Pubmed literature search.
SETTING: KEY MESSAGES: Patients with
APRT deficiency or
primary hyperoxaluria may develop
ESRD as a result of crystalline nephropathy. In the absence of diagnosis and adequate management, the disease is likely to recur after
kidney transplantation, which often leads to rapid loss of renal allograft function.
Primary hyperoxaluria, but not
APRT deficiency, becomes a systemic disease at low GFR with
oxalate deposition leading to malfunction in non-renal organs (systemic
oxalosis). We suggest that these diagnoses should be considered in patients with low glomerular filtration rate (GFR) and a history of
kidney stones. In
APRT deficiency, stones may be confused with
uric acid stones, unless specialized techniques are used (infrared spectroscopy or X-ray crystallography for urinary crystals or stone analysis; Fourier transform infrared microscopy for crystals in kidney biopsy). Where these are unavailable, and for confirmation, the diagnosis can be made by measurement of
enzyme activity in red blood cell lysates or by genetic testing. In patients with
primary hyperoxaluria, levels of urinary and plasma
oxalate; and the presence of nearly pure
calcium oxalate monohydrate in stones, which often also have an unusually pale colour and unorganized structure, increase diagnostic suspicion. Molecular genetic testing is the criterion measure. Lifelong
allopurinol therapy, with high fluid intake if appropriate, may stabilize kidney function in
APRT deficiency; if
ESRD has occurred or is near, results with
kidney transplantation after initiation of
allopurinol are excellent. In
primary hyperoxaluria recognized before
ESRD,
pyridoxine treatment and high fluid intake may lead to a substantial decrease in urinary
calcium oxalate supersaturation and prevent
renal failure. In non-responsive patients or those recognized later in their
disease, liver transplantation cures the underlying defect and should be considered when the GFR falls below 30 ml/min/1.73 m(2); in those which or near
ESRD,
liver transplantation and intensive dialysis before
kidney transplantation may be considered to reduce the total body
oxalate burden before
kidney transplantation.
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