What tests are commonly associated with gray tubes?

The common association of gray tubes with specific tests stems from the additives they contain and the types of samples they are designed to handle. Gray-topped tubes typically contain potassium oxalate and sodium fluoride. Potassium oxalate acts as an anticoagulant, while sodium fluoride serves as a glycolytic inhibitor, which is crucial for certain tests that measure substances in the blood, where glucose breakdown can skew results.

Among the tests listed, oral glucose tolerance test (OGTT), lactic acid, and ethanol (ETOH) levels are indeed correctly associated with gray tubes. The OGTT is specifically used for diagnosing diabetes and requires accurate glucose measurements that could be affected by glycolysis if a standard tube were used. The lactic acid test also needs to be performed quickly to prevent glucose from being metabolized into lactic acid, and thus using a tube that inhibits glycolysis is essential. Similarly, ethanol testing requires that the sample not be subjected to any metabolism, as this could lead to inaccurate results; therefore, gray tubes are preferred to stabilize the sample.

This understanding of the gray tube’s functionality clarifies why these specific tests are linked to this type of collection tube.