Aminoaciduria Caused by Fanconi Syndrome in a Heifer.

A case study of renal tubular dysfunction consistent with idiopathic Fanconi syndrome is reported in an 18-month-old Holstein heifer. The clinical, biochemical, and histopathological features are described. The heifer had clinical signs of growth retardation, wasting, and persistent diarrhea. Biochemical blood analysis identified hypokalemia, hyponatremia, and hypochloremia. Urinalysis identified glycosuria, proteinuria, and acidic pH. Histological examination of the kidney disclosed mild tubular necrosis with proteinaceous casts in the lumina of renal tubules. We performed LC-HRMS on urine to confirm Fanconi syndrome. Using this technique, we identified severe generalized aminoaciduria suggestive of idiopathic renal Fanconi syndrome in this heifer.

Cuantificación de cistina en orina espontánea para la detección de cistinuria / Quantitation of urinary cystine for the detection of cystinuria / Determinagáo quantitativa de cistina urinaria para a detecgáo de cistinuria

La cistinuria es un error innato del metabolismo ocasionado por un defecto en el transporte renal de arginina, ornitina, lisina y cistina. La acumulación de este último aminoácido de baja solubilidad ocasiona episodios de urolitiasis característicos de la enfermedad. En el presente estudio se estandarizó un método espectrofotométrico confiable y de fácil ejecución para la determinación cuantitativa de cistina en orina espontánea. Se realizó el análisis en 184 muestras, correspondientes a 104 controles y 80 pacientes con urolitiasis. Con el objeto de validar el método y posteriormente establecer un rango de excreción normal en la población colombiana se evaluaron los siguientes parámetros: exactitud, precisión, linealidad y límite de detección. La técnica mostró coeficientes de variación intra e inter ensayos inferiores al 10% y una excelente linealidad, con un coeficiente r² entre concentraciones conocidas de cistina y absorbancia generada por el método de 0,998. Usando esta técnica se encontró un valor normal de excreción de 1,35 a 110,11 mg cistina/g creatinina. En cinco pacientes, de los 80 con nefrolitiasis, se hallaron valores elevados de cistina, compatibles con cistinuria. El método utilizado puede implementarse en cualquier laboratorio clínico para confirmar el diagnóstico de cistinuria e iniciar un tratamiento oportuno.

Cystinuria is an inborn error of metabolism, caused by a defect in renal tubular transport of the following aminoacids: arginine, ornithine, lysine and cystine. Accumulation of the latter poorly soluble aminoacid leads to the development of kidney stones, characteristic of the disease. In this study, an easy and dependable spectrophotometric method for the quantitative determination of urinary cystine was standardized. The analysis was performed on 184 samples from 104 controls and 80 patients with kidney stones. In order to validate the method and later establish a range of normal urinary cystine excretion in the Colombian population, the following parameters were evaluated: Accuracy, precision, linearity and lower limit of detection. The technique showed intra and intei assay coefficients of variation below 10%, and excellent linearity, with an R square (r²) coefficient between known cystine concentrations and absorbance generated by the method at 0.998. Using this technique, a normal urinary cystine excretion range of 1.35-110.11 mg cystine/g creatinine was found. Among the 80 patients with kidney stones, elevated urinary cystine levels were found in 5 of them, compatible with the presence of cystinuria. This method can be implemented in any clinical laboratory to confirm the diagnosis of cystinuria and provide opportune treatment.

