RDN-AP cheat sheet

Indirect calorimetry (IC) is the reference method for resting metabolic rate; use it when predictive equations are unreliable (obesity, critical illness, amputation, burns). Measured RQ 0.85–1.0 suggests mixed substrate oxidation; RQ >1.0 suggests net lipogenesis or overfeeding.

Predictive equations (Mifflin-St Jeor, Penn State, Ireton-Jones) are estimates: Mifflin-St Jeor for healthy adults, Penn State 2010 for ventilated obese patients, Ireton-Jones for burn/trauma. Apply stress and activity factors cautiously; systematic overfeeding is common.

Nitrogen balance = nitrogen intake − (urinary urea nitrogen + 4 g insensible/other losses). A positive balance of +2 to +4 g/day supports anabolism; interpret with caution in renal failure, diuresis, and steroid use.

Sarcopenia (EWGSOP2): low muscle strength is primary; low muscle quantity/quality and low physical performance confirm severity. Screen with SARC-F; use grip strength and DXA or BIA for confirmation.

BIA estimates body composition from bioelectrical impedance; results are affected by hydration status, edema, and electrolyte shifts, limiting accuracy in critically ill or edematous patients.

Malnutrition diagnosis (GLIM): at least one phenotypic criterion (weight loss, low BMI, reduced muscle mass) plus at least one etiologic criterion (reduced intake/assimilation, inflammation/disease burden).

Resting energy expenditure in critical illness: measured REE often 1.0–1.3× predicted; avoid cumulative overfeeding (>~25 kcal/kg/day in most) which increases hyperglycemia, CO2 production, and hepatic steatosis.

Enteral nutrition within 24–48 h is preferred in hemodynamically stable critically ill adults; early EN preserves gut integrity and reduces infectious complications. Hold EN during active shock with escalating vasopressors until resuscitation is complete.

Refeeding syndrome risk: BMI <16, unintentional weight loss >15% in 3–6 months, little or no intake >10 days, low baseline K/Mg/phos. Start 10–20 kcal/kg and advance slowly; replete thiamine before feeding and monitor electrolytes daily.

Permissive underfeeding (target ~70–80% of measured or calculated needs) is acceptable in the first week of critical illness; trophic feeding is an option in ARDS and acute lung injury.

Propofol delivers 1.1 kcal/mL (10% lipid emulsion); account for it in energy totals and avoid excessive lipid load when combined with EN/PN lipids.

Continuous renal replacement therapy removes amino acids and water-soluble vitamins; protein needs may reach 1.5–2.5 g/kg/day in CRRT, adjusted for urea kinetics and acid-base status.

In acute pancreatitis, start oral or enteral feeding as soon as tolerated; nasogastric feeding is acceptable if oral intake fails. Parenteral nutrition is reserved for intolerance to EN.

Sepsis and multiorgan failure: prioritize early EN, avoid overfeeding, monitor glucose 140–180 mg/dL, and reassess protein delivery with nitrogen balance and clinical status.

Gastric residual volume monitoring: do not routinely hold EN for GRV <500 mL in the absence of other signs of intolerance; prokinetics (metoclopramide, erythromycin) may improve gastric emptying.

Standard EN formulas provide 1.0–1.2 kcal/mL; concentrated (1.5–2.0 kcal/mL) formulas are used for fluid restriction. Fiber-containing formulas may help with diarrhea but are avoided in ileus or bowel obstruction.

PN indications: EN contraindicated (bowel obstruction, high-output fistula, severe malabsorption, ischemic bowel) or EN unable to meet >60% of needs after 7–10 days.

PN complications: catheter-related bloodstream infection, hyperglycemia, refeeding syndrome, hepatic steatosis, gallbladder sludge, and electrolyte disturbances. Use a standardized, multidisciplinary PN order set.

Peripheral PN is limited by osmolarity (>900 mOsm/L causes phlebitis); use central access for high-osmolarity or long-term PN.

EN complications: aspiration, diarrhea, tube dislodgement, and metabolic derangements. Elevate head of bed 30–45°, verify tube placement, and use closed-system formulas to reduce contamination.

