RT Journal A1 SMITH HP, ZIFFREN SE, OWEN CA, HOFFMAN GR T1 CLinical and experimental studies on vitamin k JF Journal of the American Medical Association JO Journal of the American Medical Association YR 1939 FD July 29 VO 113 IS 5 SP 380 OP 383 DO 10.1001/jama.1939.02800300010004 UL http://dx.doi.org/10.1001/jama.1939.02800300010004 AB It is our purpose in the present paper to discuss the bleeding tendency so often seen in patients having biliary fistulas or obstructive jaundice. In many of these patients death occurs from persistent hemorrhage. This hemorrhage may begin independently of known trauma, but usually it begins at operation or appears from the wound after operation. It is now known that the bleeding is due to abnormal lowering of the plasma prothrombin level and that in most cases the bleeding tendency can be relieved by vitamin K therapy. We wish to outline the experimental and clinical work on which this theory is based, and along with this we wish to describe, briefly, a simple method that we1 have recently devised for the recognition of the vitamin deficiency. With the aid of this test it is now possible to obtain information at the bedside regarding vitamin K requirements. It is also