ORIGINAL PAPERS

ELEVATION of blood magnesium to excess produces coma. ' Elevation of blood magnesium in moderation produces drowsiness. This sedative effect is applied therapeutically in the control of uraemic 2 and eclamptic 3 con-vulsions by intravenous magnesium sulphate. The converse of this, depression of blood magnesium, produces para-thyroid tetany. The latter has been developed experimentally in rats 4 on diets deficient in magnesium and may occur clinically with low blood magnesium.5 Nevertheless, there is no change in magnessemia after removal of the parathyroid glands in animals.6 Convulsions with hypomagnessemia have been described in other conditions, such as chorea and pneumonia.5 Hirschfelder 5 recently reported 10 patients with low blood magnesium, who suffered from convulsions or muscular twitchings. Four of these patients had kidney lesions. After single 20 to 25 gm. doses of Epsom salt were administered by mouth to these four, the magnesium in the plasma rose almost to double the normal concentration within four to six hours, and the twitch-ings or seizures subsided. Hirschfelder concluded that convulsions are relieved by oral magnesium sulphate in patients with renal insufficiency. METHOD In view of these findings the blood magnesium in a series of patients subject to epileptiform seizures was studied at St. Elizabeth's Hospital. A normal value for magnesium in blood was first established. Colorimetric estimation on Folin-Wu blood filtrate with titan yellow as the specific reagent, a modification of the Hirschfelder and Serles technique,7 was used. In a group of 15 controls findings ranged from 2-9 to 4 0 mgm. of magnesium per 100 c.cm. of whole blood. The controls were individuals most of whom had never taken a dose of Epsom salt or milk of magnesia, the remainder not having had either cathartic for six months prior to the estimations. The