Hypermetabolic refers to the physiological state of having a greatly increased rate of metabolic activity. The impact of the hypermetabolic state on patient nutritional requirements is often understated or overlooked. Hypermetabolism typically occurs after significant insult to the body. In hospitals and institutions, the most common causes are infections, sepsis, burns, multiple trauma, fever, long-bone fractures, hyperthyroidism, prolonged steroid therapy, surgery and bone marrow transplants.
During the acute phase, the liver redirects protein synthesis, up-regulating certain proteins and down-regulating others. Measuring the serum level of proteins that are up- and down-regulated during the acute phase can reveal extremely important information about the patient's nutritional state. The most important up-regulated protein is C-reactive protein, which can rapidly increase 20- to 1,000-fold during the acute phase.