Management of primary hyperoxaluria: efficacy of oral citrate administration

The prognosis of primary hyperoxaluria (PH) is not only related to endogenous oxalate production and the response (if any) to pyridoxine (in type I), but is greatly influenced by extrarenal factors like dehydration. The earlier the diagnosis of PH, the better the chances of improving the prognosis in individual patients. Measures to enhance the solubility of calcium oxalate are important. Besides ensuring at all times a generous fluid intake (>2 l/m²), administration of alkali citrate (0.15 g/kg), which has not been advocated so far in PH, appears very promising. We studied the effect of sodium citrate in six patients with PH. Mean urinary citrate excretion (mmol/day per 1.73 m²) without oral citrate was very low (0.57) and rose to 2.49 with citrate administration. This was accompanied by a significant decrease in the calcium oxalate saturation (calculated by equil 2) from 11.7 to 6.9 (P<0.05). Treatment in five patients over 10–36 months resulted in improved (1) or stabilized (4) renal function and reduced passage of stones. Additional measures include restriction of salt and of oxalate-rich food. We conclude that long-term administration of alkali citrate is beneficial in patients with PH.     

Oxalose Typ I im Kindesalter — Beobachtungen im Rahmen der terminalen Niereninsuffizienz beim Kind

Summary The difficulties of biochemical diagnosis in children and in chronic renal failure are discussed in detail, as well as the development of diagnostic and therapeutic possibilities in recent years, exemplified by 4 cases.Excretion of oxalate (and glycolate) may be incorrectly assumed to be normal with: a) uncritical application of the method of measurement, b) disregard of the clearly lower oxalate excretion in children (values should be referred to m² of body surface), c) disregard of a decreased glomerular filtration rate (values should be referred to the creatinine clearance). With compromised renal function the excretion of oxalate and glycolate in primary oxalosis drops to normal whereas plasma values increase considerably. In this case the biochemical diagnosis is possible only by measurement of plasma values of glycolate and oxalate. Consequently, extensive extrarenal deposition of calcium oxalate crystals will, as a rule, become clinically manifest only after chronic renal failure has turned irreversible.In recent years, several therapeutic procedures, have been developed. They are of therapeutic significance for the early stages of the disease as well. Observing especially conditions renal transplantation or combined hepatorenal transplantation can be managed with a successful outcome.As the perioxisomal enzyme is activated only in the liver cells, an early liver transplantation as a definitive treatment by enzyme replacement may be the successful therapy in the future.

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Abkürzungen NI Niereninsuffizienz - KOF Körperoberfläche - NTP Nierentransplantation - AGT Alanin-Glyoxalat-Aminotransferase     

Combined Kidney and Intestinal Transplantation in Patients With Enteric Hyperoxaluria Secondary to Short Bowel Syndrome

Kidney transplantation is the treatment of choice for end‐stage renal disease whereas indications for intestinal transplantation are currently restricted to patients with irreversible small bowel failure and severe complications of total parenteral nutrition (mostly shortage and infection of venous accesses, major electrolyte disturbances and liver failure). Enteric hyperoxaluria is secondary to certain intestinal diseases like intestinal resections, chronic inflammatory bowel disease and other malabsorption syndromes and can lead to end‐stage renal disease requiring kidney transplantation. We report two patients suffering from renal failure due to enteric hyperoxaluria (secondary to extensive intestinal resection) in whom we elected to replace not only the kidney but also the intestine to prevent recurrence of hyperoxaluria in the transplanted kidney.     

Etiology of nephrocalcinosis in northern Indian children

This retrospective survey examines the etiology of nephrocalcinosis (NC) in 40 patients (26 boys), over an 8-year period. The median age at onset of symptoms and presentation was 36 months and 72 months, respectively. Clinical features included marked failure to thrive (82.5%), polyuria (60%) and bony deformities (52.5%). The etiology of NC included distal renal tubular acidosis (RTA) in 50% patients and idiopathic hypercalciuria and hyperoxaluria in 7.5% each. Other causes were Bartter syndrome, primary hypomagnesemia with hypercalciuria, severe hypothyroidism and vitamin D excess. No cause for NC was found in 12.5% patients. Specific therapy, where possible, ameliorated the biochemical aberrations, although the extent of NC remained unchanged. At a median (range) follow up of 35 (14–240) months, glomerular filtration rate (GFR) had declined from 82.0 (42–114) ml/min per 1.73 m² body surface area to 70.8 (21.3–126.5) ml/min per 1.73 m² body surface area (P = 0.001). Our findings confirm that, even with limited diagnostic facilities, protocol-based evaluation permits determination of the etiology of NC in most patients.     

Detection of AGXT gene mutations by denaturing high-performance liquid chromatography for diagnosis of hyperoxyluria type 1

Primary hyperoxaluria type 1 is an autosomal recessive disorder of glyoxylate metabolism, caused by a deficiency of alanine:glyoxylate aminotransferase, which is encoded by a single copy gene (AGXT). The aim of this research was to standardize denaturing high-performance liquid chromatography, a new, sensitive, relatively inexpensive, and automated technique, for the detection of AGXT mutation. Denaturing high-performance liquid chromatography was used to analyze in blind the AGXT gene in 20 unrelated Italian patients with primary hyperoxaluria type 1 previously studied by other standard methods (single-strand conformation polymorphism analysis and direct sequencing) and 50 controls. Denaturing high-performance liquid chromatography allowed us to identify 13 mutations and the polymorphism at position 154 in exon I of the AGXT gene. Hence the method is more sensitive and less time consuming than single-strand conformation polymorphism analysis for the detection of AGXT mutations, thus representing a useful and reliable tool for detecting the mutations responsible for primary hyperoxaluria type 1. The new technology could also be helpful in the search for healthy carriers of AGXT mutations amongst family members and their partners, and for screening of AGXT polymorphisms in patients with nephrolithiasis and healthy populations. Received: 18 January 2001 / Accepted: 7 May 2001