Iodine and Pulse Rate of Normal Individuals.

Abstract

The belief exists and the statement has been made that the administration of iodine to normal individuals will produce slowing of the pulse rate. Since no satisfactory information upon this point could be obtained from text-books upon pharmacology and materia medica, it was determined to ascertain the effect on the normal pulse of ingesting the same amount of iodine as we have been administering to patients with Graves' disease.

Twelve internes, laboratory workers and physicians, without signs or symptoms of thyroid disease, and with normal basal metabolic rates, volunteered as subjects. There were 4 females and 8 males, 22 to 36 years of age. The pulse rate before arising in the morning was recorded for 10 days to ascertain the normal for each individual. On the next succeeding 10 days Lugol's solution (10 drops) was taken once daily before breakfast. During this period and continuing through another period of 10 days after taking iodine the pulse rate was recorded as in the preliminary period. Records of the mid-day and evening pulse rate were also obtained but these proved to be so variable, depending upon the subjects' activity, that only the mean readings of the morning (basal) pulse are shown in Table I.

There was very slight increase in the pulse rate in 7, no change in 3 and a slight decrease in 2 cases. In no individual case was any marked effect noted, neither do the means for each sex show significant change in value. The general tendency of the means for all subjects is toward an increase, but the changes are inconsequential, when tested by the criterion that the difference in two values to bear significance must be greater than 3 times the probable error. 1