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Malnutrition and Nutritional Assessment¶

Chapter 345 | Part 10: Disorders of the Gastrointestinal System · Part 10 – Gastrointestinal Disorders · Chapter 345

Key Clinical Points¶

Malnutrition affects 30–50% of hospitalized patients and is associated with poor wound healing, compromised immune status, impaired organ function, increased length of stay, readmissions, higher mortality, and increased healthcare costs.
The GLIM consensus criteria require at least one etiologic criterion (inflammation/disease burden/reduced intake) AND one phenotypic criterion (weight loss, low BMI, or reduced muscle mass) for diagnosis.
Albumin and prealbumin are negative acute-phase reactants and are unreliable indicators of nutritional status in the presence of inflammation; C-reactive protein (CRP) is a positive acute-phase reactant useful for identifying inflammation.
BMI <18.5 kg/m² indicates underweight but does not rule out malnutrition in overweight patients (e.g., sarcopenic obesity).
Calf circumference is a practical and valid clinical estimate of skeletal muscle mass, requiring less training than mid-upper arm circumference, with established cutoff values for various BMI ranges.
Inflammation elevates resting energy expenditure and promotes anabolic resistance and catabolism in muscle; severe inflammation may render nutritional interventions supportive rather than therapeutic.
Copper deficiency is rare but seen in premature infants, malabsorption, nephrotic syndrome, and Wilson's disease treated with chronic high-dose zinc; diagnosis involves low serum copper (<65 μg/dL) and low ceruloplasmin (<20 mg/dL).
Selenium deficiency causes Keshan disease (endemic cardiomyopathy) in regions with low soil selenium; chronic ingestion of large amounts leads to selenosis (hair/nail brittleness, garlic breath, rash, myopathy).
Chromium potentiates insulin action, though its usefulness in treating type 2 diabetes is uncertain; rich sources include yeast, meat, and grain products.
The Nutrition Care Process involves a 4-step cycle: Screening → Assessment → Plan Development → Monitoring.

DEFINITION & OVERVIEW¶

• Definition: Malnutrition is a condition characterized by inadequate intake, absorption, or utilization of nutrients, leading to adverse health outcomes. • Prevalence: Occurs in 30–50% of hospitalized patients depending on the setting, diagnosis, and criteria used. • Consequences: Associated with poor wound healing, compromised immune status, impaired organ function, increased length of stay, readmissions, higher mortality, and increased healthcare costs.

1.1 Nutritional Assessment Process¶

The Nutrition Care Process in the hospital setting involves: 1. Screening: Identifying patients at risk of malnutrition (typically by bedside nurse or clinical dietitian using validated tools). 2. Comprehensive Assessment: For patients at risk, including review of medical/surgical/social history, dietary intake and weight history, medication profile, laboratory tests, body composition, and nutrition-focused physical examination. 3. Plan Development: Clinical dietitian designs an individualized intervention and monitoring plan. 4. Monitoring: Tracking response to therapy and making adjustments to the plan.

1.2 Inflammation and Malnutrition¶

• Impact of Inflammation: Presence of inflammation can render historic parameters (albumin, prealbumin) unreliable. • Clinical Approach: In patients with high levels of inflammation, nutrition care is supportive; at moderate or low levels, it may be therapeutic in reducing nutritional deficits and improving outcomes.

EPIDEMIOLOGY¶

• Risk Factors: ◦ Acute or chronic inflammation. ◦ The inflammatory milieu, especially when severe, modifies nutrient requirements by elevating resting energy expenditure and promoting anabolic resistance and catabolism in muscle. ◦ Clinical Contexts: ◦ Severe acute inflammatory response: Critical illness, major infection, burns, trauma, or closed head injury. ◦ Mild-to-moderate chronic inflammatory response: Chronic cardiometabolic, oncologic, or gastrointestinal disease; organ failure.

ETIOLOGY & PATHOPHYSIOLOGY¶

• Drivers of Malnutrition: ◦ Reduced food intake. ◦ Disease burden. ◦ Inflammation (promotes anorexia and decreases food intake). • Impact of Inflammation: ◦ Increases resting energy expenditure. ◦ Promotes anabolic resistance and catabolism in muscle. ◦ Clinical Implications: Severe inflammation may reduce the benefit of nutritional interventions to being supportive rather than therapeutic; associated malnutrition may diminish the effectiveness of medical therapies.

