Blood pressures, specific gravities of whole blood and the hematocrit values of more than 4000 volunteer donors (male 2900, female 1300) who visited The Tokyo Red Cross Blood Center from January, 1965 till December, 1966, ranging from 16 to 60 years old, were tested. The correlation between the specific gravities of whole blood by copper sulfate method and the hematocrit values was investigated. The results obtained were summarized as follows.
1. Blood pressure: The systolic blood pressure was higher in young people, both men and women, than the standard value of the Japanese reported by Watanabe in 1947, whereas the diastolic blood pressure was the same as the standard. It is noteworthy that the systolic blood pressure of young people became higher than at 20 years ago.
2. Specific gravities of whole blood: Specific gravities of whole blood lay around 1.) 57 in male and around 1.) 53 in female.
3. Hematocrit values: Hematocrit values obtained by using capillaries made of Panlite corresponded to the standard values, being 45% for male and 40% for female.
4. Some correlation existed between the specific gravities of whole blood and the hematocrit values. There was a tendency, however, that the latter showed a relatively wide range against one definite value of the former. For example, the hematocrit values of blood samples which have the same specific gravity of 1.052 had a range from 32% to 48%.
5. Judging from the specific gravities persons whose values are 1.051 or lower cannot donate blood. Judging from the hematocrit values, however, 89.3% and 62.5% of persons whose specific gravities are 1.051 and 1.050 respectively, can donate their blood for transfusion.
6. According to our opinion exclusion of prospective donors on the basis of specific gravities of whole blood does not seem superior than on the basis of hematocrit values.
