Protein-Energy Malnutrition (PEM): Kwashiorkor and Marasmus

Protein-energy malnutrition (PEM) is the umbrella term for two major clinical syndromes of severe undernutrition in children - kwashiorkor and marasmus. Both are forms of Severe Acute Malnutrition (SAM), differing chiefly in whether protein deficiency or total caloric deficiency is predominant.

Overview

Feature	Marasmus	Kwashiorkor
Primary deficit	Both protein AND calories	Protein >> Calories
Weight	<60% of normal	60-80% of normal (masked by edema)
Edema	Absent	Present (hallmark)
Serum albumin	Normal or near-normal	Markedly low (hypoalbuminemia)
Subcutaneous fat	Severely depleted	Relatively spared
Muscle wasting	Severe	Mild-moderate
Liver	Normal	Enlarged, fatty
Skin/hair changes	Minimal	Characteristic (see below)
Appearance	"Old man" look - emaciated, head too large	Puffy, edematous

1. Marasmus

Definition & Cause

Marasmus develops when the diet is severely deficient in total calories (both protein and energy). A child is considered marasmic when weight falls to <60% of normal for sex, height, and age. - Robbins, Cotran & Kumar Pathologic Basis of Disease

Pathophysiology

The body mounts an adaptive response to near-total starvation:

Somatic protein compartment (skeletal muscle) is catabolized to supply amino acids for gluconeogenesis - essentially "eating itself" for energy
The visceral protein compartment (plasma proteins, organ proteins) is relatively spared - this is why serum albumin remains near-normal and edema does NOT develop
Subcutaneous fat is mobilized as fuel
Leptin production falls, stimulating the hypothalamic-pituitary-adrenal (HPA) axis to raise cortisol levels, which drives lipolysis

Clinical Features

Severe growth retardation
Extreme wasting of muscle and fat - limbs are emaciated, ribs visible
Head appears disproportionately large for the skeletal body
No edema (because albumin is preserved)
Anemia (multifactorial: iron, folate, protein deficiency)
Immune deficiency - especially T-cell-mediated immunity - making concurrent infections nearly universal, which imposes further catabolic stress

Childhood malnutrition: (A) Marasmus - note severe muscle and fat loss, head appears large. (B) Kwashiorkor - generalized edema with puffiness of face, hands, and legs.

Fig. from Robbins, Cotran & Kumar Pathologic Basis of Disease

2. Kwashiorkor

Definition & Etymology

Kwashiorkor occurs when protein deprivation is disproportionately greater than the caloric deficit. The word comes from the Ga language of Ghana and describes "the illness that comes to a child who is weaned when another baby is born" - reflecting the classic scenario of early weaning onto an almost exclusively carbohydrate diet. - Robbins, Cotran & Kumar Pathologic Basis of Disease

Epidemiology

Most common form of SAM in African children
Also high prevalence in Southeast Asia, Central America
Can occur worldwide in protein-losing states: nephrotic syndrome, protein-losing enteropathy, extensive burns, chronic diarrhea, fad diets (rare cases in the USA with rice-based milk substitutes)

Pathophysiology

Because caloric intake is less severely restricted, there is NO adaptive shift to muscle catabolism. Instead:

The visceral protein compartment is severely depleted - particularly albumin and carrier proteins
Hypoalbuminemia drops oncotic pressure → fluid leaks into interstitium → pitting edema (the hallmark)
Reduced synthesis of apolipoprotein components of VLDL → triglycerides accumulate in hepatocytes → fatty liver (hepatic steatosis)
Subcutaneous fat and muscle are relatively spared (but losses are masked by edema)
Oxidant stress plays a role: infection triggers a respiratory burst producing oxygen free radicals; superimposed on deficiency of antioxidants (zinc, copper, carotene, vitamins C and E), this oxidant load is thought to precipitate the full syndrome. - Harper's Illustrated Biochemistry, 32nd Ed

Clinical Features

Pitting edema - generalized or dependent; ascites, periorbital puffiness, pedal edema
Fatty hepatomegaly - due to impaired lipoprotein synthesis
Skin lesions - alternating zones of hyperpigmentation, desquamation, and hypopigmentation - classic "flaky paint" or "crazy paving" dermatosis
Hair changes - depigmentation, "flag sign" (alternating pale and dark bands), easy pluckability, straightening, fine texture
Moon face - due to edema
Apathy, listlessness, anorexia - these behavioral features distinguish kwashiorkor from marasmus
Weight 60-80% of normal (true tissue loss masked by fluid)
Immune deficiency and secondary infections (as in marasmus)

3. Pathological (Morphological) Changes

Liver

Kwashiorkor: enlarged and fatty (hepatic steatosis) due to reduced ApoB synthesis → impaired VLDL export → fat accumulates. Cirrhosis is rare.
Marasmus: liver is typically normal

Small Intestine

Kwashiorkor: decreased mitotic index in intestinal crypts → mucosal atrophy, villous blunting, loss of microvilli → disaccharidase deficiency (especially lactase) → secondary lactose intolerance. Clinically important: infants with kwashiorkor initially do NOT tolerate full-strength milk-based feeds. These changes are reversible with treatment.
Marasmus: minimal intestinal changes

Bone Marrow & Blood

Both: bone marrow hypoplasia (decreased red cell precursors)
Anemia is common and multifactorial - can be microcytic (iron deficiency), normocytic, or macrocytic (folate deficiency), or mixed
Robbins, Cotran & Kumar Pathologic Basis of Disease

Brain

In children born to malnourished mothers who also experience SAM in the first 1-2 years of life: cerebral atrophy, reduced neuron numbers, impaired myelination of white matter - with potential long-term neurodevelopmental consequences

Thymus and Lymphoid Tissue

Atrophy in both, but more marked in kwashiorkor - contributing to impaired immune function

4. Detection of PEM

Early detection relies on growth monitoring and anthropometry (Park's Textbook of Preventive and Social Medicine):

Weight-for-age: first indicator of PEM; maintained via growth charts
Mid-upper arm circumference (MUAC):
- 13.5 cm: satisfactory nutrition
- 12.5-13.5 cm: mild-moderate malnutrition
- <12.5 cm: severe malnutrition
- (Not reliable under 1 year of age; relatively stable between ages 1-5 years)
Serum albumin: low in kwashiorkor, near-normal in marasmus

5. Prevention

Adapted from FAO/WHO guidelines (Park's Textbook of Preventive and Social Medicine):

Health Promotion:

Promote exclusive breastfeeding and appropriate weaning foods
Develop low-cost, protein-and-energy-rich weaning formulas
Nutrition education; family planning (spacing births reduces early weaning)
Supplement pregnant and lactating women

Specific Protection:

Diet must include protein-rich foods (milk, eggs, legumes)
Immunization (reduces infections that precipitate/worsen PEM)
Food fortification programs

Early Diagnosis and Treatment:

Periodic nutritional surveillance
Growth chart monitoring at community level

Quick Memory Summary

Marasmus = Muscle wasting, Meager calories (total starvation), No edema, normal albumin - the child is a "little old man"

Kwashiorkor = Key feature is edema + Karbohydrate-only diet after weaning, fatty liver, flaky paint skin, apathy - the child looks "puffy but pale"

Sources:

Robbins, Cotran & Kumar Pathologic Basis of Disease (9780443264528), pp. 411-413
Robbins & Kumar Basic Pathology (9780323790185), pp. similar sections
Harper's Illustrated Biochemistry, 32nd Ed (9781260469943), p. 545
Park's Textbook of Preventive and Social Medicine (9789382219163), p. 737

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