DIAGNOSTIC APPROACH¶

Screening: Identify patients at risk using validated tools (e.g., Nutritional Risk Screen).
Comprehensive Assessment: Includes medical/surgical/social history, dietary intake and weight history, medication profile, laboratory tests, body composition, and nutrition-focused physical examination.
Diagnosis & Grading (GLIM Criteria): Requires at least one etiologic criterion (inflammation/disease burden/reduced intake) AND one phenotypic criterion (weight loss, low BMI, or reduced muscle mass).
Severity Determination:

Table 345-1: Thresholds for Severity Grading of Malnutrition • Stage 1 (Moderate): Requires 1 phenotypic criterion meeting these grades: ◦ Weight Loss: 5–10% within the past 6 months, or 10–20% beyond 6 months. ◦ Low BMI: <20 if <70 years; <22 if ≥70 years. ◦ Reduced Muscle: Mild-to-moderate deficit (per validated assessment methods). • Stage 2 (Severe): Requires 1 phenotypic criterion meeting these grades: ◦ Weight Loss: >10% within the past 6 months, or >20% beyond 6 months. ◦ Low BMI: <18.5 if <70 years; <20 if ≥70 years.

Table 345-2: Common Body Composition Studies, Laboratories, and Other Studies Used in Nutrition Assessment • Recommended Methods: ◦ Air plethysmography: Measures body volume to compute fat mass and fat-free mass (limited availability/validation in diverse populations). ◦ Calf circumference: Practical and valid clinical estimate of skeletal muscle mass; requires less training than mid-upper arm circumference. ◦ Imaging (CT or MRI): Used to quantify fat and fat-free mass when scans are taken for other diagnostic purposes. ◦ Ultrasound: Promising, portable method using high-frequency sound waves to capture live images of muscle tissues. ◦ C-reactive protein (CRP): Used to confirm systemic inflammation; lacks specificity as a biomarker for malnutrition but complements assessment. Elevated levels may indicate reduced food intake and lack of response to intervention. ◦ Nitrogen balance (NB): Reflects degree of catabolism and adequacy of protein replacement in patients with normal renal/liver function. Requires 24-h urine collection. Formula: Nitrogen balance = (protein delivery [g]/6.25) − (urinary urea nitrogen + 4 insensible losses). • Not Recommended Methods: ◦ BUN, serum creatinine: Influenced by factors unrelated to malnutrition (e.g., renal/hepatic insufficiency). ◦ Creatinine height index (CHI): Influenced by renal function, meat consumption, physical activity, and trauma. ◦ Electrocardiogram: Not a specific indicator of malnutrition. ◦ Serum proteins (albumin, prealbumin, transferrin, and retinol-binding protein): Not recommended as indicators due to influence by systemic inflammation, hepatic/renal insufficiency, protein-losing enteropathies, corticosteroids, hydration, and iron status.

MANAGEMENT & TREATMENT¶

Screening: Identify patients at risk of malnutrition.
Assessment: Perform comprehensive assessment for patients identified as high-risk.
Plan Development: Clinical dietitian designs an individualized intervention and monitoring plan.
Monitoring: Track response to therapy → adjust plan as needed.

KEY PEARLS & HIGH-YIELD POINTS¶

• Inflammation vs. Lab Values: ◦ Albumin and prealbumin are negative acute-phase reactants → unreliable in inflammation. ◦ CRP is a positive acute-phase reactant → useful for identifying inflammation. • Muscle Mass Assessment: ◦ Calf circumference is preferred over mid-upper arm circumference due to ease of use. • Specific Nutrient Deficiencies: ◦ Copper: Seen in premature infants, malabsorption, nephrotic syndrome, and Wilson's disease (high-dose zinc). Diagnosis: serum <65 μg/dL; ceruloplasmin <20 mg/dL. ◦ Selenium: Causes Keshan disease (endemic cardiomyopathy); excess causes selenosis (hair/nail brittleness, garlic breath, rash, myopathy). ◦ Chromium: Potentiates insulin action; useful for some conditions but utility in type 2 diabetes is uncertain. Sources: yeast, meat, and grain.