A cistinúria é um erro inato do metabolismo, causado por um defeito no transporte tubular renal de ar-ginina, ornitina, lisina e cistina. A acumulagáo deste último aminoácido, pouco solúvel, provoca episodios de urolitíase, característicos da doenga. No presente estudo, foi padronizado um método espectrofotomé-trico confiável e de fácil execugáo para a determinagáo quantitativa de cistina em urina espontánea. A análise foi realizada em 184 amostras de 104 controles e 80 pacientes com urolitíase. A fim de validar o método e, posteriormente, estabelecer um intervalo de excregao normal na populagao colombiana, foram avaliados os seguintes parámetros: exatidáo, precisáo, linearidade e limite inferior de detecgáo. O método mostrou coeficientes de variagáo intra e inter ensaios inferiores a 10%, e excelente linearidade, com um coeficiente R quadrado (r²) entre concentragoes conhecidas de cistina e absorváncia gerada pelo método de 0,998. Com esta técnica, foi encontrado um valor normal de excregáo de 1,35-110,11 mg cistina/g de creatinina. Entre os 80 pacientes com urolitíase, foram encontrados níveis elevados de cistina em cinco deles, compatíveis com a presenga de cistinúria. Este método pode ser implementado em qualquer laboratorio clínico para confirmar o diagnóstico de cistinúria e proporcionar um tratamento oportuno.

Effect of hydrochlorothiazide on urinary calcium excretion in dent disease: an uncontrolled trial.

BACKGROUND: Thiazide doses equivalent to 1 to 2 mg/kg/d of hydrochlorothiazide (HCTZ) have been proposed to correct hypercalciuria and prevent kidney failure in patients with Dent disease. However, they can cause adverse metabolic effects in the long term. In treating hypertension in children, lower thiazide doses have been shown to be as effective and well tolerated. STUDY DESIGN: Uncontrolled trial, with forced-titration sequential open-label study design. SETTING & PARTICIPANTS: 7 boys with genetically confirmed Dent disease and mild phenotype (neither overt sodium wasting nor kidney failure). INTERVENTION: After a 1-month run-in period, patients sequentially received amiloride (5 mg/d) alone (1 month) and then for 3 periods of 2 months in association with increasing doses of HCTZ (<0.2, 0.2 to 0.4, and 0.4 to 0.8 mg/kg/d). OUTCOMES: Urinary calcium excretion and extracellular volume indicators. MEASUREMENTS: At the end of each period, 2 daily 24-hour urinary collections were performed on the days preceding admission. Blood and spot urine samples also were collected. RESULTS: A greater HCTZ dose increased renin, aldosterone, and plasma protein concentrations. Amiloride alone had no effect on calcium excretion. The greatest HCTZ doses decreased spot urinary calcium excretion by 42% compared with baseline (median, 0.3; minimum, maximum, 0.2, 0.8 versus median, 0.8; minimum, maximum, 0.4, 1.1, respectively; P = 0.03). However, patients developed adverse reactions, including muscle cramps (n = 2), biological (n = 7) or symptomatic hypovolemia (n = 1), hypokalemia (n = 4), and hyponatremia (n = 1), which all corrected after treatment withdrawal. LIMITATION: Small sample size and absence of a control group. CONCLUSION: HCTZ doses greater than 0.4 mg/kg/d decreased calcium excretion, but were associated with significant adverse events. Thiazide diuretic therapy should be considered with caution in children with Dent disease.

L-2-Hydroxyglutaric aciduria: clinical, biochemical and magnetic resonance imaging in six Portuguese pediatric patients.

We present clinical, biochemical and cranial magnetic resonance imaging data of six pediatric patients with L-2-hydroxyglutaric aciduria. All the children have the same ethic origin and lived in the northern area of Portugal. Our findings reinforce the described phenotype of this rare metabolic disease with mental deficiency, severe cerebellar dysfunction, mild extrapyramidal and pyramidal symptoms, progressive macrocephaly and seizures. Magnetic resonance imaging revealed subcortical leukoencephalopathy, cerebellar atrophy and signal changes in the putamina and dentate nuclei. These were similar to those of the previous reports in all patients. The urinary excretion of L-2-hydroxyglutaric acid was variably increased in all patients. The other persistent biochemical abnormality was hyperlysinemia. We have found a strong correlation between the severity of the clinical manifestations and the extension of the lesions in the neuroimaging studies. There was no correlation between the clinical findings and the amount of urinary excretion of L-2-hydroxyglutaric acid. We report the second case in the literature of a cerebral thalamic tumor in L-2-hydroxyglutaric aciduria; neuropathological examination of the surgical biopsy demonstrated a diffuse fibrillary astrocytoma.

