Protein Energy Malnutrition

Protein Energy Malnutrition (PEM) is a spectrum of clinical conditions arising from a deficiency of energy, protein, or both, most commonly in under-five children. It ranges from mild growth faltering to the life-threatening extremes of marasmus, kwashiorkor, and marasmic-kwashiorkor. For NEET PG, the perennial favourites are the kwashiorkor–marasmus contrast, the WHO classification of Severe Acute Malnutrition (SAM), the 10-step WHO inpatient protocol, F-75/F-100 feeds, RUTF, and the older Gomez/Waterlow/Wellcome classifications.

Definition & terminology

• PEM / PCM (protein calorie malnutrition): an umbrella term for undernutrition due to inadequate intake or utilisation of protein and energy.
• Acute malnutrition (wasting): recent, rapid weight loss → low weight-for-height (W/H).
• Chronic malnutrition (stunting): long-standing → low height-for-age (H/A).
• Underweight: low weight-for-age (W/A) — a composite of both wasting and stunting; used by ICDS/Anganwadi growth charts in India.

High-yield: Wasting = acute (weight-for-height). Stunting = chronic (height-for-age). Underweight = weight-for-age (mixed). Remember: Weight-for-Height = Wasting — both have the acute "W".

Classifications (NEET PG goldmine)

Several classification systems coexist; examiners love mixing them up.

1. Gomez classification (weight-for-age, reference median)

Based on % of expected weight-for-age (50th centile of Boston/Harvard standard).

Grade	% of expected weight-for-age	Interpretation
Normal	> 90%	No malnutrition
Grade I (mild)	75–90%	Mild PEM
Grade II (moderate)	60–75%	Moderate PEM
Grade III (severe)	< 60%	Severe PEM

High-yield: Gomez uses weight-for-age, so it cannot distinguish wasting from stunting. Grade III (<60%) = severe.

2. IAP (Indian Academy of Paediatrics) classification

Also weight-for-age based (% of expected), widely used in Indian community practice.

Grade	% weight-for-age	Label
Normal	> 80%	—
Grade I	70–80%	Mild
Grade II	60–70%	Moderate
Grade III	50–60%	Severe
Grade IV	< 50%	Very severe

The suffix "K" is added to any grade if oedema (kwashiorkor) is present.

3. Waterlow classification (distinguishes wasting vs stunting)

Its strength is separating acute (wasting, low W/H) from chronic (stunting, low H/A).

	Stunting absent (normal H/A)	Stunting present (low H/A)
Wasting absent (normal W/H)	Normal	Nutritional dwarf (past/chronic)
Wasting present (low W/H)	Acute (wasted)	Acute on chronic

High-yield: Waterlow is the only classic system that separates acute (wasting) from chronic (stunting). Acute-on-chronic is the worst quadrant.

4. Wellcome Trust classification

Uses weight-for-age PLUS presence of oedema to name the syndrome — directly classifies into the three clinical types.

Weight (% of standard)	Oedema absent	Oedema present
60–80%	Underweight	Kwashiorkor
< 60%	Marasmus	Marasmic-kwashiorkor

High-yield: Wellcome is the classification that names kwashiorkor / marasmus / marasmic-kwashiorkor using weight + oedema. Oedema + weight 60–80% = kwashiorkor; <60% + oedema = marasmic-kwashiorkor.

5. WHO classification of SAM (current, operative one)

This is what governs management today.

Indicator	Cut-off for SAM
Weight-for-height (WHZ)	< −3 SD (z-score)
MUAC (mid-upper arm circumference, 6–59 mo)	< 11.5 cm
Bilateral pitting oedema	Present (any grade) → SAM
Visible severe wasting	Present

Moderate Acute Malnutrition (MAM): WHZ between −2 and −3 SD, or MUAC 11.5–12.5 cm, no oedema.

High-yield: SAM diagnostic triad — WHZ < −3 SD, MUAC < 11.5 cm, or bilateral pedal oedema. Any one suffices. MUAC < 11.5 cm is the single most field-friendly screening tool.

