Chapter 14: Nutrition

Nutrition overview examines the critical role of nutrition within clinical biochemistry and metabolic medicine, detailing how metabolic processes adapt to various physiological stressors. The text establishes the foundational requirements for energy and protein intake, highlighting the body's shift from glycogen utilization to gluconeogenesis and ketone body oxidation during prolonged starvation. It contrasts these adaptive mechanisms with the hypermetabolic responses triggered by trauma and sepsis, specifically the "ebb" and "flow" phases that necessitate increased nitrogen and caloric support for wound healing. Clinicians are guided through various nutritional assessment strategies, including the use of the MUST screening tool, anthropometric markers like skin-fold thickness, and biochemical indicators such as transferrin and transthyretin, while acknowledging the diagnostic limitations of serum albumin. The chapter provides a deep dive into medical interventions for undernutrition, comparing the physiological benefits of enteral feeding with the complex management of parenteral nutrition, which requires careful monitoring for line infections and metabolic imbalances. A significant focus is placed on the pathophysiology of refeeding syndrome, characterized by potentially lethal electrolyte shifts like hypophosphataemia, and the hormonal regulation of obesity involving leptin, adiponectin, and neuropeptide Y. By integrating clinical signs with laboratory data, this study guide offers an essential framework for managing malnutrition, anorexia nervosa, and the global health challenge of obesity.