Clinical and histologic features of primary oxalosis

Primary oxalosis should be considered in patients with multisystem disease of the kidneys, heart, peripheral vasculature, and skin. Crystalline deposits can lead to nephrolithiasis with kidney failure, complete heart block, peripheral vasospasm, and livedo reticularis, as in our patient. Crystals were first observed in the myocardial biopsy specimen and then identified as calcium oxalate in skin from an area of livedo reticularis.

Primary hyperoxaluria type I

Primary hyperoxaluria type I is a metabolic disorder caused by the deficiency of the peroxisomal alanine:glyoxylate aminotransferase. The disease is inherited as an autosomal recessive trait. The clinical course is outlined based on data from 330 published cases. Diagnostic cornerstones are clinical parameters, urinary excretion of oxalate and glycolate, and the determination of enzyme activity in liver tissue. Principles of conservative treatment, e.g. volume load and pyridoxine substitution, are described as well as experience with different modes of dialysis and transplantation. Kidney transplantation is associated with a high rate of recurrence of the original disease despite excellent management resulting in many instances in early graft loss. Liver transplantation offers the possibility to correct the metabolic defect and to prevent the progression of crystal deposition in the body.

[Primary hyperoxaluria]

Primary hyperoxaluria is a recessive hereditary disturbance of glyoxylate metabolism caused by deficiency of the liver enzyme, alanine glyoxylate transaminase. The main symptoms are recurrent renal stones, nephrocalcinosis and renal failure. In the advanced state, the disease is frequently complicated by osseous disease, vascular insufficiency and cardiac arrhytmias caused by deposits of calcium oxalate in the tissue. The prognosis is poor. No specific medical treatment exists. Dialysis is not effective and the results of renal transplantation is poor. Combined liver and renal transplantation correct the metabolic defect and the excretion of oxalate is normalised. Combined transplantation must be regarded as the optimal treatment of renal failure caused by PHO. The transplantation should be undertaken preferably before the creatinine clearance falls below 10-20 ml/min in order to avoid tissue deposits of calcium oxalate and excessive urinary excretion of oxalate during immediate post-transplantation period.

Primary bone oxalosis: the roles of oxalate deposits and renal osteodystrophy

Primary oxalosis is a rare congenital disorder. The excessive oxalate biosynthesis induces deposits in many organs, particularly in kidney and bone. The late onset of primary oxalosis is reported in a 50-year-old man. His chronic renal failure was treated by maintenance hemodialysis for 3 years. He then developed a diffuse bone disease with osteosclerosis and roentgenographic features of hyperparathyroidism. A parathyroidectomy was performed, with debatable improvement of bone lesions. Laboratory results and histologic and histomorphometric studies before and after parathyroidectomy suggest a double histopathogenetic mechanism for this bone disease: renal osteodystrophy and massive bone oxalate deposits. Such deposits may induce both a heterogeneous osteosclerosis with dense metaphyseal bands and histologic bone lesions similar to those of hyperparathyroidism. The crystalline deposits induce in the bone tissue a granulomatous macrophagic reaction. These macrophages are unable to phagocytize the crystals and may be involved in active bone resorption. Bone lesions of oxalosis occur in patients with chronic renal failure, and hyperparathyroidism has a worsening role.

Oxalate dynamics in chronic renal failure. Comparison with normal subjects and patients with primary hyperoxaluria

In order to separate the effect of oxalate retention in primary hyperoxaluria with renal failure from that of excessive oxalate synthesis and to determine the optimum time for renal transplantation in primary hyperoxaluria, we have studied a series of patients with different degrees of renal failure due to other causes. The results were compared with those obtained in studies on 8 patients with primary hyperoxaluria at different levels of residual overall renal function. In the patients with renal failure unrelated to primary hyperoxaluria, oxalate retention increases rapidly when the glomerular filtration rate (GFR) decreases below about 20 ml X min-1. These results suggest that the reduced renal excretory contribution to oxalate accumulation in primary hyperoxaluria would be expected to be particularly important in this range of GFR. In primary hyperoxaluria, oxalate retention occurs when GFR is only a little below the reference range and measures to remove oxalate from the body should be considered when the GFR falls below 40 ml X min-1 X 1.73 m-2, with a view to their introduction when the GFR is in the range 20-25 ml X min-1 X 1.73 m-2.