Objective: To measure the blood concentrations of total and ionized serum magnesium in feline renal transplant recipients and to determine if there was a correlation between these concentrations and the development of neurological disorders after renal transplantation.
Study design: Prospective clinical study.
Animals: Fourteen client-owned cats undergoing renal transplantation as a treatment for renal failure. Ten healthy adult cats were used to establish normal electrolyte concentrations.
Methods: Total and ionized serum magnesium as well as potassium and ionized calcium concentrations were measured in 14 renal transplant recipients at five intervals: preoperatively; immediately postoperatively; and 24, 48, and 120 hours postoperatively. The mean values from all 14 cats over each time interval were compared with the normal range. The serum concentration of these electrolytes, particularly magnesium, was evaluated in relation to the occurrence of neurological complications.
Results: Ninety-four percent of all ionized serum magnesium concentrations measured in clinical patients were below normal. Ninety percent of all total serum magnesium concentrations were within the normal range, and no cats had abnormally low total serum magnesium concentrations at any time. All clinical patients were hypocalcemic at all intervals. Sixty-six percent of all serum potassium concentrations were below normal. One cat in the study group experienced neurological problems, including seizures, in the immediate postoperative period. The signs appeared to be related to hypertension and responded to appropriate therapy. All electrolyte concentrations in this cat, including ionized magnesium, were within the same range of values as other clinical patients.
Conclusions: Ionized serum magnesium concentrations are decreased in feline renal transplant recipients in the perioperative period; however, hypomagnesemia would not appear to be directly related to the development of neurological disorders. None of the study patients were hypomagnesemic when total serum magnesium concentrations were measured over the same intervals. In addition, ionized serum calcium concentrations and serum potassium concentrations are below normal in the perioperative period.
Clinical significance: The specific clinical significance of these abnormalities is unknown. It is possible that the profound weakness and depression that is commonly seen in feline renal transplant recipients in the immediate postoperative period may be improved by supplementation with these electrolytes. Further work is needed to understand the implications of these abnormalities.