Aetiology & pathophysiology

Causes: inadequate intake (poverty, ignorance, early weaning failure, dilution of feeds), increased losses/demand (recurrent diarrhoea, measles, TB, HIV, malabsorption), and maternal/socioeconomic factors. The classic "malnutrition–infection vicious cycle": infection worsens nutrition; malnutrition impairs immunity → more infection.

Why kwashiorkor differs from marasmus

The historical explanation (protein deficiency with adequate calories → kwashiorkor; global energy + protein deficit → marasmus) is oversimplified. Modern understanding:

• Marasmus = adaptive response. Energy deficit → cortisol rises → muscle protein mobilised → albumin maintained → no oedema, gross wasting, "old man / monkey facies".
• Kwashiorkor = dysadaptation. Failure to adapt, with oxidative stress / free-radical injury, aflatoxin, leaky gut, dysbiosis implicated → hypoalbuminaemia, fatty liver, oedema. Albumin is low, but oedema is partly independent of albumin (capillary leak, sodium retention).

High-yield: Marasmus = "good adaptation, no oedema, albumin near-normal." Kwashiorkor = "failure of adaptation, oedema, hypoalbuminaemia, fatty liver." Total body sodium is HIGH in SAM despite low serum sodium.

Clinical features — Marasmus vs Kwashiorkor

Feature	Marasmus	Kwashiorkor
Core deficit	Energy (calorie)	Protein > energy (with stress)
Typical age	< 1 year	1–3 years (post-weaning)
Oedema	Absent	Present (pitting, dependent → generalised)
Weight loss	Severe	Masked by oedema
Subcutaneous fat	Grossly lost, buccal pad lost late	Preserved/variable
Muscle wasting	Marked	Present but hidden
Appetite	Often preserved/voracious	Poor / anorexia
Mental state	Alert, irritable, anxious	Apathetic, lethargic, miserable
Hair	Sparse, thin	Flag sign, depigmented, easily pluckable
Skin	Dry, wrinkled, "baggy pants" buttocks	Flaky-paint / crazy-pavement dermatosis
Liver	Not enlarged	Hepatomegaly (fatty liver)
Face	"Old man" / monkey facies	"Moon face", oedematous
Prognosis	Better	Worse (higher mortality)

High-yield eponyms: Flag sign = alternating bands of light/dark hair reflecting periods of poor/better nutrition (kwashiorkor). Flaky-paint dermatosis and crazy-pavement skin = kwashiorkor. Baggy-pants sign (loose skin folds over buttocks) = marasmus.

Mnemonic for kwashiorkor — "6 D's": Dermatosis, Depigmentation (hair/skin), Diarrhoea, Dependent oedema, Decreased growth, "Discontented" (apathy). Some add Distended abdomen and Diminished appetite.

Investigations / diagnosis

Diagnosis of SAM is clinical/anthropometric (WHZ, MUAC, oedema) — labs support management, not diagnosis.

• Anthropometry: weight, length/height, MUAC, oedema grading.
• Blood glucose — hypoglycaemia is a leading early killer.
• Electrolytes: Na⁺ (often low serum, high total body), K⁺ low, Mg²⁺ low, PO₄ low (critical for refeeding).
• Haemoglobin — anaemia (iron, folate, B12) common.
• Serum albumin / total protein — low in kwashiorkor (prognostic, not diagnostic).
• Screen for infection: sepsis, UTI, pneumonia, TB, HIV, malaria; signs of infection are often masked (no fever, no leucocytosis).

High-yield: In SAM, classic signs of infection (fever, tachycardia, leucocytosis) are blunted — treat all SAM children as if infected and give broad-spectrum antibiotics routinely on admission.

Management — WHO 10-step protocol for SAM

This is THE most repeated SAM topic. The 10 steps run across two phases.

