Reference — Fundamentals
Malnutrition & Refeeding Syndrome Reference
Malnutrition hides in plain sight on med-surg units and delays every kind of healing. And its treatment carries its own trap: feed a starved body too fast and the electrolytes crash. Screening, lab markers, and the refeeding playbook.
Educational use only. Nutrition repletion plans, electrolyte replacement, and refeeding rates are set by the provider and dietitian; lab reference ranges vary by laboratory. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Who to Screen Hard
- •Unintentional weight loss — >5% in a month or >10% in six months is significant
- •Poor intake for more than about 5 days, or NPO stretches stacking up in the hospital
- •Older adults — depression, dentition, dementia, isolation, fixed income
- •Chronic illness: cancer, COPD, heart failure, CKD, malabsorption (celiac, IBD)
- •Alcohol use disorder and substance use
- •Eating disorders — the highest-risk refeeding population
- •Dysphagia, post-stroke states, and anyone on prolonged clear-liquid diets
Assessment & Lab Markers
The best bedside markers are free: trended weight (the single most useful number), meal intake percentages, grip strength and visible muscle wasting (temples, clavicles, interossei), and a focused history of what eating actually looks like at home. Labs support — they do not replace — that picture:
| Lab | Typical Range | How to Read It |
|---|---|---|
| Albumin | ≈3.5–5.0 g/dL | Half-life ~20 days — reflects chronic status, but inflammation, liver disease, and fluid shifts lower it independent of nutrition. A blunt instrument. |
| Prealbumin (transthyretin) | ≈16–40 mg/dL | Half-life 2–3 days — responds quickly to nutrition changes, better for trending repletion, but also falls with inflammation. |
| Phosphorus | ≈2.5–4.5 mg/dL | THE refeeding lab — recheck after feeding starts; falling phosphorus in a refed patient is the syndrome's hallmark. |
| Potassium / Magnesium | K ≈3.5–5.0 mEq/L · Mg ≈1.5–2.5 mEq/L | Both shift into cells with refeeding; both cause arrhythmias when they fall. |
| Glucose | Per protocol | Hyperglycemia is common as carbohydrate delivery resumes; insulin drives the electrolyte shifts further. |
Refeeding Syndrome — The Mechanism
In starvation, cells run on fat and intracellular stores quietly empty. Reintroduce carbohydrate and insulin surges, driving phosphorus, potassium, and magnesium into cells — serum levels plummet within days. Hypophosphatemia is the hallmark. The result: muscle weakness (including respiratory failure), arrhythmias, heart failure, seizures, and death — caused by feeding, not by the starvation itself.
The Refeeding Playbook
Identify the at-risk patient before the first calorie
Little or no intake for days, significant weight loss, eating disorders, alcohol use disorder, chronic malnutrition — flag them to the team before feeding starts, whatever the route (PO, enteral, or TPN).
Check and correct electrolytes first
Baseline phosphorus, potassium, magnesium — replacement often begins before or alongside the first feeds per orders.
Start low, go slow
Calories begin well below goal and advance over days per the dietitian/provider plan. Aggressive day-one feeding is the mistake the syndrome punishes.
Give thiamine before glucose in alcohol use disorder
Carbohydrate without thiamine can precipitate Wernicke encephalopathy — thiamine comes first.
Monitor daily while advancing
Electrolytes (especially phosphorus), glucose, fluid balance, daily weight, cardiac rhythm in severe cases — for roughly the first week of refeeding.
NCLEX Pearls
- ✦Refeeding syndrome = hypophosphatemia first; watch potassium and magnesium with it.
- ✦Highest-risk refeeders: eating disorders, alcohol use disorder, prolonged NPO/starvation.
- ✦Start low and go slow applies to PO, enteral, and parenteral routes alike.
- ✦Thiamine before glucose in the alcohol-use patient.
- ✦Prealbumin trends recent nutrition (half-life 2–3 days); albumin reflects weeks and is confounded by inflammation.
- ✦Unintentional weight loss >5% in a month or >10% in six months is significant — trended weight beats any single lab.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with American Nurses Association (ANA) Standards of Practice · The Joint Commission. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →