Question

Which of the following tests is not used to assess vitamin A status?

1: Plasma carotenoid level
2: Serum retinol concentration
3: Plasma transthyretin-retinol binding protein (TTR-RBP) concentration
4: Serum retinol binding protein (RBP) level

Answer 1

The plasma transthyretin-retinol binding protein (TTR-RBP) concentration is not typically used to assess vitamin A status; instead, plasma carotenoid level, serum retinol concentration, and serum retinol-binding protein (RBP) level are the common tests.

Step-by-step explanation:

The question asks which among the given tests is not used to assess vitamin A status. The tests listed are typically associated with the measurement of different components related to vitamin A in the body. To assess vitamin A status, the following are commonly used:

1. Plasma carotenoid level - Carotenoids are precursors to vitamin A and their levels can indicate vitamin A status.
2. Serum retinol concentration - This test measures the amount of retinol, a form of vitamin A, present in the serum.
3. Serum retinol-binding protein (RBP) level - RBP is a protein that binds to retinol, facilitating its transport in the blood.

The plasma transthyretin-retinol binding protein (TTR-RBP) concentration is not typically used as a standalone test for assessing vitamin A status, making it the correct answer. However, TTR (also known as albumin) does bind to RBP and can be related to vitamin A transport, it is not commonly measured for vitamin A status assessment.