11. Refeeding syndrome

Question 1

metabolic adaptations to starvation

Answer 1

• glucose levels ↓ and insulin levels ↓
• Glucagon levels ↑
• glycogenolysis in the liver and lipolysis of triacetylglycerol in fat reserves producing fatty acids and glycerol
• These are used by tissues for energy and converted to ketone bodies in the liver
• As glycogen reserves become depleted, gluconeogenesis is stimulated in the liver, utilising amino acids lactate and glycerol resulting in the synthesis of glucose for use by the brain
• Body reduces all energy consuming metabolic pathways including action of cellular pumps, allowing electrolytes to leak across cell membranes and be excreted
• Sodium and fluid leak into cells, resulting in an increase in intracellular sodium and water
• Cardiac, intestinal and renal functions become impaired , leading to reduced ability to excrete excess sodium and water

Question 2

METABOLIC CHANGES TO REINTRODUCTION OF NUTRITION

Answer 2

• ↑ Insulin production
• ↓ Glucagon secretion
• ↑ Cellular uptake of glucose, phosphate, potassium (
simultaneous fall in serum levels)
• Reactivation of Na+/K+ membrane pump leads to ↑potassium into cells and ↑sodium and fluid loss out of cells into extracellular space.
• Na+/K+ pump utilises magnesium as a co-factor ↓ its
availability
• ↓ renal function ↓ ability to excrete sodium and fluid resulting in fluid overload
• Phosphate used for energy storage in the form of adenosine triphosphate (ATP)
• ↑demand for thiamine as part of carbohydrate metabolism
• ↑glucose levels may occur as a consequence of excessive glucose introduction to a starved system adapted to fat metabolism
• Simulation of protein synthesis leads to increased anabolic tissue growth which in turn leads to increased cellular demand for phosphate, potassium, glucose and water

Question 3

What is the main outcome of starvation and of refeeding?

Answer 3

→The main outcome in starvation is that body switches the main energy source from carbohydrate to protein and fat, electrolytes are depleted and water and sodium are retained
→ The main outcome of the re-introduction of nutrition in those with refeeding syndrome is a return to carbohydrate metabolism and increased uptake of electrolytes intracellularly resulting in low serum levels

Question 4

What are the manifestations of refeeding?

Answer 4

• Disturbances of body fluid distribution
• Hypophosphatemia
• Hypokalaemia
• Hypomagnesaemia
• Thiamine deficiency
• Altered glucose metabolism

Question 5

What things would be considered to see if a patient is at risk of refeeding syndrome>?

Answer 5

• Dietary intake (very little or no food intake for > 5 days)
• BMI ( < 18.5kg/m2)
• % weight loss ( unintentional) in last 3-6 months
• Electrolyte levels e.g. potassium, phosphate, magnesium (if low)
• Alcohol abuse, use of insulin, chemotherapy, antacids or diuretics
• Malabsorption e.g. chronic vomiting, diarrhoea

Question 6

What 3 biochemical markers must be monitored in refeeding syndrome?

Answer 6

• Potassium- K+
• Phosphate- Po43-
• Magnesium- Mg2+

Question 7

What else need to be considered alongside feeding?

Answer 7

• Immediately before and during feeding provide full dose of IV vitamin B preparation daily
• Balanced multivitamin/ trace element supplement daily
• Provide electrolyte replacement as per NICE/ PENG or local guidelines
• Monitoring of cardiac rhythm
• Restore circulatory volume e.g. meet fluid requirements from day one (consider which type of fluid replacement appropriate consider sodium and
carbohydrate provision and monitor for fluid overload)
• Monitor fluid balance- fluid chart