Vitamin A
Xerophthalmia Vernacular Terms
Matang Manok
Mata Ajam
Khwak Moan
Gred Gradei
Mager Aagh
Korapothu
Chicken Eyes
Chicken Eyes
Dusk Blindness
Scaly as Fish
Fish Scales
Scaly
Tagalog
Indonesian
Khmer
Thai
Bengali
Singhalese
Impact of VADD on Public Health
• 250 million preschool-age children
have subclinical vitamin A deficient
•7.2 million pregnant women
• 3 million have clinical xerophthalmia
• 300, 000 are blind from xerophthalmia
Impact of Vitamin A Intervention on
Child Survival
“Improvement of vitamin A status in young
child populations… leads to a reduction in
all-cause mortality rates of about 23%.”
United Nations, 1993
“Improved vitamin A nutriture would be expected to
prevent approximately 1.3-2.5 million deaths
annually among children aged under 5 years.”
Bulletin of WHO, 1992
BUT Mechanisms involved are poorly understood
Functions
• Vision (night, day, colour)
• Epithelial cell integrity against infections
• Immune response
• Haemopoiesis
• Skeletal growth
• Fertility (male and female)
• Embryogenesis
Tests of Vitamin A Status
Subclinical
• Relative dose-response test
• Serum retinol
Decreased
Status
• Retinal rod function
• Conjunctival impression
cytology (CIC)
Clinical
• Night blindness
• Conjunctival and corneal eye
signs
Factors that may Affect Plasma
Vitamin A or Retinol Levels
• Liver disease deacreases plasma retinal levels, probably
as a result of a combination of decreased synthesis and
secretion of RBP.
• Stress decreases plasma retinol levels.
• Protein-energy malnutrition decreases RBP production
because of a limited supply of protein substrate.
Consequently hepatic release of vitamin A is impaired
resulting in decreased serum retinol levels.
• Zinc deficiency decreases plasma retinol levels via its role
in the synthesis of RBP.
• Infections and parasitic infections lower plasma retinol
levels.
• Cystic fibrosis is associated with a defect in the transport
of vitamin A from the hepatic stores to the periphery resulting
in decreased levels of circulating retinol and RBP.
• Low fat diets impair absorption of vitamin A, lowering
plasma retinol concentrations.
• Estrogens, either endogenous or those used in
contraceptive agents, increase plasma retinol and RBP
apparently as a result of incresed mobilization of Vitamin A
from the liver.
• Age, sex and race influence serum retinol levels, as
indicated by the NHANES II survey results.
For the test, a baseline blood sample is taken immediately
before the administration of a small oral dose (450µg) of
vitamin A (as retinyl acetate or retinol palmitate); followed
by a second blood sample, five hours later. The RDR (%) is
calculated as:
Plasma retinol at 5 hr – Plasma retinol at 0hr
X 100
RDR(%) =
Plasma retinol at 5 hr
Vitamin-A-replete subjects have RDR values ranging from
0% to 14%. Relative dose response values greater than 14%
to 20% are indicative of marginal vitamin A status in
humans, the cutoff value depending on the coefficient of
variation for the analytical method used to measure serum
Percentage of Children with Positive
RDR Test Classified by Serum Retinol
Levels
Serum Retinol (µg/dL)
%
Number Tested
<20
100
12
21 - 29
86
21
30 - 40
26
19
>40
3
39
Total tested
91
Treatment Schedule (orally)
Immediately on diagnosis:
<6 months
50, 000 IU
6 months-12 months
100, 000 IU
> 12 months
200, 000 IU
Next day
Same age-specific dose
At least two weeks later
Same age-specific dose
Xerophthalmia Classification
XN
Night Blindness
X1A
Conjunctival Xerosis
X1B
Bitot’s Spot with Conjunctival Xerosis
X2
Corneal Xerosis
X3A
Corneal Xerosis with ulceration
X3B
Keratomalcia
XF
Xerophthalmic Fundus
XS
Corneal scars from Xerophthalmia
WHO criteria of a public health
problem of xerophthalmia
• Night Blindness
(XN)
In > 1%
• Bitots spot
(X1B)
In > 0.5%
• Corneal
Xerosis/Ulceration/
Keratomalacia
(X2, X3A, X3B)
In >0.01%
• Corneal scar
(XS)
In > 0.05%
• Plasma retinol of
<0.35µmol/l (10 µg/dl)
In > 5%
Percent with Serum Vitamin A:
n
<10 µg/dL 10-19 µg/dL >20 µg/dL
252
8
37
55
Children with nightblindness or Bitot’s 325
spots
30
55
15
Children with
corneal
xerophthalmia
75
24
1
Normal Children
98
Serum vitamin A levels in a sample of Indonesian children with
and without ocular lesions. Conversion factor SI units(µmol/L)=
x 0.035