The potassium content of normal and some pathological human bloods

Our interest in the potassium content of human blood was aroused some time ago by the observation of Smillie 1 that poisoning may result from the administration of potassium salts to nephritic patients, and later confirmed in experimental uranium nephritis.

Observations on the potassium content of serum and whole blood have been made in fifteen cases, including four normal subjects, several cases of nephritis with marked nitrogen retention and a few miscellaneous cases. The potassium estimation was carried out by the cobaltinitrite method of Drushel essentially as described by Myers 2 in 1909 for spinal fluid.

The results obtained for serum in the four normal cases were somewhat less than 20 mg. per 100 c.c. calculated as K, and for whole blood about 8 to 10 times this amount. In five cases of nephritis with marked nitrogen retention the figures for the serum varied from 10 to 19 mg., in one mild case the potassium was 28 mg. while in a case of double polycystic kidney 35 mg. were found. The potassium content of the whole blood in these cases ranged from 52 to 148 mg. with an average of 100 mg. per 100 c.c. In all of these cases there was an associated secondary anemia and the total solids were diminished. No significant variation was found in a case of pure hypertension or a case of diabetic coma. Figures obtained for whole blood in two cases of pernicious anemia were low owing to the diminution in the red cell content.

In general the potassium content of whole blood tends to vary directly with the red cell content and the percentage of total solids. The few observations reported on cases of nephritis with marked nitrogen retention do not appear to support the suggestion that possibly some of the symptoms of uremia are due to a potassium poisoning as a result of retention of this element.