Methemoglobin

Abstract

The conversion of hemoglobin to methemoglobin by various chemical compounds and drugs has been reported repeatedly. Methemoglobin, so produced, has been held responsible for the toxic symptoms associated with its presence in the blood stream. However, there is little conclusive evidence that methemoglobin is the single causative factor in such toxemias. Methemoglobin may be a secondary factor in the chain of events associated with its presence in the blood stream.

The present work was undertaken to ascertain whether or not methemoglobin could be detected in the blood of normal persons, and to establish its normal range of concentration if it could be shown to be present. It was felt that either an affirmative or a negative answer to this question would have some bearing upon the problem of correctly interpreting the role of methemoglobin in pathologic conditions. If methemoglobin is a constituent of blood in normal persons, even in small concentrations, the view that it, in itself, is not toxic, and that its presence in higher concentrations in pathologic conditions is secondary to other factors which are responsible for the toxic symptoms, would gain support.

Experimental. Determinations were made upon two groups: (A) One hundred patients were selected at random from the wards of the Department of Medicine of the University of Iowa Hospital. No degree of selection was exercised other than to exclude those patients who were receiving sulfa drugs or other recognized methemoglobin-formers. The distribution in terms of sex was about 3 males to one female. The ages of the patients ranged from 7 to 78 years; no one age group predominated. A wide range of diseases was represented in order to rule out the possibility that methemoglobinemia was part of any given pathologic condition.