2-Hydroxyglutaric aciduria: a case report on an infant with the D-isomeric form with review of the literature.

We report on an infant with D-2-hydroxyglutaric aciduria, who presented with severe seizures and developmental delay. We reviewed the literature for 2-hydroxyglutaric aciduria and found six other patients with the D-isomer and 24 patients with the L-isomer. Although the clinical spectrum of this inborn error of metabolism is variable, the clinical course of the D-form seems to be more severe than this of the L-form.

Congenital non-progressive encephalopathy and deafness with intermittent episodes of coma and hyperkynureninuria.

Six of nine children born from first-cousin parents presented with the same clinical picture: non-progressive congenital encephalopathy with marked hypertonia resembling the stiff-baby syndrome, delayed milestones, mental deficiency and congenital deafness. Rare, usually reversible, episodes of sudden worsening of the neurological status, with progressive loss of consciousness and increase of hypertonia, occurred spontaneously or during febrile illnesses. During these periods, and sometimes on other occasions, transitory renal dysfunction was observed (nephrotic syndrome and/or tubular abnormalities). Death occurred before age 2 years in 4 patients; 2 are still alive (10 and 13 years old). Electrophysiological, biological and enzymatic investigations remained negative, particularly those concerning mitochondrial and peroxisomal metabolism. The only biochemical anomaly was a massive hyperkynureninuria, seen only during the periods of coma (up to 213 mumol/mmol creatinine; normal < 10) and after an intravenous protein loading test. This suggests an anomaly of tryptophan metabolism which has not been reported up to now.

Identification of the D-enantiomer of 2-hydroxyglutaric acid in glutaric aciduria type II.

We determined the optical isomer of the 2-hydroxyglutaric acid (2HG) that was elevated in the urine of five Japanese children with a mild form of glutaric aciduria type II (GA2), caused by a deficiency of electron transfer flavoprotein (ETF) or ETF-ubiquinone oxidoreductase (ETF-QO). The D- and L-enantiomers of 2HG were separated by capillary gas chromatography with a combination of (S)-(+)-2-octanol derivatization and chromatography on a DB-1 column. The isomer that was elevated in GA2 patients was predominantly the D-enantiomer, an observation that may serve as an additional marker for the biochemical diagnosis of GA2. D-2HG dehydrogenation, but not L-2HG dehydrogenation is apparently blocked in GA2. A specific D-2HG dehydrogenase or D-2HG-CoA dehydrogenase may be metabolically linked to ETF and ETF-QO in the mitochondria.

[An enteral modular formula in dibasic amino aciduria]. / Fórmula modular enteral en aminoaciduria dibásica.

Lysinuric protein intolerance (LPI) or dibasic amino acid aminoaciduria is an unusual metabolic illness which, in countries where it is most common, affects one individual for every 60,000-80,000 births, and which is characterised by the inability to transport dibasic amino acids to the interior of the different cells of the organism. This paper sets out the design for an enteral modular formula for a pediatric patient very probably suffering from LPI. The formula has a very limited protein content, and incorporates L-citruline, a non-proteinogenic amino acid which intervenes in the urea cycle.

Enzyme reactor for urinary acylcarnitines assay by reversed-phase high-performance liquid chromatography.

