Which trace element is present in current PN additives at greater than five times the current estimated requirement?

Which trace element is present in current PN additives at greater than five times the current estimated requirement?

• A. Manganese
• B. Zinc
• C. Copper
• D. Selenium

Answer: (A)

The key idea is that trace elements in parenteral nutrition are dosed to meet needs, but some are supplied well above current requirements due to historical formulations and safety concerns about deficiency. Manganese is routinely included in PN additives at levels that exceed the current estimated requirement by more than fivefold. This reflects the fact that manganese is store-accumulating and excretion is primarily bile-dependent, so excess can build up, particularly in patients with impaired bile flow or liver dysfunction. While zinc, copper, and selenium are essential and dosed to meet needs, they are not typically present at such a large multiple of the requirement in standard PN. Therefore, manganese is the trace element most commonly present in PN additives at greater than five times the current estimated requirement.

The key idea is that trace elements in parenteral nutrition are dosed to meet needs, but some are supplied well above current requirements due to historical formulations and safety concerns about deficiency. Manganese is routinely included in PN additives at levels that exceed the current estimated requirement by more than fivefold. This reflects the fact that manganese is store-accumulating and excretion is primarily bile-dependent, so excess can build up, particularly in patients with impaired bile flow or liver dysfunction. While zinc, copper, and selenium are essential and dosed to meet needs, they are not typically present at such a large multiple of the requirement in standard PN. Therefore, manganese is the trace element most commonly present in PN additives at greater than five times the current estimated requirement.