Stabilisation (days 1–7) → Rehabilitation (weeks 2–6) → Follow-up.

Stepwise flow: 1 Hypoglycaemia → 2 Hypothermia → 3 Dehydration → 4 Electrolytes → 5 Infection → 6 Micronutrients → 7 Cautious initial feeding → 8 Catch-up growth → 9 Sensory stimulation → 10 Prepare for follow-up.

Step	Problem	Key action
1	Hypoglycaemia	10% glucose/sugar bolus; frequent 2-hourly feeds
2	Hypothermia (<35°C)	Keep warm, kangaroo care, treat hypoglycaemia/sepsis
3	Dehydration	ReSoMal orally/NGT, slowly; avoid IV unless shock
4	Electrolytes	Extra K⁺ + Mg²⁺; restrict Na⁺; ReSoMal is low-Na, high-K
5	Infection	Broad-spectrum antibiotics routinely (e.g. amoxicillin ± gentamicin); measles vaccine if due
6	Micronutrients	Vitamin A, folic acid, zinc, copper, multivitamins; NO iron in stabilisation
7	Cautious feeding	F-75 (75 kcal/100 mL), low protein/Na, frequent small volumes
8	Catch-up growth	Switch to F-100 / RUTF once appetite returns & oedema resolving
9	Sensory stimulation	Play, emotional support, maternal involvement
10	Follow-up	Discharge planning, prevent relapse

Mnemonic for order — "Sugar, Temperature, Dehydration, Electrolytes, Infection, Micronutrients, Feeding, Catch-up, Stimulation, Follow-up": the FIRST three (hypoglycaemia, hypothermia, dehydration) are the early killers.

High-yield: Iron is WITHHELD during the stabilisation phase — free iron promotes oxidative stress and bacterial growth (worsens infection/free-radical injury). Start iron only in the rehabilitation phase once the child is feeding well on F-100/RUTF.

High-yield: Use ReSoMal (Rehydration Solution for Malnutrition), NOT standard WHO-ORS, for dehydration in SAM — it has less sodium and more potassium plus added Mg, Zn, Cu. Exception: in cholera/profuse watery diarrhoea, standard ORS is used.

F-75 vs F-100 vs RUTF

Feed	Energy	Protein	When used	Notes
F-75	75 kcal/100 mL	~0.9 g/100 mL	Stabilisation	Low protein/Na, more carbohydrate; never for weight gain
F-100	100 kcal/100 mL	~2.9 g/100 mL	Rehabilitation	Higher protein/energy → catch-up growth
RUTF	~520–550 kcal/100 g	High	Rehab, especially community/OTP	Energy-dense lipid paste (peanut/milk), no water added → low infection risk, used in CMAM

High-yield: F-75 stabilises, F-100 builds. Premature high-protein/high-energy feeding causes refeeding syndrome and fluid overload. RUTF underpins community-based management (CMAM/OTP) for uncomplicated SAM with preserved appetite.

Criteria for inpatient vs community care

• Inpatient (facility): SAM with complications — failed appetite test, severe oedema (grade 3 / +++), hypoglycaemia, hypothermia, severe infection, severe anaemia, lethargy, or age < 6 months.
• Community/OTP (RUTF): uncomplicated SAM — passes appetite test, clinically well, alert.

Refeeding syndrome

A potentially fatal shift in fluids and electrolytes when starving patients are fed too aggressively. Insulin surge drives glucose, phosphate, potassium, and magnesium into cells.

• Hallmark: HYPOPHOSPHATAEMIA (most characteristic), plus hypokalaemia, hypomagnesaemia.
• Consequences: cardiac arrhythmia, heart failure, respiratory failure, rhabdomyolysis, seizures, thiamine deficiency (Wernicke's).
• Prevention: start low-energy (F-75), advance slowly, supplement K/Mg/PO₄, give thiamine before/with refeeding, monitor electrolytes.

High-yield: Refeeding syndrome = hypophosphataemia is the single most tested electrolyte. Give thiamine to prevent Wernicke encephalopathy when feeding restarts.

