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Osteomalacia due to 1alpha,25-dihydroxycholecalciferol deficiency. Association with a giant cell tumor of bone.

Oncogenic osteomalacia is a syndrome in which unexplained osteomalacia remits after resection of a coexisting mesenchymal tumor. We have investigated the mechanism by which a giant cell tumor of bone caused biopsy-proved osteomalacia in a 42-yr-old woman. The biochemical abnormalities were: hypophosphatemia; decreased renal tubular maximum for the reabsorption of phosphate per liter of glomerular filtrate; negative calcium and phosphorus balance; hyperaminoaciduria; and subnormal calcemic response to exogenously administered parathyroid hormone. Malabsorption, hypophosphatasia, fluorosis, and acidosis were excluded as causes of the osteomalacia. Serum 25-hydroxycholecalciferol was normal (27+/-1 ng/ml). However, the serum concentration of 1alpha,25-dihydroxycholecalciferol was low (1.6+/-0.1 ng/100 ml). Oral administration of physiological amounts of 1alpha,25-dihydroxycholecalciferol resulted in resolution of the biochemical abnormalities of the syndrome and healing of the bone pathology. We suggest that tumor-induced inhibition of 1alpha,25-dihydroxycholecalciferol synthesis caused the osteomalacia. The causal role of the tumor was proved by demonstrating that resection was accompanied by roentgenographic evidence of bone healing and maintenance of normal serum phosphorus; renal tubular maximum for the reabsorption of phosphate; calcium and phosphorus balance; aminoaciduria; and calcemic response to exogenous parathyroid hormone.

Adult↗

Effect of cisplatin on renal function in rabbits: mechanism of reduced glucose reabsorption.

This study was performed to determine the effect of cisplatin (cis-diamminedichloroplatinum II) on renal function in rabbits. Injection of a single i.p. dose of 4 mg/kg cisplatin caused an increase in fractional excretion of Na+ and K+ and a decrease in urine osmolality (Uosm), free-water reabsorption, (TcH2O), and urine to plasma creatinine ratio (U/Pcr). Urine flow was decreased following cisplatin treatment, which was accompanied by marked reduction in GFR. Cisplatin induced glucosuria, phosphaturia, and aminoaciduria. These results suggest that cisplatin results in impaired proximal tubular reabsorptive function and the renal concentrating defect. Cisplatin treatment impaired the accumulation of PAH and TEA and ouabain-sensitive oxygen consumption in renal cortical slices. Na(+)-K(+)-ATPase activity in renal cortical microsomes and basolateral membrane vesicles was significantly depressed in cisplatin-treated animals. Cisplatin treatment did not affect the Na(+)-dependent uptake of glucose and L-glutamate by brush-border membrane vesicles (BBMV), but caused a significant decrease in Na(+)-dependent succinate and H(+)-dependent TEA uptake. Morphological observations showed that cisplatin caused a focal loss of the microvillus brush border. These results suggest that (1) cisplatin induces oliguric acute renal failure in rabbits and (2) glucosuria induced by cisplatin was not due to a direct impairment of glucose transporter in brush-border membranes but due to an inhibition of Na(+)-pump activity and a decrease in area for active glucose reabsorption in the proximal tubule.

Amino Acids↗

[Renal excretion of amino acids in patients on a regular dialysis program].

In 10 patients with chronic renal failure and a polyfructosan S clearance (CPFS): 1.91-12.70 ml/min (mean 5.68 ml/min) with a preserved residual diuresis (more than 1000 ml/24 hours) renal excretion of 22 amino acids by residual nephrons was investigated before and 12 hours after haemodialysis. It was revealed that 12 hours after haemodialysis a significant drop of the filtered amount of all investigated amino acids occurred. Renal clearance of Ser, Pro, Glu, Gly, Ala, Tyr, Met, Leu and Cit after haemodialysis declined significantly (p < 0.05-0.001). Haemodialysis was not associated with significant changes of fractionated excretions (FE) of amino acids with the exception of Gly (p < 0.01) and Trp (p < 0.05) where an increase of FE was recorded. Hitherto assembled results are consistent with the idea that a reduction of the tubular resorption of amino acids in the residual nephrons in subjects with chronic renal failure cannot be explained by a change of their filtered amount (as "overflow" aminoaciduria) nor as the consequence of retention of some dialyzable substances which could inhibit tubular transport of amino acids. The reduced tubular transport of some of the investigated amino acids (Cys, Lys, Cit, Met, Asn+Gln, Orn, Ile) was significantly related with the drop of tubular sodium transport.

