Abstract
As a series of studies on the seasonal variation of physiological functions, protein-bound iodine in serum was determined along with the BMR. An experimental period of one year commencing in June 1969 included 10 Japanese and 9 Americans the same as stated in the first report. Conclusions are as follows:
1) As for the annual mean value of serum PBI, there was no significant difference between Japanese and Americans, however, both groups showed significant seasonal variations to be low in summer and high in winter.
2) As for Japanese, serum PBI level was higher in the cold winter, but it was noted to be at a high level in Americans during the cool autumn season rather than cold winter season. This is attributed to utilized warmer room temperatures than that of Japanese, as mentioned in the first report on BMR.
3) Positive correlation between PBI and BMR on both groups was found to be significant.
4) Regarding relationship to the mean external temperature, PBI showed higher values in autumn than in spring under the same external temperatures. Furthermore it was found that the rate of PBI varied earlier and higher than that of BMR according to seasonal changes.
