Which mechanism describes how Tc mebrofenin localizes in tissues?

• A. Secretion and absorption
• B. Phagocytosis
• C. Hepatocyte uptake and secretion
• D. Capillary filtration

Answer: (C)

Tc mebrofenin is a radiopharmaceutical that is primarily used in imaging the liver and biliary system. The correct answer, focused on the mechanism of localization in tissues, emphasizes the process of hepatocyte uptake and secretion.

Mebrofenin is designed to be taken up specifically by hepatocytes (liver cells) through a process that involves active transport mechanisms. Once inside the hepatocytes, it undergoes further processing and is secreted into the bile canaliculi, from where it eventually enters the bile ducts and can be visualized during imaging procedures targeted at assessing liver function or detecting biliary obstructions.

This targeted localization is crucial for evaluating liver function because it depends on the liver's ability to uptake and secrete substances. Hence, the effectiveness of mebrofenin in providing diagnostic information is largely due to this specific interaction with the liver's cellular mechanisms rather than general processes like phagocytosis or capillary filtration, which would not selectively localize the compound to the liver or biliary tract.