Consolidated Political Compass Test (CPCT) Practice Exam 2026 - Free CPCT Practice Questions and Assessment Guide

The gray tube is primarily used for collecting blood specimens for specific tests that require certain additives to prevent glucose metabolism and stabilize the sample. The additive used in the gray top tube is sodium fluoride, which acts as a glycolytic inhibitor. This means it prevents the breakdown of glucose by inhibiting the enzyme enolase, thereby preserving glucose levels in the blood sample during transport and storage.

The tests most commonly performed using specimens from the gray tube include those for alcohol levels, lactic acid, and glucose. Sodium fluoride ensures that glucose levels remain stable for accurate results during these tests, which is crucial for diagnosing conditions such as diabetes. These substances require precise measurements, as their levels can fluctuate rapidly if the sample is not properly preserved. Consequently, sodium fluoride is an ideal choice for tests where accurate glucose measurement is essential, making this choice correct.