THE HYPEREMIA AZT AND THE EVALUATION OF THE HYPEREMIA RAT UNIT OF CHORIONIC GONADOTROPIN*

Abstract

-Chorionic gonadotropin elicits an early ovary reaction (hyperemia reaction) in infantile [female] rats. The hyperemia reaction does not fluctuate if the reading is carried out at a fixed time after hormone injn. Large fluctuations are observed in the sensitivity. of the test if the time span is allowed to vary between 2 and 24 hrs. Maximum sensitivity is found at 10 hrs. when as little as 0.5 rat units is sufficient to elicit a hyperemic response. At 8 and 11 hrs., the hyperemia unit equals the rat unit. The hyperemia unit (HU) rises progressively when the time span is varied below or above 8 hrs. At 2 and 6 hrs., the HU is equal to 20 and 14 RU respectively. At 24 hrs., 1 HU is equal to 5 RU. The 24 hr. test is 4 times as sensitive as the 2 hr. test. The smaller reliability of the 2 and 6 hr. tests as compared to the 24 hr. test is explained by this finding. The hyperemia reaction of the ovary at 8 hrs. or less is pink. At 10 hrs. or more, the ovary reaction is a deep red similar to the color of spleen, kidney, or liver. Using the 24 hr. test, an accuracy of 99% and better in the diagnosis of pregnancy was obtained. Using the 2 and 6 hr. tests, error rates of 31 and 8% respectively were experienced. The 10 hr. test, which affords the maximum sensitivity, is recommended in the following special circumstances: examinations of toxic urine of which only small dosages can be injected into a test animal; cases involving suspicion of extra uterine pregnancy, when speed of detn. is a paramount consideration. Disadvantages of the 10 hr. test as a routine examination are its extreme sensitivity and inconvenient time arrangement. Hence, the most suitable method for routine use is the 18-24 hr. test.