MEASUREMENT OF BLOOD-VOLUME AND RED-CELL MASS - REEXAMINATION OF CR-51 AND I-125 METHODS

Comparison of results of red cell mass (RCM) measurement by Cr-51 and I-125 methods in 119 patients showed virtual equivalence. Both methods have an acceptable coefficient of variation (CV) that is <5%. The I-1 25 method is simpler and much less expensive. Unrealistically narrow ' 'normal ranges'' for RCM are likely to lead to misdiagnosis of polycyt hemia vera. Upper normal limits of 39 mL/kg (males) and 32 mL/kg (fema les) are consistent with originally published data in normal persons; use of these limits as criteria would reduce the risk of misdiagnosis. No cases of ''stress erythrocytosis'' or Gaisbock Syndrome were encou ntered among the 119 cases reviewed.