Transition from PN to EN: wean PN only when EN provides >60% of energy needs; abrupt discontinuation risks hypoglycemia, especially with high insulin states.

Type 2 diabetes: medical nutrition therapy with individualized carbohydrate distribution, adequate fiber (14 g/1000 kcal), and weight management. Glycemic targets are individualized; A1c <7% is common but higher targets apply to older or frail patients.

Chronic kidney disease: protein intake 0.6–0.8 g/kg/day for non-dialysis CKD with adequate energy (30–35 kcal/kg); dialysis patients need 1.0–1.2 g/kg/day. Monitor potassium, phosphorus, and sodium individually.

Heart failure: sodium restriction is individualized (commonly 2–3 g/day); avoid excessive fluid restriction unless hyponatremia. Monitor weight daily and watch for cardiac cachexia.

Hypertension: DASH-style eating pattern, sodium <2300 mg/day (ideal <1500 mg), potassium-rich foods unless CKD or on potassium-sparing drugs.

COPD: energy needs may be 1.2–1.5× predicted due to increased work of breathing; small frequent meals and a lower-carbohydrate, higher-fat pattern can reduce CO2 production in hypercapnic patients.

Multimorbidity requires prioritizing the diet that supports the dominant condition and quality of life; a single restrictive diet rarely fits all conditions. Screen for polypharmacy and drug-nutrient interactions.

Preterm infants: trophic feeds (10–20 mL/kg/day) can begin within 24–48 h; advance 15–30 mL/kg/day as tolerated. Human milk is preferred; fortify with human milk fortifier to meet protein and mineral needs.

Very low birth weight (<1500 g) infants need 3.5–4.5 g/kg/day protein and 110–135 kcal/kg/day; monitor growth with Fenton or WHO charts appropriate for gestational age.

Necrotizing enterocolitis (NEC): hold enteral feeds, provide parenteral nutrition, and reintroduce feeds slowly after resolution. Human milk reduces NEC risk.

Pediatric malnutrition assessment uses WHO or CDC growth standards, mid-upper arm circumference, and weight-for-length or BMI-for-age z-scores.

Cystic fibrosis: energy needs 110–200% of estimated requirements; pancreatic enzyme replacement with meals and fat-soluble vitamin supplementation are standard.

Pediatric obesity: family-based, multicomponent behavioral interventions; avoid very-low-calorie diets in children except under specialist supervision. Screen for comorbidities (dyslipidemia, insulin resistance, hypertension).

Short bowel syndrome: after resection, adapt with enteral feeding; use parenteral nutrition if EN cannot meet needs. Monitor for D-lactic acidosis, B12 deficiency, and fat-soluble vitamin deficiencies.

Cirrhosis: 1.2–1.5 g/kg/day protein is recommended; do not restrict protein unless hepatic encephalopathy is refractory. Late-evening snack reduces catabolism.

Acute liver failure: avoid protein restriction; provide adequate energy and protein, monitor glucose closely (hypoglycemia common), and watch for cerebral edema.

Chronic kidney disease: individualized protein restriction, sodium restriction, and monitoring of potassium and phosphorus. Plant-based proteins may reduce phosphorus load.

Nephrotic syndrome: manage protein intake moderately, control sodium, and address dyslipidemia; avoid excessive protein which may worsen proteinuria.

Gastroesophageal reflux and gastroparesis: smaller, more frequent meals, avoid high-fat meals in gastroparesis, and consider prokinetics.

Pancreatic insufficiency: pancreatic enzyme replacement (lipase units with meals), fat-soluble vitamin supplementation, and monitoring of fat malabsorption.

Cancer cachexia: multimodal approach with nutrition counseling, exercise, and pharmacologic agents (e.g., megestrol acetate) for appetite; protein intake 1.2–1.5 g/kg/day when feasible.

ERAS (Enhanced Recovery After Surgery): preoperative carbohydrate loading, avoidance of prolonged fasting, early oral intake, and early mobilization reduce complications and length of stay.

