Which type of specimen is primarily collected using a grey-top tube?

The grey-top tube is specifically designed for the collection of specimens that require glucose testing, particularly glucose tolerance tests and lactic acid testing. This tube contains sodium fluoride, which acts as a glycolytic inhibitor, preventing the breakdown of glucose by red blood cells after the sample is drawn. This property is crucial for obtaining accurate measurements of glucose levels, especially in tests where precise monitoring of glucose metabolism is required.

In the case of lactic acid testing, preventing glycolysis is essential as it helps maintain the integrity of the lactic acid levels in the sample. If glycolysis occurs, it could lead to artificially low readings, thus skewing results. Therefore, the grey-top tube's role in preserving glucose and lactic acid levels makes it the appropriate choice for tests focused on these substances.

Other types of specimens utilize different tube colors and additives tailored for specific tests, but for collections involving glucose and lactic acid, the grey-top tube is distinctive and indispensable.