Urinary NAG in children with urolithiasis, nephrocalcinosis, or risk of urolithiasis.

A crucial role for cell-crystal interactions in the development of urolithiasis (UL) and nephrocalcinosis (NC) was previously observed in experiments with different cell lines mimicking renal epithelial cells. It was found that such cell-crystal interactions lead to tubular damage and/or or dysfunction. To find further proof for these observations, we measured the urinary N-acetyl-beta- d-glucosaminidase (NAG) excretion, a marker of proximal tubular damage, in children with UL or NC and in children with an increased risk of UL. We enrolled 142 children aged 4-16 years (mean 9.67+/-3.40 years), with 50 children having UL, 30 children with a history of UL (ULH), 20 patients with NC, 34 children with secondary hyperoxaluria (HyOx), and 8 children with idiopathic hypercalciuria (HC). Normal urinary NAG/Cr values were determined in a group of 70 healthy children aged 4-16 years (mean 10.06+/-3.97 years). The urinary NAG activity was measured using a colorimetric method and the results were expressed as molar creatinine (Cr) ratios. The highest median NAG/Cr ratios were found in children with UL plus hematuria (0.72 U/mM) and in children with UL (0.67 U/mM) or NC (0.48 U/mM), which were all significantly higher than those in controls (0.28 U/mmol, P<0.001 and P<0.05). The NAG/Cr ratios were increased above the upper normal reference interval of 0.63 U/mM (95th percentile) in 28 of 50 (56%) children with UL and in 9 of 20 (45%) children with NC. Although the ULH group also had significantly higher median NAG/Cr ratios (0.36 U/mM) compared with controls, the NAG/Cr ratio was only elevated in 4 of 30 (13%) patients. NAG values in children with secondary HyOx or HC were not different from controls. No correlation was found between the NAG/Cr ratios and the urinary excretion of oxalate or calcium. In conclusion, UL or NC may result in proximal tubular injury, which is rather the consequence of disease activity and of the mechanical influence of calculi, than of the metabolic background. The mechanism of cell damage in these conditions however, seems to be complex. Neither HyOx nor HC alone were sufficient to induce severe tubular damage expressed as an increase in NAG excretion in our patients.

Acetylglucosaminidase↗
PubMed2003

Preterm neonates with nephrocalcinosis: natural course and renal function.

The aim of the study was to evaluate the natural course of nephrocalcinosis (NC) in preterm neonates and the effect of NC on blood pressure and renal glomerular and tubular function. In a prospective observational study of 201 preterm neonates (gestational age <32 weeks) NC was present at term in 83 patients (41%), who were subsequently examined at 6, 12, and 24 months, and until August 2000 annually (with a maximum of 4 years) if NC persisted. Examination consisted of blood pressure measurement, renal ultrasonography, and glomerular and tubular function tests. The probability that NC, when present at term, would persist for 15 and 30 months was 34% [21-45, 95% confidence interval (CI)] and 15% (5-25, 95% CI) (Kaplan-Meier), respectively. Urinary tract infection did not occur more frequently in patients with NC (2.5%) than patients without NC at term (4.4%). Systolic and diastolic blood pressures above the 95th percentile were found in 39% and 48% of patients at 1 year and 30% and 34% at 2 years ( P<0.001). Mean glomerular filtration rate (GFR) (inulin clearance) at 1 and 2 years was 92 and 102 ml/min per 1.73 m(2), respectively. TP/GFR and excretion of alpha(1)-microglobulin were normal. The desmopressin test was impaired in 4 of 30 patients at 1 year and 2 of 25 at 2 years. It was concluded that while proximal tubular function is unaffected in children with neonatal NC, high blood pressure and impaired glomerular and distal tubular function might occur more frequently than in healthy children. Although no relationship can be proven between NC and hypertension or diminished renal function in this study, these results justify a large follow-up study with matched controlled study groups.

Blood Pressure↗
PubMed2005

Hypocitraturia as a risk factor for nephrocalcinosis after kidney transplantation.

