Table 15 Diagnostic criteria for RFS in critically ill patients (Refs. [4, 67, 507,508,509,510,511,512])

Ref. [67, 507, 508]

Serum phosphorus concentration of any of the following within 72 h of initiating nutrition therapy

•  ≤ 2.0 mg/dL

• Decrease of 0.5 mg/dL or more from the previously measured value

ESPEN refeeding hypophosphatemia [4]

Serum phosphorus concentration after nutritional administration falls into one of the following categories

•  ≤ 2.0 mg/dL

• Decrease of more than 0.5 mg/dL

Evidence-based and consensus-supported algorithm [510]

• If the serum phosphorus concentration decreases by 30% or more from the baseline or falls to ≤ 1.8 mg/dL within 72 h of initiating nutrition therapy

• Or, if any two of 1) to 3) apply

1) Serum phosphorus concentration ≤ 2.4 mg/dL

2) Serum magnesium concentration ≤ 1.8 mg/dL

3) Serum potassium concentration ≤ 3.4 mEq/L

Diagnosis

• If electrolyte abnormalities are the only symptoms, then it is regarded as imminent RFS

• If clinical symptoms appear in addition to electrolyte abnormalities, it is regarded as manifest RFS

ASPEN Consensus Recommendation for Refeeding Syndrome [509]

1) Serum phosphorus, potassium, and/or magnesium concentrations decrease by 10% or more

2) This decrease occurs within 5 days of the resumption of nutrition or an increase in administered energy

Additionally, the severity classification is as follows when the above criteria apply:

Mild

10–20% decrease

Moderate

20–30% decrease

Severe

• A decrease of 30% or more

• And/or organ dysfunction resulting from a decrease in any of these electrolytes

• And/or due to vitamin B₁ (thiamin) deficiency