VITAMIN A DEFICIENCY

Definition

1 IU of Vitamin A = 0.3 mcg of Retinol 1 Retinol Equivalent (RE) = 3.333 IU of Vitamin A

Sources of Vitamin A

Note: The liver stores Vitamin A (as retinol palmitate) for 6-9 months. Carotene conversion to Vitamin A is impaired in malnourished children and those with diarrhoea.

Functions of Vitamin A

1. Vision - Essential for production of retinal pigments needed for dim-light (scotopic) vision
2. Epithelial integrity - Maintains normal functioning of glandular and epithelial tissue lining intestinal, respiratory, and urinary tracts
3. Growth - Supports skeletal growth
4. Anti-infective - Deficiency causes increased susceptibility to infection and lowered immune response
5. Anti-cancer - May protect against epithelial cancers (e.g., bronchial carcinoma)

Clinical Features of Vitamin A Deficiency

WHO Classification of Xerophthalmia

┌─────────────────────────────────────────────────────────────┐
│              XEROPHTHALMIA (WHO Classification)              │
├──────────────┬──────────────────────────────────────────────┤
│   STAGE      │   SIGN                                        │
├──────────────┼──────────────────────────────────────────────┤
│   XN         │   Night Blindness                            │
│   X1A        │   Conjunctival Xerosis                       │
│   X1B        │   Bitot's Spots                              │
│   X2         │   Corneal Xerosis                            │
│   X3A        │   Corneal Ulceration / Keratomalacia (< 1/3) │
│   X3B        │   Keratomalacia (≥ 1/3 corneal area)         │
│   XS         │   Corneal Scar                               │
│   XF         │   Xerophthalmic Fundus                       │
└──────────────┴──────────────────────────────────────────────┘

FLOWCHART: Progression of Vitamin A Deficiency

         VITAMIN A DEFICIENCY
                  │
                  ▼
       ┌─── Night Blindness (XN) ────────────────────────────┐
       │    (earliest symptom - impaired dark adaptation)     │
       └─────────────────────────────────────────────────────┘
                  │
                  ▼
       ┌─── Conjunctival Xerosis (X1A) ──────────────────────┐
       │    Dry, non-wettable, muddy, wrinkled conjunctiva    │
       │    ("like sand banks at receding tide")              │
       └─────────────────────────────────────────────────────┘
                  │
                  ▼
       ┌─── Bitot's Spots (X1B) ─────────────────────────────┐
       │    Triangular, pearly-white/yellowish foamy spots    │
       │    on bulbar conjunctiva; frequently bilateral       │
       └─────────────────────────────────────────────────────┘
                  │
                  ▼
       ┌─── Corneal Xerosis (X2) ────────────────────────────┐
       │    Dull, dry, non-wettable, opaque cornea            │
       │    May progress to corneal ulceration                │
       └─────────────────────────────────────────────────────┘
                  │
                  ▼
       ┌─── Keratomalacia (X3B) ─────────────────────────────┐
       │    ⚠ GRAVE MEDICAL EMERGENCY                        │
       │    Liquefaction/softening of cornea                  │
       │    Cornea may burst → Permanent Blindness            │
       └─────────────────────────────────────────────────────┘

Extra-Ocular Manifestations

• Follicular hyperkeratosis (skin changes)
• Anorexia and growth retardation
• Increased morbidity and mortality from respiratory and diarrhoeal diseases (even in mild VAD)

Assessment of Vitamin A Deficiency (WHO Prevalence Criteria)

Presence of any one criterion is evidence of a xerophthalmia problem in the community.

Vitamin A Deficiency in India

• 5.7% of children in India suffer from eye signs of VAD
• Bitot's spots prevalence exceeds WHO cut-off of 0.8-1.0% in many states
• Only 21% of children aged 12-35 months receive a Vitamin A dose
• States with better coverage: Tamil Nadu (37.2%), Goa (37.3%), Kerala (38.2%), West Bengal (41.2%)
• National Programme for prevention of nutritional blindness was initiated in 1970; modified in 1992; integrated into RCH/NRHM under Tenth Five Year Plan

Treatment

Treat URGENTLY - nearly all early stages are reversible

All children with corneal ulcers should receive Vitamin A regardless of whether deficiency is suspected.

Prevention and Control

FLOWCHART: Prevention Strategy (Triad)

            PREVENTION OF VITAMIN A DEFICIENCY
                         │
         ┌───────────────┼───────────────┐
         ▼               ▼               ▼
   SHORT-TERM      MEDIUM-TERM      LONG-TERM
   MEASURES         MEASURES         MEASURES
         │               │               │
   Massive dose    Food              Dietary
   Vitamin A      fortification      diversification,
   supplementation (Vanaspati,       Nutrition
                   Margarine,        education,
                   Milk)             Breastfeeding,
                                     Infection control,
                                     Immunization
                                     (esp. Measles)

Vitamin A Prophylaxis Programme (National Programme)

Since Vitamin A can be stored in the body for 6-9 months, a massive dose every 6 months effectively "immunizes" the child against xerophthalmia.

• Children with measles - one dose of Vitamin A (if not received in previous 1 month)
• Children with severe malnutrition - one additional dose of Vitamin A
• Children with xerophthalmia - treated at health facilities

Toxicity (Hypervitaminosis A)

High carotene intake causes harmless carotenaemia (yellowing of skin/plasma). Teratogenic effects of massive doses are a concern.

• Write the WHO classification table neatly - examiners love it
• Use the word "Xerophthalmia" correctly and define it
• Always mention Keratomalacia as a medical emergency
• State the National Programme doses precisely (100,000 IU at 9 months; 200,000 IU every 6 months up to 5 years)
• Mention India-specific data (5.7% prevalence, 1970 programme) - shows command of community medicine
• The WHO prevalence criteria table shows you know the public health aspect which HODs specifically look for