Which disease is characterized by a low protein level?

Marasmus is a form of severe malnutrition characterized primarily by inadequate caloric intake, resulting in significant weight loss and muscle wasting. One of the key features of marasmus is that it leads to low levels of total protein in the body, as there is not enough dietary protein to support the body's needs. This condition is often a result of chronic energy deficiency, where the body primarily utilizes its own muscle and fat stores for energy, leading to a decrease in both body mass and protein levels.

In contrast, the other diseases listed can have different impacts on protein levels. For example, in hepatitis B, while liver function can be impaired and affect protein synthesis, it is not primarily characterized by low protein levels. Amyloidosis involves the deposition of amyloid protein in tissues and can lead to varying protein levels, but it does not inherently result in low protein like marasmus does. Multiple myeloma is a cancer of plasma cells that can lead to increased levels of certain proteins in the blood, particularly monoclonal proteins, and may not present with low protein levels overall.