Adult↗

Renal tubular function in children and adolescents with Gitelman's syndrome, the hypocalciuric variant of Bartter's syndrome.

Renal tubular function was studied in 14 patients with Gitelman's syndrome and 14 control subjects. Apart from the biochemical hallmarks of Gitelman's syndrome, namely alkalaemia, hyperbicarbonataemia, hypokalaemia, hypomagnesaemia (with increased magnesium over creatinine ratio), increased urinary chloride over creatinine ratio, and low urinary calcium over creatinine, the patients were found to have hyperproteinaemia, hypochloraemia, high total plasma calcium concentration, reduced plasma ionized calcium concentration, and high urinary sodium excretion. A statistically significant negative linear relationship between plasma magnesium concentration and magnesium excretion corrected for glomerular filtration was observed in patients. The fractional calcium clearance and the urinary excretion of calcium corrected for glomerular filtration was significantly decreased in patients. In patients the urinary osmolality after overnight water deprivation ranged from 526 to 1067 mmol/kg. Glucosuria and aminoaciduria were similar in patients and controls. The results of the study demonstrate the renal origin of hypomagnesaemia and hypocalciuria in Gitelman's syndrome. The failure to demonstrate hyperaminoaciduria, hyperglucosuria, hyperphosphaturia, hyperuricosuria, and severely impaired urinary concentrating ability provide evidence for a defect residing in the distal convoluted tubule.

Adolescent↗

Renal tubular function in cyclosporine-treated patients.

Renal tubular function was studied in 32 consecutive patients treated with cyclosporine for autoimmune uveitis. Cyclosporine dosage was modified to maintain the serum creatinine level at less than 2 mg/dl. No evidence of aminoaciduria, glucosuria, hypokalemia, hypophosphatemia, or hypouricemia indicative of the Fanconi syndrome was detected during three to six months of observation. The renal tubular reabsorption of phosphate, determined by renal threshold phosphate concentration (TmPO4/GFR), remained unchanged. An early decrease in the serum magnesium level was accompanied by a decrease in daily urinary magnesium excretion. Concurrent with the development of a mild reduction of the glomerular filtration rate, the fractional excretion of magnesium was slightly higher and that of calcium was lower than pretreatment values. There were modest elevations of serum uric acid and potassium values. Furthermore, lysozymuria was not observed. Thus, the alterations in tubular functions observed in our cyclosporine-treated patients are comparable to those associated with mild chronic renal insufficiency of various causes and are not specific manifestations of cyclosporine tubular toxicity.

Adolescent↗

Ascorbic acid and amino acid values in the aqueous humor of a patient with Lowe's syndrome.

BACKGROUND: Aminoaciduria is found in Lowe's syndrome. No studies of concentrations of ascorbic acid and amino acids in the aqueous humor of the syndrome have been performed. We examined these concentrations in a patient with Lowe's syndrome. METHODS: Ascorbic acid and amino acid levels in the aqueous humor and plasma of a male infant were measured by means of high-performance liquid chromatography. The patient, who had congenital cataract, miotic pupils, opaque corneas, glaucoma, aminoaciduria, normal levels of ascorbic acid and amino acid in the plasma, and renal tubular acidosis, underwent trabeculotomy, lensectomy, and anterior vitrectomy in both eyes. RESULTS: Intraocular pressure in both eyes decreased to within the normal range, but both corneas remained opaque. The amino acid levels in the aqueous humor were similar to those in the plasma, but intracameral ascorbic acid levels were decreased. After topical instillation of ascorbic acid, the corneas became transparent. The proband's mother had good visual acuity but paracentral lens opacities in both eyes. His maternal grandmother had scattered cortical opacities in both lenses. CONCLUSION: In this infant with Lowe's syndrome, we found intracameral levels of amino acids similar to those in the plasma. Levels of ascorbic acid in the aqueous humor were decreased.