Preoperative nutrition: for severe malnutrition, 7–14 days of preoperative nutrition support (oral or enteral) before major surgery can reduce complications.

Transplant: pre-transplant nutrition optimization; post-transplant immunosuppressants (tacrolimus, cyclosporine, steroids) interact with grapefruit, potassium, and sodium. Monitor for weight gain, diabetes, and dyslipidemia.

Hematopoietic stem cell transplant: high risk of mucositis, infection, and graft-versus-host disease; nutrition support often required. Avoid raw foods and unpasteurized products during neutropenia.

Surgical patients: early enteral feeding after major abdominal surgery is safe and preferred; PN is reserved for prolonged ileus or complications.

Oncology patients receiving radiation to the head and neck: monitor for mucositis, dysphagia, and weight loss; consider prophylactic feeding tube placement in high-risk patients.

Levels of evidence: systematic reviews/meta-analyses of RCTs are highest; then RCTs, cohort studies, case-control studies, case series, and expert opinion. GRADE rates certainty and strength of recommendations.

PICO framework: Population, Intervention, Comparison, Outcome-used to formulate answerable clinical questions.

Internal validity threats: selection bias, confounding, attrition, and measurement bias. Randomization and blinding reduce these.

Quality improvement: use PDSA (Plan-Do-Study-Act) cycles, run charts, and control charts to track process and outcome measures over time.

Statistical significance vs clinical significance: p-values indicate probability, not effect size. Report confidence intervals and minimally important differences.

Nutrition screening tools: MUST, NRS-2002, and MNA have different settings and validity; choose the tool validated for the population and setting.

Audit and feedback, care bundles, and standardized order sets are evidence-based strategies to improve nutrition care processes.

Ethical principles: autonomy, beneficence, nonmaleficence, and justice guide decisions about artificial nutrition and hydration, especially in terminal illness.

Advance care planning: document patient preferences for artificial nutrition and hydration; respect informed refusal.

Interprofessional collaboration: dietitians, physicians, nurses, pharmacists, speech-language pathologists, and social workers coordinate care; clear role delineation improves outcomes.

Scope of practice: RDN scope is defined by state licensure, credentialing, and institutional policy; know when to refer to specialists.

Medicare and insurance coverage for medical nutrition therapy: covered for diabetes and renal disease with a physician referral; document medical necessity.

Conflict of interest: disclose financial relationships and avoid industry influence on clinical recommendations.

Cultural humility and health literacy: tailor education to the patient's language, literacy, and cultural food practices to improve adherence.

Anthropometry: weight, height, BMI, waist circumference, and skinfold thickness; interpret trends rather than single values.

Biochemical markers: albumin and prealbumin are acute-phase reactants and poor markers of nutritional status in inflammation.

Clinical assessment: physical signs of deficiency (e.g., glossitis, edema, muscle wasting) plus medical and dietary history.

Dietary assessment methods: 24-hour recall, food frequency questionnaire, food records, and diet history; each has strengths and limitations.

Energy needs: indirect calorimetry is preferred; predictive equations are alternatives with known error.

Protein needs: 1.2–2.0 g/kg/day in critical illness, higher in burns and CRRT.

Micronutrient assessment: monitor vitamins and minerals in malabsorption, bariatric surgery, and prolonged PN.

Acute respiratory distress syndrome: avoid overfeeding; consider trophic feeds and monitor for hypercapnia.

Burns: hypermetabolism; energy needs may be 1.5–2.0× predicted; high protein (1.5–2.0 g/kg/day) and early EN.

Trauma: early EN within 24–48 h; monitor for ileus and abdominal compartment syndrome.

Acute kidney injury: protein needs 1.2–2.0 g/kg/day; avoid unnecessary protein restriction.

Hepatic failure: do not restrict protein; provide adequate energy and monitor glucose.

Obesity in critical illness: use measured or adjusted body weight; high-protein, hypocaloric feeding may be appropriate.

Monitoring: daily electrolytes, glucose, triglycerides, and fluid balance; reassess nutrition status weekly.

