What are the signs of Protein-Energy Malnutrition (PEM) in adults?

Signs of Protein-Energy Malnutrition (PEM) in Adults

Protein-energy malnutrition in adults presents with involuntary weight loss exceeding 5% over 6 months, visible muscle wasting with prominent skeletal structures, reduced muscle strength, and low serum albumin, though albumin primarily reflects inflammation rather than pure nutritional status. 1

Anthropometric and Physical Signs

Body Composition Changes

• Involuntary weight loss >5% over 6 months or >10% beyond 6 months indicates serious malnutrition requiring immediate evaluation 1
• BMI <20 kg/m² (or <18.5 kg/m² for severe undernutrition) serves as a key screening threshold 1, 2
• Visible skeletal structures including prominent ribs, spine, and hip bones due to loss of both muscle and adipose tissue 1
• Reduced mid-arm muscle circumference with mid-upper arm muscle area <32 cm² in men or <18 cm² in women 1, 2
• Decreased triceps skinfold thickness reflecting depleted fat stores 2

Muscle Wasting

• Severe muscle depletion with visible loss of muscle mass in temporal areas, shoulders, and extremities 1, 2
• Reduced handgrip strength indicating functional muscle impairment 3
• Impaired gait speed and difficulty with chair stand tests reflecting functional decline 1

Clinical and Functional Signs

Appetite and Intake

• Anorexia (loss of appetite) with markedly reduced food intake 1, 4
• Reduced food intake below 50% of requirements for >3 days or estimated energy intake <60% of requirement for 1-2 weeks 1
• Severe fatigue and reduced physical activity capacity limiting daily function 1

Functional Impairment

• Loss of ability to live independently as functionality declines 1
• Inability to perform normal activities due to reduced muscle strength 1
• Impaired physical performance status across multiple domains 1

Skin and Tissue Changes

• Abnormal skin turgor where pinched skin over shoulder blades remains tented or slowly returns to position, indicating dehydration 1
• Pale mucous membranes around eyes, mouth, tongue, and interdigital spaces suggesting anemia 1
• Sunken eyes in severe cases of dehydration and starvation 1
• Increased vulnerability to pressure ulcers and infections due to compromised tissue integrity 1

Laboratory Findings

Protein Markers

• Low serum albumin (<38 g/L or <3.5 g/dL), though this reflects both nutritional status and inflammatory response 3, 5, 1, 2
• Low prealbumin (transthyretin) which is more sensitive than albumin for tracking nutritional status 5, 6
• Low transferrin indicating depleted visceral protein stores 5
• Simultaneous reduction of total protein, albumin, and globulin in severe cases 5

Metabolic Derangements

• Water and electrolyte imbalances including hyponatremia and hypokalemia 7
• Hypolipidemia and hypolipoproteinemia reflecting overall metabolic dysfunction 7
• Deficiency of antioxidant vitamins and enzymes 7
• Depression of cell-mediated immune function 7

Critical Diagnostic Pitfalls

Do not rely solely on serum albumin as a nutritional marker, as it primarily reflects inflammatory response rather than nutritional depletion—when albumin is low with elevated C-reactive protein, this indicates inflammation-driven malnutrition rather than pure starvation 3, 1. The combination of low albumin with elevated CRP suggests that inflammation may be a more powerful predictor of poor outcome than malnutrition alone 3.

Do not rely solely on weight or BMI in acute settings, as fluid administration and rapid tissue wasting can mask true nutritional status 1. In patients with kidney disease, BMI use in overhydrated patients may lead to underestimating malnutrition 3.

Recognize that cooperation is required for handgrip strength testing, and there is no absolute consensus on measurement protocols or standard reference values 3.

Classification by Severity

GLIM Criteria Framework

The Global Leadership Initiative on Malnutrition (GLIM) criteria require at least one phenotypic criterion (non-volitional weight loss, low BMI, or reduced muscle mass) AND one etiological criterion (reduced food intake/assimilation or disease burden/inflammation) for diagnosis 3. However, these criteria have not been validated in all hospitalized adult populations 3.

Types of PEM

• Mixed type (35% of hospitalized GI patients): depletion of fat, muscle protein, and visceral protein 2
• Kwashiorkor-like (24% of hospitalized GI patients): characterized by edema as the central feature, with visceral protein depletion predominating 2, 8
• Marasmus-like: primarily energy deficiency with severe wasting but preserved visceral proteins 8

Protein-Energy Wasting in Kidney Disease

In patients with chronic kidney disease, the term "protein-energy wasting" describes decreased body stores of protein and energy fuel (lean body mass and fat stores) associated with diminished functional capacity 3. This condition is highly prevalent, affecting 11-54% of non-dialysis CKD patients and 28-54% of hemodialysis patients 3, 4.

Prognostic Significance

Serum albumin <3.5 g/dL is associated with increased morbidity and mortality across multiple clinical settings 5, and the presence of PEM is strongly associated with higher rates of morbidity and mortality in dialysis patients 3, 4. Panhypoproteinemia (low total protein, albumin, and globulin) indicates more severe disease than isolated hypoalbuminemia 5.