Which test should be collected in a royal blue tube top?

The correct choice, which is the test that should be collected in a royal blue tube top, is aluminum. Royal blue tubes are specifically designed for trace metal analysis, which is crucial for ensuring that contaminants do not interfere with the test results. Aluminum testing is particularly sensitive to contamination, thus necessitating the use of this dedicated tube that minimizes exposure to other metals.

While lead is often associated with testing in royal blue tubes as well, aluminum is the more accurate answer in this context. The royal blue top tube's special treatment prevents metallic contamination, making it ideal for collecting samples for aluminum testing.

The other tests listed, such as calcium and sodium, do not require collection in a royal blue tube, as they are typically collected in standard tubes designated for biochemical assays. Therefore, the specific design and purpose of the royal blue tube make it the appropriate choice for obtaining accurate aluminum levels in blood samples.