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Explain PEM with kwashiorkor and marasmus

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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

FeatureMarasmusKwashiorkor
Primary deficitBoth protein AND caloriesProtein >> Calories
Weight<60% of normal60-80% of normal (masked by edema)
EdemaAbsentPresent (hallmark)
Serum albuminNormal or near-normalMarkedly low (hypoalbuminemia)
Subcutaneous fatSeverely depletedRelatively spared
Muscle wastingSevereMild-moderate
LiverNormalEnlarged, fatty
Skin/hair changesMinimalCharacteristic (see below)
Appearance"Old man" look - emaciated, head too largePuffy, 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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