Excessive myocardial calcinosis in a chronic hemodialyzed patient.

Secondary oxalosis in chronic hemodialyzed patients is caused by impaired renal excretion and inadequate removal of oxalic acid during hemodialysis. Ascorbic acid is a precursor of oxalic acid. We report a parathyroidectomized patient with chronic renal failure, on hemodialysis, who received over a period of several months a total dose of 91.0 g ascorbic acid i.v. The plasma oxalic acid level in this patient was 14-fold higher than in healthy persons. Increased oxalic acid synthesis from its precursor ascorbic acid may be responsible for hyperoxalemia, high content of oxalic acid in myocardium, aorta and lung, and calcium oxalate deposition in soft tissues. Application of high doses of ascorbic acid should be avoided in hemodialysed patients with chronic renal failure.