Calcium-oxalate crystal deposition in kidney transplant biopsy specimen led us to investigate the impact of calcineurin inhibitor treatment on urinary excretion of lithogenic and stone inhibitory substances in 53 children after successful kidney transplantation (KTx) receiving cyclosporine A (CsA) or tacrolimus. We compared the values obtained with those of 12 patients with recurrent nephrotic syndrome under CsA and of 6 patients with Rasmussen encephalitis (RE) under tacrolimus therapy. Renal ultrasound examinations were repeatedly performed. Hypocitraturia was found in 69% of patients, with KTx patients having a significantly lower urinary citrate excretion than those receiving calcineurin inhibitors for other reasons. Secondly, we found hyperoxaluria in 35% of patients, again especially in those after KTx. No significant difference in urinary substances was seen comparing CsA with tacrolimus treatment. Urolithiasis was found in one and calcium-oxalate crystal deposition in biopsy specimen of three KTx patients. Calcineurin inhibitor treatment can lead to significant hypocitraturia, especially in patients after KTx receiving the highest dose of medication. Hyperoxaluria is primarily the result of a removal of significant body oxalate stores, deposited during dialysis, but may not be suspected as a specific side effect of calcineurin inhibitor therapy. Both findings can increase the risk for urolithiasis or nephrocalcinosis.

Adolescent↗
PubMed2005

Resolution of medullary nephrocalcinosis in children with metabolic bone disorders.

Ultrasonographic resolution of nephrocalcinosis (NC) has been reported in children with furosemide-induced NC, but not in other entities. We report the cases of four children with metabolic bone disease, two with hypophosphatasia and two with X-linked hypophosphatemic rickets, in whom we observed resolution of renal calcifications. At the time of ultrasonographic resolution of NC, 3 of the patients were on anticalciuric diuretics, and all 4 had normal urinalysis, serum creatinine and electrolyte profiles, as well as estimated creatinine clearance. In 3 of the children, evidence of mild tubular dysfunction was found. It thus seems that in some children with bone and mineral disorders who develop NC, ultrasonographic resolution of the renal calcifications can be seen; however, mild tubular dysfunction may remain and require follow-up. Further studies are suggested to explore the possible role of anticalciuric diuretics in promoting the resolution of NC.

Adolescent↗
PubMed2005

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis associated with CLDN16 mutations.

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC), an autosomal recessive renal tubular disorder, is characterized by the impaired tubular reabsorption of magnesium and calcium in the thick ascending limb of the loop of Henle and an eventual progression to end-stage renal disease. Recent studies have reported that this disease is caused by mutations in the CLDN16 gene, which encodes the tight junction protein, paracellin-1. Paracellin-1 belongs to the claudin family and regulates the paracellular transport of magnesium and calcium. Here, we report on two Korean siblings with typical clinical features of FHHNC in association with compound heterozygous mutations, G233C and 800delG, in CLDN16. Their parents were asymptomatic heterozygous carriers of the single mutations. This is the first report of FHHNC in Korea, and the mutations reported are novel.

Base Sequence↗
PubMed2006

Does citrate prevent nephrocalcinosis in preterm neonates?

Nephrocalcinosis (NC) occurs frequently in preterm neonates. A high U-calcium/citrate is one of the contributing factors to the development of NC. In stone-forming children and adults citrate supplementation is a successful preventive therapy. In this randomized controlled trial the effect of citrate therapy was studied on the development of NC in preterm neonates with a gestational age <32 weeks. Thirty-eight preterm neonates (mean gestational age 29.8 weeks (SD 1.6), mean birth weight 1,300 g (SD 351) were treated with sodium citrate (0.52 mmol/kg/day in four doses) from day 8 of life until at term and 36 preterm neonates (mean gestational age 29.6 weeks (SD 1.6), mean birth weight 1,282 g (SD 256) were not treated. U-calcium, U-creatinine, U-citrate and U-pH were measured at day 7, 14, 21, 28 of life and at term. Renal ultrasonography (US) was performed at term. U-citrate/creatinine and U-pH were significantly higher and U-calcium/citrate was significantly lower in the citrate group at day 14, 21 and 28 compared with the control group (P<0.05). Complications of citrate administration were not encountered, however the incidence of NC was not significantly different in the treated (34%) compared with the control group (44%), P=0.37. Preterm neonates treated with citrate in the first months of life have higher U-citrate/creatinine and lower U-calcium/citrate compared with controls. Sodium citrate therapy in a dosage of 0.52 mmol/kg/day is safe but does not prevent NC. Whether a higher dose or potassium citrate decreases the incidence of NC should be evaluated in further studies.