Reference Tables¶

TABLE 345-1 Thresholds for Severity Grading of Malnutrition Into Stage 1 (Moderate) and Stage 2 (Severe) Malnutrition…¶

Harrison's 22e, p.2616

	PHENOTYPIC CRITERIAa
	WEIGHT LOSS (%)	LOW BODY MASS INDEX (kg/m2)b	REDUCED MUSCLE MASSc
Stage 1/moderate malnutrition (requires 1 phenotypic criterion that meets this grade)	5%–10% within the past 6 months, or 10%–20% beyond 6 months	<20 if <70 years, <22 if ≥70 years	Mild-to-moderate deficit (per validated assessment methods; see below)
	>10% within the past 6 months, or >20% beyond 6 months	<18.5 if <70 years, <20 if ≥70 years

TABLE 345-2 Common Body Composition Studies, Laboratories, and Other Studies Used in Nutrition Assessment TEST Body…¶

Harrison's 22e, p.2618

TEST	NOTES
Body Composition Studies (Recommended)
Air plethysmography	May be used to assess body composition. It comprises a dual-chamber, sealed compartment containing an oscillating diaphragm, which allows it to measure body volume using Poisson’s law, and compute fat mass and fat-free mass. However, its validity in a racially diverse population needs further studies, and it is not readily available in most hospitals.
Calf circumference	A practical and valid clinical estimate of skeletal muscle mass, in which low calf circumference indicates muscle loss. Ethnic specific reference ranges are available, and measurements should be adjusted in persons with body mass index different from the normal range (underweight, overweight, or obese). The technique requires less training than mid-upper arm circumference.
Imaging with computed tomography (CT) or magnetic resonance imaging (MRI)	May be used to quantify fat and fat-free mass when scans are taken for other diagnostic purposes. Both are costly, and CT entails x-ray exposure.
Ultrasound	A promising method to assess body composition as the equipment is easily portable. It uses high-frequency sound waves to capture live images of muscle tissues. Since most studies examined a single muscle, it is unclear if results can be extrapolated to reflect overall nutritional status. More research is needed to establish standardization of measurement protocol.
Laboratory Tests and Other Studies (Recommended)
C-reactive protein (CRP)	May be used to confirm systemic inflammation. While inflammation may be associated with malnutrition, CRP lacks specificity as a biomarker for diagnosing malnutrition. Nevertheless, when combined with other nutrition assessment methods, CRP can complement the diagnostic process for malnutrition. In addition, elevated levels may be associated with reduced food intake and a lack of response to nutritional interventions.
Nitrogen balance (NB)	May be used to reflect the degree of catabolism and adequacy of protein replacement delivery in patients with normal renal and liver function. Method requires collection of 24-h urine. Nitrogen balance = (protein delivery [g]/6.25) − (urinary urea nitrogen + 4 insensible losses).
Laboratory Tests and Other Studies (Not Recommended)
Blood urea nitrogen (BUN), serum creatinine	Not recommended as malnutrition indicators. Although low BUN and serum creatinine may reflect reduced muscle mass, their levels are influenced by factors unrelated to malnutrition (e.g., renal and hepatic insufficiency).
Creatinine height index (CHI)	Not recommended as a malnutrition indicator. CHI = (24-h urinary creatinine excretion/ideal urinary creatinine for gender and height) × 100. Although urinary creatinine excretion reflects muscle mass, it can be influenced by renal insufficiency, meat consumption, physical activity, and trauma. Requires accurate 24-h urine collection.
Electrocardiogram	Not recommended as a malnutrition indicator. Although prolonged QT interval may be present in severely malnourished patients, the former can be influenced by factors unrelated to malnutrition.
Serum proteins (albumin, prealbumin, transferrin, and retinol-binding protein)	Not recommended as a malnutrition indicator. Their levels are influenced by factors other than malnutrition (e.g., systemic inflammation, hepatic and renal insufficiency, protein-losing enteropathies, corticosteroids, hydration, and iron status), reducing their specificity in diagnosing malnutrition and evaluating nutritional interventions. However, they remain valuable for predicting clinical outcomes.
Total lymphocyte count	Not recommended as malnutrition indicator. Low levels are influenced by factors unrelated to malnutrition.