PRACTICAL APPLICATIONS OF THE SIMULTANEOUS DETERMINATION OF OXYHÆMOGLOBIN AND METHÆMOGLOBIN CONCENTRATIONS

SUMMARY Simple modifications of existing methods have been described in detail, to allow simultaneous determination of the concentrations of oxyhæmoglobin, methæmoglobin and “ intact ” hæmoglobin (oxyhæmoglobin plus methæmoglobin) in samples of blood. Both in vitro and in vivo , application of phenylhydrazine was found to cause preponderance of “ total ” hæmoglobin as determined by the cyanmethæmoglobin method over “ intact ” hæmoglobin measured by the method described. In the course of the methæmoglobin reduction test of Brewer et alii (1960), some destruction of “ intact ” hlemoglobin was usually observed in normal infants, children and adults. Greater loss of “ intact ” hæmoglobin occurred on testing an adult female with hæmoglobin H, two children with acute lead poisoning, and a new‐born infant and two adults with hæmatological manifestations following exposure to aromatic compounds. Increased propensity to destruction of “ intact ” hæmoglobin could not be detected in cord erythrocytes from normal infants, or in female children and adults with intermediate degrees of glucose‐6‐phosphate dehydrogenase deficiency. Susceptibility to loss of “ intact ” hæmoglobin appeared to be decreased in glucose‐6‐phosphate dehydrogenase‐deficient males. In normal subjects, no decline in the concentration of “ intact ” hæmoglobin took place if either nitrite or methylene blue was excluded from the incubation mixture. It is suggested that “ intact ” hæmoglobin determination might well be adopted to indicate the level of potentially‐functional hæmoglobin in the peripheral blood of patients suspected of circulating non‐functional pigments. In addition, application of this determination to the methæmoglobin reduction test should provide useful information concerning the stability of hæmoglobin under redox stress.