Adolescent↗

Characterization of the proteinuria induced by prolonged oral administration of cadmium in female rats.

Female Sprague-Dawley rats were given 200 ppm cadmium (Cd) in the drinking water for 11 months. Total proteinuria and the concentrations of Cd in blood, urine, liver and kidney cortex were determined monthly. The proteinuria was characterized by Sephadex G-75 chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. From the 8th month of treatment, the Cd concentration in the kidney cortex levels off at a value of about 250 microgram/g wet wt and this phenomenon coincides with the occurrence of proteinuria. The proteinuria was characterized by an increased urinary excretion of high molecular weight (HMW) proteins, particularly gamma-globulins. Aminoaciduria also increased which suggests the existence of a slight tubular dysfunction. The renal dysfunction induced by chronic oral administration of Cd seems different from that observed in a previous study in which Cd was administered by the i.p. route (1 mg Cd/kg, 5 times a week for 2 months). For the same level of Cd in the kidney cortex the proteinuria induced by i.p. injection of Cd was usually of mixed type and in some cases of the tubular type. The development of this proteinuria was coincident with the levelling off of Cd concentration in the kidney cortex and in the liver. The saturation of liver by Cd is very likely at the origin of he extensive tubular lesion and of the mixed type proteinuria observed in the i.p. experiment. These results demonstrate the importance of mode of Cd administration on the nature of the Cd-induced proteinuria in animal. They support also our proposal that both low and HMW proteins should be determined in urine for the early detection of renal damage occurring in man chronically exposed to cadmium.

Administration, Oral↗

Genomic organization of a human cystine transporter gene (SLC3A1) and identification of novel mutations causing cystinuria.

Cystinuria is a common inherited aminoaciduria that leads to recurrent cystine nephrolithiasis. Mutations in a gene encoding a renal amino acid transporter (SLC3A1) have been identified in patients with cystinuria establishing one molecular cause for the disease. To facilitate systematic screening of this gene for mutations, we have delineated the complete genomic organization of the SLC3A1 coding region using polymerase chain reaction strategies. The complete coding region of the gene is contained within a single yeast artificial chromosome clone and consists of 10 exons and 9 introns. Oligonucleotide primers capable of amplifying selected exons have been made and used in mutational analysis of DNA from 24 cystinuria probands. We illustrate the usefulness of this approach by identifying two novel SLC3A1 mutations. One novel mutation causes replacement of a highly conserved arginine residue (arginine-452) with tryptophan in the cytoplasmic loop between the putative third and fourth membrane spanning segments. A second previously unreported mutation results in replacement of a highly conserved tyrosine (tyrosine-461) residue with histidine in the same region of the protein. In addition, we detected three previously reported SLC3A1 mutations, R270X, 1500 +1/G to T, and M467T, the latter being present in approximately 20% of cystinuria chromosomes examined. Our findings provide a foundation for the development of more accessible diagnostic screening assays for detecting SLC3A1 mutations using patient genomic DNA, and also contribute to the emerging spectrum of cystinuria genotypes.

Amino Acid Sequence↗

Renal effects of environmental and occupational lead exposure.