Citric Acid↗
PubMed2000

Effect of thiazide on established furosemide-induced nephrocalcinosis in the young rat.

A previous study on furosemide-induced nephrocalcinosis (NC) showed only partial resolution of the calcifications after discontinuation of the diuretic. We investigated whether treatment with chlorothiazide (CTZ) will expedite the resolution of established furosemide-induced NC. Seventy-eight weanling male Sprague-Dawley rats were divided into eight groups. Three groups were studied for 1 week: A, control; B, furosemide 40 mg/kg per 24 h; C, CTZ 100 mg/kg per 24 h. Five groups were studied for 5 weeks: D, control; E, F, G, furosemide 40 mg/kg per 24 h for 1 week followed by 4 weeks of observation (E), CTZ 50 mg/kg per 24 h (F), and CTZ 100 mg/kg per 24 h (G) and; and CTZ 100 mg/kg per 24 h (H) for 5 weeks. At the end of each study period urine and blood were collected, one kidney was studied histologically and the contralateral ashed for quantitative calcium (Ca) analysis. Animals in group B developed NC with a kidney Ca content of 1,844 +/- 203 micrograms/g dry tissue compared with group A 248 +/- 86 (P < 0.05) and group C 256 +/- 56 (P < 0.05). There were no differences among the three groups with regard to creatinine clearance, urine phosphate (P) or Ca excretion, although the latter tended to be lower in group C. Animals in group E showed a reduction in the magnitude of NC, with kidney Ca of 550 +/- 398 micrograms/g dry tissue, which was lower than in group B (P < 0.05) but still higher than in groups D (140 +/- 27) (P < 0.05) or H (162 +/- 63) (P < 0.05). Kidney Ca content in groups F (497 +/- 142) and G (489 +/- 271 micrograms/g dry tissue) was similar to that in group E. There were no differences among the five groups with regard to creatinine clearance or urine P excretion. Urine Ca excretion was significantly lower in groups F and G than groups D and E. We conclude that once established, NC caused by furosemide is not affected by CTZ therapy in spite of the anticalciuric property of the latter.

Animals↗
PubMed2000

Nephrocalcinosis in children: a retrospective survey. Members of the Arbeitsgemeinschaft für pädiatrische Nephrologie.

We carried out a retrospective survey on 152 children and adolescents with nephrocalcinosis (NC) in 22 German centers of pediatric nephrology. Etiology, clinical manifestations, growth and development, sonographic appearance of NC and renal function were analyzed. The median age at the time of diagnosis was 3.3 (range 0.1-21) years and the median duration of follow-up was 4.1 years. In 34% of children NC was associated with idiopathic hypercalciuria (IHC) and in 32% with various hereditary tubular disorders. In 9% NC was observed subsequent to prophylactic bolus administration of vitamin D in infancy. A positive family history was found in 36%. Clinical manifestations were mainly failure to thrive during the 1st year of life (46%), psychomotor/mental retardation (28%) and urinary tract infection (34%). In 14% nephrolithiasis was associated. During the follow-up the proportion of patients with the most severe degree of NC (stages 2b or 3) increased from 40% to 55% and that of hypercalciuria decreased from 79% to 52%. Body height was <2 standard deviation scores (SDS) of normal in 41% at the time of diagnosis and in 32% at the last observation; the increase in relative height was significant only for IHC. Glomerular filtration rate (GFR) and urinary concentration capacity changed only slightly with time. At the last investigation GFR was <50 ml/min/1.73 m2 in 6% and concentration capacity <800 mosmol/kg in 48% of patients. The degree of NC was negatively correlated with GFR and concentration capacity.

Adolescent↗