What are the signs of vitamin A deficiency?

Signs of Vitamin A Deficiency

Vitamin A deficiency presents with a characteristic progression of ocular manifestations, beginning with night blindness as the earliest symptom, followed by xerophthalmia, Bitot spots, and potentially progressing to keratomalacia and permanent blindness if untreated. 1, 2

Ocular Signs (Most Characteristic)

Early Manifestations

• Night blindness (nyctalopia) is the earliest and most sensitive clinical indicator, resulting from insufficient rhodopsin synthesis in the retina 1, 3
• Xerophthalmia (dry eyes) develops as deficiency progresses, caused by loss of mucus-secreting goblet cells and reduced tear production 1, 3

Progressive Ocular Changes

• Bitot spots appear as gray/white, foamy lesions on the conjunctiva, representing keratinized epithelium 1, 2, 3
• Conjunctival dryness with loss of normal luster 1
• Corneal xerosis (corneal dryness and keratinization) represents advancing disease 3
• Corneal ulceration can develop as deficiency worsens 3

Severe/Late Manifestations

• Keratomalacia (corneal softening and melting) can occur even without bacterial infection or inflammatory infiltration 3
• Corneal scarring leads to permanent vision loss 4
• Permanent blindness results from corneal maceration and secondary infection if left untreated 4, 3

Non-Ocular Signs

Dermatologic Manifestations

• Dry hair has been documented in vitamin A deficiency 3
• Follicular hyperkeratosis may be present 5

Growth and Development

• Growth cessation occurs in children with deficiency 5
• Impaired bone development 5

Immune System Effects

• Increased susceptibility to infections, particularly respiratory and gastrointestinal infections 6, 7
• Impaired immune function increases risk of secondary infections that can worsen eye damage 1, 3

Rare Clinical Presentations

In specific populations (particularly cystic fibrosis patients), extremely rare manifestations have been reported including:

• Benign intracranial hypertension (pseudotumor cerebri) 4
• Uni- or bilateral facial palsy in infants 4

Clinical Context and Pitfalls

A critical pitfall is that clinical signs of overt deficiency are extremely rare in developed countries despite biochemical deficiency being present. 4 The goal of evaluation should be to correct suboptimal levels before clinical manifestations appear, rather than waiting for overt signs 4.

Serum retinol levels should not be assessed during acute infection or inflammation, as retinol concentrations fall in response to inflammation independent of true vitamin A status, potentially masking deficiency 4, 2, 3.

The progression from night blindness to xerophthalmia to keratomalacia represents increasing severity and tissue depletion of vitamin A stores 1, 2. Early recognition and treatment at the night blindness stage can prevent irreversible corneal damage and blindness 1.