An immobilized enzyme reactor, made up acylcarnitine hydrolase, carnitine dehydrogenase and diaphorase in sequence, was developed for the sensitive and selective determination of urinary free and individual acylcarnitines by a reversed-phase high-performance liquid chromatography. A 100-microliter urine sample was directly injected onto the TSKgel ODS 80Ts column and eluted by a step-gradient procedure. The eluent was mixed with the substrate solution of beta-NAD+ (1.0 mmol/l), resazurin (25 mumol/l) and Tris acetate (0.2 mol/l, pH 9.0). The mixture was passed through the immobilized enzyme reactor at 40 degrees C. Acylcarnitines were hydrolyzed and the converted to rezorufin which was measured by monitoring the fluorescence intensity at lambda EX = 560 nm and lambda EM = 580 nm. Free, acetyl-, glutaryl-, propionyl-, butyryl-, isobutyryl-, valeryl- and isovalerylcarnitine were determined within 55 min with detection limits (< 1 mumol/l) and within-run and day-to-day imprecision (C.V. < 6%). Free, acetyl- and isobutyrylcarnitine were found in normal urine. On the other hand, propionylcarnitine was detected in the urine of children with propionic aciduria and methylmalonic aciduria and multiple acylcarnitines were found in the urine of children with glutaric aciduria (type II).

Organic acidurias: a review. Part 2.

Laboratory findings are an essential part of the diagnostic approach to organic acidemias. In most organic acidemias, metabolism of glucose, ketone bodies, and ammonia is deranged primarily or secondarily, in addition to derangement of the acid-base balance. Hypoglycemia, lactic and/or ketoacidosis, and hyperammonemia of varying severity accompany the overt or compensated acidosis. In most instances, a definite diagnosis will be achieved by gas chromatography/mass spectrometry (GC/MS) studies of the urine. We detail the pattern of excreted organic acids in the major disorders. When the diagnosis reached by clinical and laboratory assessments is not conclusive, it must be supported by loading tests. We list the available methods of demonstrating the putative enzyme deficiency in the patient's cells and tissues. The majority of organic acidemias may be treated by limiting the source of or removing the toxic intermediary metabolite. We provide lists of available diets, supplements, and medications. In some instances, residual defective enzyme activity may be stimulated. We describe symptomatic management of the disturbed acid-base and electrolyte balance.

Aminoaciduria of severe trauma.

Plasma and urine levels of free amino acids were measured in 15 severely traumatized adult patients while they were receiving fluids free of calories and nitrogen. Endogenous plasma clearance and the relative rates of reabsorption of free amino acids from renal tubules were calculated. These data were compared with similar studies of eight control subjects. Multiple injury provoked distinct patterns of free amino acids in plasma and urine. Hypoaminoacidemia and hyperaminoaciduria were seen in severe trauma. There was a marked depletion of nonessential amino acids in plasma of trauma victims. In contrast, the urinary loss of all amino acids was increased 5-10 times. This enhanced loss in patients, however, represented only 2.1% of total N excreted compared with 0.7% in control subjects. Considerable variations were seen in the selectivity with which various amino acids were reabsorbed by renal tubules. This may partly be due to the abnormal pattern of amino acids presented to renal tubules.

Lack of D-amino-acid oxidase activity causes a specific renal aminoaciduria in the mouse.

Thin-layer chromatography and amino acid analysis showed that urine of mutant ddY/DAO- mice lacking D-amino-acid oxidase activity contained more serine, proline, alanine and methionine than that of normal ddY/DAO+ mice. Among these four, an increase in alanine was conspicuous. However, the urinary levels of 11 other amino acids and glucose were not different between the ddY/DAO- and ddY/DAO+ mice. Amino acid analysis showed that the plasma levels of serine, proline and methionine were not elevated in the ddY/DAO- mice, though a slight increase in alanine was observed. Genetic crosses showed that aminoaciduria and lack of D-amino-acid oxidase activity were concomitantly transmitted as a set through generations. These results indicated that the lack of enzyme activity caused a specific renal aminoaciduria. Whether this enzyme merely diminishes the D-amino acid load presented for reabsorption, or actually participates catalytically in the reabsorption process, remains undetermined.

Progress of renal dysfunction in inhabitants environmentally exposed to cadmium.

