The Local Blood Flow in Human Bone Marrow in Leukemia and Neoplastic Diseases as Determined by the Clearance Rate of Radioiodide (I131) 1

Although considerable information has been obtained on the rate of blood flow in many or- gans (1), few data have been reported on the blood flow in human or animal bone marrow (2).The neglect of this aspect of marrow physiology is probably due to the technical difficulties en- countered in gaining access to the blood vessels of this diffuse organ in the intact animal or man.The extensive application of the radioisotope clearance technique described by Kety (3, 4) for the estimation of the regional circulation in muscle, liver, subcutaneous tissues, brain tissue, and skin (4-10) suggested its use as a clinically applicable method for the evaluation of the effec- tive local blood flow in the human bone marrow.This method is based on the premise that if a diffusible tracer substance is introduced into a tissue its clearance or removal is a function of all possible factors contributing to the local blood flow at the site of injection.In the present study, the relative rates of clear- ance of II8' from the bone marrow were determined in patients with various malignant dis- eases and leukemia.The radioiodide was in- jected into the bone marrow through a standard bone marrow needle, and the rate of disappear- ance of the isotope was measured with a Geiger-Mueller counter.In addition, simultaneous de- terminations of I'll clearance rates from the gas- trocnemius muscle were obtained for comparing the clearance rates obtained in the bone marrow 1 Presented in part at the Annual Meeting of Western Section of the American Federation for Clinical Re- search, Carmel, California, January 24, 1952.2Postgraduate Research Fellow, National Cancer In- stitute.with those found in an anatomically and physiologically different vascular bed.