Enteral access: nasogastric, nasojejunal, gastrostomy, and jejunostomy; choose based on duration and anatomy.

Formula selection: polymeric for normal gut function, elemental/semi-elemental for malabsorption, disease-specific for organ failure.

PN components: dextrose, amino acids, lipids, electrolytes, vitamins, trace elements, and insulin as needed.

PN monitoring: glucose, electrolytes, liver enzymes, triglycerides, and fluid status.

Complications of EN: aspiration, diarrhea, constipation, tube occlusion, and metabolic abnormalities.

Complications of PN: infection, thrombosis, hyperglycemia, refeeding syndrome, and hepatobiliary disease.

Weaning: transition to oral diet when intake is adequate; monitor for refeeding and hypoglycemia.

Diabetes: carbohydrate counting, glycemic index, and physical activity; individualized goals.

CKD: protein restriction, sodium restriction, potassium and phosphorus management; dialysis patients need higher protein.

Heart failure: sodium restriction, fluid management, and monitoring for cachexia.

COPD: energy needs increased; small frequent meals; monitor for hypercapnia.

Hypertension: DASH pattern, sodium restriction, and potassium-rich foods.

Multimorbidity: prioritize the dominant condition and quality of life; avoid overly restrictive diets.

Polypharmacy: screen for drug-nutrient interactions (e.g., warfarin and vitamin K, MAOIs and tyramine).

Preterm infants: human milk, fortification, and monitoring of growth and electrolytes.

VLBW: high protein and energy needs; monitor for NEC and feeding intolerance.

NEC: hold feeds, PN, and slow reintroduction.

Pediatric malnutrition: WHO/CDC growth charts, MUAC, and z-scores.

Cystic fibrosis: enzyme replacement, fat-soluble vitamins, and high-energy diet.

Pediatric obesity: family-based behavioral interventions; avoid very-low-calorie diets.

Pediatric PN: monitor for cholestasis, electrolyte disturbances, and growth.

Short bowel syndrome: enteral adaptation, PN if needed, monitor for deficiencies.

Cirrhosis: 1.2–1.5 g/kg/day protein; late-evening snack; avoid protein restriction.

Acute liver failure: no protein restriction; monitor glucose and cerebral edema.

CKD: individualized protein, sodium, potassium, and phosphorus restriction.

Nephrotic syndrome: moderate protein, sodium control, and lipid management.

Gastroparesis: small frequent meals, low-fat, and prokinetics.

Pancreatic insufficiency: enzyme replacement and fat-soluble vitamins.

Cancer cachexia: multimodal approach, protein 1.2–1.5 g/kg/day, appetite stimulants.

ERAS: carbohydrate loading, no prolonged fasting, early oral intake.

Preoperative nutrition: 7–14 days for severe malnutrition.

Transplant: immunosuppressant interactions, monitor weight and metabolic complications.

HSCT: mucositis, infection risk, nutrition support; avoid raw foods.

Surgical patients: early EN after major surgery; PN for prolonged ileus.

Head and neck radiation: monitor mucositis and weight loss; feeding tube if needed.

Levels of evidence: systematic reviews > RCTs > cohort > case-control > case series > expert opinion.

PICO: Population, Intervention, Comparison, Outcome.

Internal validity: randomization, blinding, and control of confounders.

QI: PDSA cycles, run charts, and control charts.

Statistical vs clinical significance: p-values vs effect size and confidence intervals.

Screening tools: MUST, NRS-2002, MNA; choose validated tool.

Audit and feedback and care bundles improve nutrition care.

Ethical principles: autonomy, beneficence, nonmaleficence, justice.

Advance care planning: document preferences for artificial nutrition and hydration.

Interprofessional collaboration: dietitians, physicians, nurses, pharmacists, SLPs, social workers.

Scope of practice: state licensure, credentialing, institutional policy.

Medicare coverage: MNT for diabetes and renal disease with physician referral.

Conflict of interest: disclose financial relationships.

Cultural humility and health literacy: tailor education to patient needs.