Complications

• Acute killers: hypoglycaemia, hypothermia, dehydration/shock, sepsis (often occult), heart failure (from over-rapid rehydration/feeding), severe anaemia.
• Micronutrient syndromes: Vitamin A deficiency → xerophthalmia / keratomalacia / corneal ulceration (give vitamin A on admission), zinc deficiency (acrodermatitis-like, poor healing), iodine and B-complex deficiencies.
• Electrolyte: hypokalaemia, hypomagnesaemia, hypophosphataemia (refeeding).
• Long-term: stunting, impaired cognition/IQ, recurrent infections, poor immunity (depressed cell-mediated immunity, thymic atrophy — "nutritional thymectomy").

High-yield: Vitamin A is given to ALL SAM children on admission (corneal protection); a child with malnutrition + eye signs (Bitot spots, corneal clouding) is a vitamin A emergency.

Key differentials

• Oedema in a child: nephrotic syndrome (proteinuria, no flaky-paint skin/hair changes, normal/raised appetite), congestive cardiac failure, protein-losing enteropathy, hepatic/renal failure, severe anaemia — distinguish from kwashiorkor by urinalysis, skin/hair signs, and dietary history.
• Wasting / failure to thrive: coeliac disease, cystic fibrosis, chronic infection (TB, HIV), inborn errors of metabolism, malignancy, malabsorption.
• Skin changes: acrodermatitis enteropathica (zinc), pellagra (niacin — dermatitis/diarrhoea/dementia), epidermolysis.

Recently asked / exam angle

• Which classification distinguishes acute from chronic malnutrition? → Waterlow (wasting vs stunting).
• Wellcome classification — naming kwashiorkor/marasmus by weight + oedema (oedema + 60–80% = kwashiorkor; <60% + oedema = marasmic-kwashiorkor).
• SAM cut-offs: MUAC < 11.5 cm; WHZ < −3 SD; bilateral pedal oedema — any single criterion.
• WHO 10 steps order, especially that iron is avoided in stabilisation and ReSoMal (not ORS) is used.
• F-75 vs F-100 energy content and phase of use.
• Refeeding syndrome → hypophosphataemia is the classic single-best-answer.
• First step / most immediate threat on admission: treat/prevent hypoglycaemia and hypothermia.
• Flag sign, flaky-paint dermatosis, baggy-pants sign image-based identification.
• Total body sodium is high despite low serum sodium → why Na is restricted.
• MUAC as the best community screening tool.

Rapid revision

1. Wasting = weight-for-height (acute); Stunting = height-for-age (chronic); Underweight = weight-for-age (mixed).
2. Gomez & IAP use weight-for-age; Waterlow separates wasting vs stunting; Wellcome names the syndrome using weight + oedema.
3. SAM = WHZ < −3 SD or MUAC < 11.5 cm or bilateral pitting oedema.
4. Marasmus: no oedema, albumin near-normal, "old-man facies", baggy-pants buttocks, good adaptation.
5. Kwashiorkor: oedema, hypoalbuminaemia, fatty liver, flaky-paint skin, flag-sign hair, apathy, poor appetite.
6. Kwashiorkor prognosis is worse than marasmus.
7. WHO 10 steps: Sugar → Temperature → Dehydration → Electrolytes → Infection → Micronutrients → Feeding → Catch-up → Stimulation → Follow-up.
8. Use ReSoMal (low Na, high K), NOT plain ORS — except in cholera.
9. No iron in the stabilisation phase (oxidative stress / infection); start in rehabilitation.
10. F-75 = stabilise (75 kcal/100 mL); F-100 = catch-up (100 kcal/100 mL); RUTF for community/OTP.
11. Refeeding syndrome → hypophosphataemia (+ hypokalaemia, hypomagnesaemia); give thiamine.
12. Give Vitamin A on admission to all; treat every SAM child as infected (signs are masked).