Environmental and industrial lead exposures continue to pose major public health problems in children and in adults. Acute exposure to high concentrations of lead can result in proximal tubular damage with characteristic histologic features and manifested by glycosuria and aminoaciduria. Chronic occupational exposure to lead, or consumption of illicit alcohol adulterated with lead, has also been linked to a high incidence of renal dysfunction, which is characterized by glomerular and tubulointerstitial changes resulting in chronic renal failure, hypertension, hyperuricemia, and gout. A high incidence of nephropathy was reported during the early part of this century from Queensland, Australia, in persons with a history of childhood lead poisoning. No such sequela has been found in studies of three cohorts of lead-poisoned children from the United States. Studies in individuals with low-level lead exposure have shown a correlation between blood lead levels and serum creatinine or creatinine clearance. Chronic low-level exposure to lead is also associated with increased urinary excretion of low molecular weight proteins and lysosomal enzymes. The relationship between renal dysfunction detected by these sensitive tests and the future development of chronic renal disease remains uncertain. Epidemiologic studies have shown an association between blood lead levels and blood pressure, and hypertension is a cardinal feature of lead nephropathy. Evidence for increased body lead burden is a prerequisite for the diagnosis of lead nephropathy. Blood lead levels are a poor indicator of body lead burden and reflect recent exposure. The EDTA lead mobilization test has been used extensively in the past to assess body lead burden. It is now replaced by the less invasive in vivo X-ray fluorescence for determination of bone lead content.

Adult↗

Distal renal tubular acidosis in multiple myeloma.

A patient with early multiple myeloma was initially seen with a severe hyperchloremic metabolic acidosis with a normal anion gap and a urine pH of 6.3. The patient did not have glucosuria, aminoaciduria, of phosphaturia. A bicarbonate loading test showed that the fractional excretion of bicarbonate was less than 5% and confirmed the hypothesis that the patient had a distal renal tubular acidification defect. The pathophysiologic mechanism that caused this defect is unknown, but it is associated with the presence of a serum M component (IgG-lambda) and a urine M component (lambda light chains). Multiple myeloma should be considered in the differential diagnosis of conditions of patients who have a renal tubular acidification defect.

Acidosis, Renal Tubular↗

Adult onset Fanconi syndrome: extensive tubulo-interstitial lesions and glomerulopathy in the early stage of Chinese herbs nephropathy.

A 33-year-old woman was transferred to our hospital with a 5-month history of taking Chinese herbal medicine containing aristolochic acid. She presented with metabolic acidosis, severe anemia, hypophosphatemia and uric aciduria, and generalized aminoaciduria and glycosuria, features which were consistent with the clinical manifestations of Fanconi syndrome. Renal biopsy was performed when her plasma creatinine was 0.7 mg/dl and creatinine clearance was 46 ml/min per 1.73 m(2). The renal specimen showed extensive interstitial edema with focal fibrosis, tubular atrophy, and focal glomerulopathy, which suggested the presence of glomerular endothelial damage or glomerular ischemia. Although steroid therapy ameliorated the plasma electrolyte levels, renal failure progressed, and hemodialysis therapy was initiated approximately 18 months after the time of renal biopsy. This patient demonstrated the early renal lesions of Chinese herbs nephropathy in association with various clinical manifestations. The characteristic glomerulopathy found in the present patient is considered to be an additional renal lesion, leading to the renal failure.

Adult↗

Fanconi syndrome associated with a non-ossifying fibroma of bone.

A 20-year-old man presenting with osteomalacia was found to have the Fanconi syndrome, as evidenced by hypophosphatemia with hyperphosphaturia, glycosuria in the presence of normoglycemia, and generalized aminoaciduria. After removal of a non-ossifying fibroma of the left tibia, the renal tubular abnormalities promptly resolved with subsequent healing of the osteomalacia. A humoral factor released from the tumor may have caused the disorder in proximal renal tubular cell transport.

Adult↗

[Acute tubulointerstitial nephritis in children].

