FORM & FUNCTION (Starvation 3) Flashcards
Refeeding syndrome:
-driven by electrolyte imbalance
-caused from the reintroduction of food after long periods of malnutrition
*starvation can deplete electrolytes important for metabolic functions
Serum electrolyte tests:
-do not always show abnormality since many key ions are stored intracellularly (within cells)
>K+
>Mg2+
>phosphates
Electrolyte imbalance:
-major complication in refeeding after starvation
*electrolytes as cofactors
>movement into intracellular is insulin driven
Refeeding after starvation steps:
-increase glucose
-increase in insulin
-glycogen, fat and protein synthesis
-SURGE in intracellular electrolyte requirement
>depletes extracellular K, Mg, and P
Normal phosphate level:
-2.5mg/dL
Hypophosphatemia:
-low, phosphate in blood (less than 2.5mg/dL)
-hallmark of refeeding syndrome
-affects all organs
Phosphate:
-key molecules in creating ATP
Consequences of low phosphate:
-inadequate ATP formation
-muscle weakness
-myocardial insufficiency
-respiratory insufficiency
*RBCs are directly affected first (2,3-BPG and glycolysis)
2,3-BPG:
-need it to release oxygen from hemoglobin
-when low phosphate, then it is low
Low 2,3-BPG:
-increase hemoglobin affinity for O2 (left shift)
>harder to release O2
-reduced oxygen release at tissues
RBC glycolysis:
-rely on it to generate ATP (can’t do aerobic respiration as they have no mitochondria)
RBC glycolysis: low phosphate availability:
-low ATP production
-accumulation of glyceraldehyde-3-P (low phosphate available to regenerate ATP
-overcommitment to preparatory phase->rapid ATP depletion->increased hemolysis
Low phosphate in RBC leads to:
-decreased ATP: hemolysis risk
-decreased 2,3-BPG: hypoxia risk
*both contribute to impaired aerobic metabolism
Hemolysis risk:
-rupture of RBC
>reduced RBC count
Hypoxia risk:
-tissue oxygen deprivation
>O2 tightly bout to RBC