The reversibility of beta 2-microglobulinuria, glucosuria, and aminoaciduria was examined in 74 inhabitants (32 males and 42 females) over 50 yr of age, who lived in a cadmium-polluted area. The subjects participated in two examinations conducted just after the cessation of cadmium exposure and 5 yr later. All urinary parameters did not show reversible changes. During the 5 yr the geometric mean concentrations of beta 2-microglobulinuria, glucosuria, and aminoaciduria indicated significant increases in excretion. In cases where greater than 1,000 micrograms/g creatinine of beta 2-microglobulinuria was observed (at the time cadmium exposure ended), almost all individuals exposed to cadmium showed deterioration of beta 2-microglobulinuria, whereas in the case of less than 1,000 micrograms/g creatinine of beta 2-microglobulinuria, no significant changes were observed. The present study indicates that cadmium-induced renal dysfunction in individuals environmentally exposed to cadmium is irreversible.

Propionyl-CoA carboxylase deficiency in a patient with biotin-responsive 3-methylcrotonylglycinuria.

The abnormal metabolites 3-hydroxypropionic acid (1.6-4.0 mg/day) and methylcitric acid (3.7-5.8 mg/day) were identified and quantitated in the urine of a patient in whom biotin-responsive 3-methylcrotonylglycinuria and deficiency of 3-methylcrotonyl-CoA carboxylase had previously been documented. The level of excretion of these metabolites was in the lower range of those found in patients with propionic acidemia in whom there is a deficiency of propionyl-CoA carboxylase. The activity of this enzyme in fibroblasts derived from the patient and grown in media low in biotin was 4% of normal. This is the range of patients with propionyl-CoA carboxylase deficiency. Documented deficiency in this patient of two carboxylase, both of which contain biotin, suggests that the primary defect is in the metabolism of biotin.

Beta-aminoaciduria in patients with Burkitt's lymphoma.

The massive amounts of beta-aminoisobutyric acid (beta-AIBA) in the urine of Burkitt's lymphoma patients were measured along with other alpha-amino acids and beta-alanine present in normal and decreased levels. The ratios of the amount of beta-AIBA to beta-alanine, in mumoles/kg urine collected in 24 hours, were elevated for all patients. The degree of elevation of beta-AIBA excretion and the ratio of the two beta-amino acids appeared to be related to the amount of tumor mass present. These analyses may have possible value in monitoring patients with Burkitt's lymphoma during their disease course.

Renal handling of diamino acids in lysinuric protein intolerance.

Lysinuric protein intolerance (LPI) is a rare recessively inherited disease in which one of the fundamental physiological defects is in the mechanism by which diamino acids are transported by the kidney. The purpose of the present studies was to examine that mechanism in four controls and seven patients with LPI. Two types of studies were conducted. In the first set, the renal handling of l-arginine and l-ornithine was evaluated by gradually increasing the plasma concentration of each of these amino acids by constant infusion techniques. In the second set of studies, the possible existence of competitive inhibition between l-arginine, l-ornithine, and l-lysine was examined. In the control subjects, there was almost complete reabsorption of arginine and ornithine, with increases in their filtered loads to 50-100 times normal. With further increases in the filtered loads of these amino acids, there was a gradual decrease in their fractional reabsorption. Mutual competitive inhibition was suggested by the observation that an increase in the filtered load of one diamino acid was associated with a decrease in the reabsorption of the other two. In LPI, the fasting plasma diamino acid concentrations were significantly lower than in the controls. With low filtered loads, the fractional reabsorption of the diamino acids was clearly below normal. This defect diminished with higher loads. A stepwise increase in the plasma concentration of one diamino acid resulted in a biphasic response. Initially, net tubular secretion of the other diamino acids was noted, but later was followed by return to net absorption. When two diamino acids were infused simultaneously, net absorption of both took place, though less efficiently than in the controls. We conclude that the renal reabsorption mechanism is defective in patients with LPI. With low normal filtered loads, there is increased fractional excretion of all three diamino acids resulting in low serum concentrations of these compounds. However, at higher artificially elevated concentrations of diamino acids, the capacity of the renal transport system in these patients appears normal.