UNLABELLED: Acute tubulointerstitial nephritis (ATIN) is a rare renal disorder in children. Patients usually present non-specific symptoms and signs so that the diagnosis of ATIN is often delayed. The disease may be infection- or drug-induced or it may occur without a known cause. Early recognition and appropriated therapy usually lead to an excellent prognosis. The aim of the study was to describe clinical and laboratory findings and the course of ATIN in 21 patients, that are typical enough to enable early recognition of the disease as it is potentially reversible. METHODS: Between 1986 and 1997 we observed 21 patients, aged 7-16 years (mean, 12.8), with acute tubulointerstitial nephritis, including eight with tubulointerstitial nephritis and uveitis (TINU syndrome). Laboratory studies included urinalysis, complete blood count, erytrocyte sedimentation rate (ESR), plasma creatinine, glomerular filtration rate (GFR), electrolytes, proteins, IgG, C3, C4 antinuclear-antibodies (ANA), antistreptolysin-O and antibodies to hantaviruses. Renal ultrasound was done in all patients. Renal biopsy was performed in 5 children. RESULTS: All children had previously been healthy. The symptoms of ATIN developed within a few days (Table 1). The most common initial symptoms were fatigue, fever, gastrointestinal disturbances, anorexia and weight loss. Less common complaints included headache, arthralgias and maculopapular rash. On addmition no patient had hypertension, oedema or evidence of acute infection. ESR, plasma urea and creatinine concentrations were increased in all, plasma proteins and IgG levels in the majority of patients. ANA were negative in 15 pts in whom this analysis was performed; C3 and C4 levels were normal. In two children recent strepococcal and in the other 6 hantavirus infection was serologicaly proved. All patients had non-oliguric acute renal failure (ARF): GFR was 21.7 +/- 8 9 in 14 pts and 67 +/- 9.7 in 7 pts. Low urine specific gravity (1003-1014), mild proteinuria (0.3-0.4 g/24 h), leukocyturia and/or haematuria were found in all patients; glycosuria, aminoaciduria and decreased tubular reaposrption of phosphate (TRP) were found in 12/21, 9/21 and 9/14 patients, respectively. Urine cultures were negative in all children. Renal US demonstrated enlarged hyperechoic kidneys in 11 pts, in remaining 10 pts no abnormalities were found. Renal biopsy, performed in 5 children, confirmed the diagnosis of ATIN. Eight patients subsequently developed anterior uveitis as part of TINU syndrome. Treatment included supportive therapy in all and six patients received prednisolone for 4-8 weeks (40-60 mg/m2/24 h for 10-14 days with subsequent reduction of dose over several weeks). Anterior uveitis was successfully treated with topical steroids. Renal function completely recovered in all patients: GFR (109 +/- 22.6 ml/min) within a mean interval of 47 +/- 33 days, concentration ability within 2-12 (mean 4.5) months. DISCUSSION: Common clinical features of ATIN are non-oliguric acute renal failure of various degrees, signs of tubular dysfunction, proteinuria, haematuria, leukocyturia and absence of hypertension. All our patients had normal blood pressure, non-oliguric renal failure, proteinuria, hypostenuria and abnormal urinary sediment; about half of them had glycosuria and/or other signs of proximal tubular dysfunction. The most important causes of ATIN in children reported in literature are systemic infections and drugs. However, the cause of ATIN in our patients was assessed as being related to infection only in 8 patients and to diclofenac in one. No infection, drug, toxin or other cause could be identified in 4, as well as in 8 pts with TINU syndrome. The prognosis of ATIN in children is considered to be favourable, but some patients may develop chronic renal failure. Renal function completely recovered in all our patients; that is consistent with outcome data from the most reports. CONCLUSION: Acute tubulointerstitial nephritis is an important cause of ARF in children, its aetiology may be different and it carries an excellent prognosis. ATIN should be suspected in a child who presents typical, although non-specific symptoms and signs, associated with lukocyturia and/or microhaematuria, signs of tubular dysfunction and unexplained renal failure. The diagnosis can be verified at renal biopsy. Early recognition of the disease is important to remove possible aetiologic agents and to treat them before chronic lesions are present to avoid long-term renal damage.

Acute Disease↗

Paraquat-induced Fanconi syndrome.

The ingestion of paraquat, a non-selective herbicide, can be fatal in humans. Paraquat is toxic to multiple organs, including the kidney, heart, gastrointestinal tract and central nervous system. Although paraquat has been established as one cause of acute tubular necrosis, Fanconi syndrome presenting as severe hypophosphataemia after paraquat intoxication has not been reported. Here, we report the case of a 44-year-old Korean woman who presented with generalized proximal tubular dysfunction including aminoaciduria, phosphaturia and glycosuria after paraquat intoxication. We found that severe hypophosphataemia induces deep drowsiness. Renal biopsy findings indicated the presence of acute tubular necrosis that may be reversible.

