Abstract
In our earlier work 1 with the Hamilton and Schwartz 2 test for parathyroid hormone, we used 2 breeds of rabbits, raised by ourselves; a black and white Dutch strain and a gray Belgian strain, which included some albinos. All these rabbits gave a positive test when injected with 10 Hansen units of parathormone per kg. In a few instances injection with as little as 4 units per kg resulted in a positive reaction. Similar responses were given by hybrids of these 2 strains. (The H. and S. test depends upon the fact that successive feedings of CaCl2 result in smaller and smaller rises in serum Ca, so that after the 3rd or 4th administration of 100 mg of Ca as CaCl2 normal rabbits will show a rise of serum Ca of less than 1.2 mg per 100 cc, whereas if more parathyroid hormone than that normally circulating is present, a greater rise of serum Ca results, roughly proportional to the quantity of hormone administered.)
When New Zealand white or chinchilla rabbits were used for this test, it was found they were less sensitive than the Dutch or Belgian breeds. They required an injection of 20 or 30 units of parathormone per kg to react positively. Six chinchillas and 4 New Zealand whites all gave negative reactions when injected with 10 units per kg. With a dose of 20 units per kg of parathyroid extract only 3 of 5 chinchillas and 1 of 3 New Zealand white rabbits reacted positively, while 2 of each of these strains gave positive reactions only with a dose of 30 units per kg.
It is advisable, therefore, to determine the sensitivity of rabbits to be used for the Hamilton and Schwartz test.
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