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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.

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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

  • Retinal rod function

  • Conjunctival impression cytology (CIC)

Decreased Status

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

26

19

30 - 40

>40

3

39

91

Total tested


Treatment Schedule (orally) Serum Retinol Levels

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 Serum Retinol Levels

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 Serum Retinol Levels

  • Night Blindness

(XN)

In > 1%

  • Bitots spot

(X1B)

In > 0.5%

  • Corneal Xerosis/Ulceration/Keratomalacia

In >0.01%

(X2, X3A, X3B)

  • Corneal scar

(XS)

In > 0.05%

  • Plasma retinol of <0.35µmol/l (10 µg/dl)

In > 5%


Percent with Serum Vitamin A: Serum Retinol Levels

n

<10 µg/dL

>20 µg/dL

10-19 µg/dL

252

8

37

55

Normal Children

Children with night-blindness or Bitot’s spots

325

30

55

15

Children with corneal xerophthalmia

75

98

24

1

Serum vitamin A levels in a sample of Indonesian children with and without ocular lesions. Conversion factor SI units(µmol/L)= x 0.035


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