Adult↗

An adult case of Fanconi syndrome due to a mixture of Chinese crude drugs.

We examined a 35-year-old male case of acquired Fanconi syndrome induced by a mixture of Chinese crude drugs. Renal glycosuria, hypokalemia, hypophosphatemia, metabolic acidosis, a low threshold of tubular bicarbonate excretion, and generalized aminoaciduria were observed after the patient had taken the drugs for 6 months. When he stopped taking them, all laboratory data improved. He took the drugs again on his own judgment, leading to a second bout of Fanconi syndrome. This is the first case in which Chinese crude drugs have been known to cause acquired Fanconi syndrome.

Adult↗

Autosomal recessive renal proximal tubulopathy and hypercalciuria: a new syndrome.

BACKGROUND: The best described primary inherited proximal tubulopathies include X-linked hypercalciuric nephrolithiasis (XLHN), caused by a mutation in the chloride channel gene CLCN5, and classic Fanconi's syndrome, the genetic basis of which is unknown. The aim of this study is to examine the clinical, biochemical, and genetic characteristics of a highly consanguineous Druze family with autosomal recessive proximal tubulopathy and hypercalciuria (ARPTH), a syndrome not reported previously. METHODS: Three children (2 girls, 1 boy) of the family referred for evaluation of renal glycosuria and hypercalciuria and 10 of their close relatives were evaluated clinically and biochemically. All study participants underwent genetic analysis to exclude involvement of the CLCN5 gene. RESULTS: Evaluation of the 3 affected children showed glycosuria, generalized aminoaciduria, hypouricemia, uricosuria, low molecular weight (LMW) proteinuria, and hypercalciuria in all 3 children and phosphaturia in 2 children. They had no metabolic acidosis or renal insufficiency. One affected girl had nephrocalcinosis. Two children had a history of growth retardation and radiological findings of metabolic bone disease. Parathyroid hormone and 1,25-dihydroxyvitamin D [1,25(OH)2Vit D] blood levels in affected children were normal. Unaffected family members examined had no renal tubular defects or LMW proteinuria. Genetic linkage analysis excluded cosegregation of the ARPTH phenotype with the CLCN5 locus. CONCLUSION: ARPTH is a new syndrome characterized by nonacidotic proximal tubulopathy, hypercalciuria, metabolic bone disease, and growth retardation. It can be distinguished from XLHN by its autosomal recessive mode of inheritance and normal serum levels of calciotropic hormones, as well as the absence of LMW proteinuria in obligate carriers. The gene mutated in ARPTH remains to be identified.

Bone Diseases, Metabolic↗

A renal lesion in asphyxiating thoracic dysplasia.

A boy with asphyxiating thoracic dysplasia was studied from age seven months until his death with congestive heart failure at age thirteen months. Aminoaciduria, phosphaturia, increased urate excretion, hyposthenuria, proteinuria, and metabolic acidosis were demonstrated at one year of age. Cardiopulmonary dysfunction and skeletal abnormalities were also studied during life. Cessation of linear growth, overgrowth of membranous bone with retardation of enchondral bone formation, and cartilaginous overgrowth of the chest were prominent findings. At autopsy, an unexpected hepatic fibrosis was discovered, along with renal and skeletal disorganization.

Bone and Bones↗

Spontaneous Fanconi syndrome in the dog.

Three dogs with spontaneous renal tubular defects similar to idiopathic Fanconi syndrome are characterized. Renal clearance studies revealed a fractional reabsorption of glucose ranging from 31% to 82%. Abnormal glucose thulium values were present in all dogs. A generalized aminoaciduria occurred in two dogs while one had aminoaciduria characteristic of canine cystinuria. Fractional reabsorption of phosphate ranged from 47% to 79%. In vitro uptake of alpha-methyl-D-glucoside was significantly depressed (p less than 0.001). In vitro uptake of amino isobutyric acid was similar to controls. Renal biopsy revealed nonspecific interstitial change in two dogs and normal histology in the other. These animals represent a useful new model for the study of renal tubular transport defects.

Amino Acids↗