The Equilibrium between Cerebrospinal Fluid and Blood Plasma

The administration of an active parathyroid extract causes the serum phosphorus to fall and the serum calcium to rise (1-4). Although the effect of parathyroid injections on the serum calcium and serum phosphorus is very marked, the serum proteins remain unchanged (3) ; with normal parathyroid activity the serum calcium varies directly with the serum protein (5,6). Merritt and Bauer (7) have observed a similar relationship between the calcium of the cerebrospinal fluid and the serum protein. The variations of the serum calcium at different levels of parathyroid activity have been thoroughly studied but very little is known concerning the calcium content of other body fluids in these various stat,es. It is our purpose to report the relation of the serum calcium to cerebrospinal fluid and aqueous humor calcium at varying levels of parathyroid activity. The methods used have been previously described (7).