Variations in Plasma Magnesium and Potassium in Epilepsy

McCollum and his collaborators,, and also Greenberg and Tufts have produced hyperirritability and convulsions in rats fed on a diet deficient in magnesium. Since we have found neuromuscular twitchings and convulsions in cases of clinical hypomagnesaemia, since McQuarrie believes that in epilepsy there is a “leakage of potassium” through the cell membrane, and since Hirschfelder has shown that potassium salts can antagonize the narcotic action of magnesium, we have investigated the plasma magnesium and potassium in clinical epilepsy. We determined magnesium by the method of Hirschfelder, Serles and Haury and potassium and calcium by those of Kramer and Tisdall., Total magnesium 1.7 mg. Mg or below 100 cc. plasma and ultrafiltrable Mg 0.7 or below were regarded as low; K above 30 mg. was regarded as high. In epileptics whose plasma was collected during or just before convulsions we found the following deviations from normal: In 5 cases of status epileptics low magnesium (1.2 to 1.7 mg.) occurred in 4, high potassium (35 to 68.5 mg.) occurred in 5, high potassium/magnesium ratio occurred in 5. In 13 epileptics with very severe convulsions, low magnesium (1.3 to 1.7 mg.) occurred in 9, high potassium (31.7 to 63.6 mg.) occurred in 6, high potassium/magnesium ratio occurred in 13. In 12 moderately severe epileptics low magnesium (1.6 to 1.7 mg.) occurred in 3, high potassium (31.6 to 52.8 mg.) occurred in 8, high potassium/magnesium ratio occurred in 11. In 5 epileptics with mild convulsions, low magnesium (1.6 to 1.7 mg.) occurred in 2, high potassium (31.7 to 40.2) occurred in 3, high potassium/magnesium ratio occurred in 4.