From the Guidelines
A hypermetabolic state is a condition where the body's metabolism is significantly increased, resulting in higher energy expenditure and calorie burning, characterized by a catabolic response with altered energy production pathways and increased breakdown of proteins, fats, and carbohydrates. This state is often seen in response to acute injury, infection, or surgical insult, and is proportional to the magnitude, nature, and duration of the injury 1. The hypermetabolic phase is marked by:
- Elevated resting energy expenditure (REE), which can range from 77% to 139% of predicted energy expenditure in patients with acute pancreatitis 2
- Increased oxygen consumption
- Higher calorie burn at rest
- Accelerated breakdown of proteins, fats, and carbohydrates Common causes of hypermetabolism include severe burns, major trauma, sepsis, hyperthyroidism, and certain medications. The body enters this state as a stress response, attempting to heal or fight off infection. While temporary hypermetabolism can be part of normal healing, prolonged hypermetabolic states can lead to muscle wasting, weight loss, and other complications. Management of hypermetabolism typically involves:
- Increased caloric intake, often 1.5-2 times normal requirements
- High-protein diet to prevent muscle breakdown
- Careful monitoring of fluid and electrolyte balance
- Treatment of underlying cause (e.g., antibiotics for sepsis, thyroid medication for hyperthyroidism) Understanding hypermetabolism is crucial for proper patient care, especially in critical care settings, as it significantly impacts nutritional needs and overall recovery, with energy adequacy associated with lower mortality 1.
From the Research
Definition of Hypermetabolic State
A hypermetabolic state is a condition characterized by an increased metabolic rate, often observed in patients with sepsis, burn, or trauma 3. This state is associated with alterations in carbohydrate metabolism, including enhanced peripheral glucose uptake and utilization, hyperlactatemia, increased glucose production, depressed glycogenesis, glucose intolerance, and insulin resistance.
Characteristics of Hypermetabolic State
The hypermetabolic state is induced by the area of infection or injury, as well as by organs involved in the immunologic response to stress 3. It generates a glycemic milieu that is directed toward satisfying an obligatory requirement for glucose as an energy substrate. Hypermetabolism is also characterized by a considerable increase in resting energy expenditure and substantial whole-body catabolism 4.
Mechanisms of Hypermetabolic States
The mechanisms involved in hypermetabolism are not fully understood, but it is hypothesized that the adipose tissue plays a central role in the induction and persistence of hypermetabolism post-burn injury 4. Hypermetabolic cells have properties characteristic of the metabolism stimulation phase in cells showing a non-specific reaction to an injury 5. Hypermetabolism at the cellular level may be regarded as a stably prolonged phase of stimulated metabolism related to the cell non-specific reaction to an injury.
Factors Affecting Hypermetabolic State
Several factors can affect the hypermetabolic state, including:
- Disease processes that increase energy expenditure through direct or indirect processes 6
- Treatment, weight, choice of predictive formula, timing of the metabolic study, nutritional support, and level of consciousness 6
- Penetrating mechanism, burn mechanism, and maximum temperature, which are independent predictors of sustained hypermetabolism 7
Prevalence of Hypermetabolic State
Not all patients demonstrate the classic hypermetabolic response, and only a minority of injured patients are hypermetabolic in the first week after injury 7. Elevated temperature, penetrating mechanism, and burn mechanism are independently associated with sustained hypermetabolism.