Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st year (First Year) Biochemistry ppt lectures Topic 87 Vitamin A Deficiency Notes. - biochemistry notes pdf, biochemistry mbbs 1st year notes pdf, biochemistry mbbs notes pdf, biochemistry lecture notes, paramedical biochemistry notes, medical biochemistry pdf, biochemistry lecture notes 2022 ppt, biochemistry pdf.
VITAMIN A DEFICIENCY
VITAMIN A DEFICIENCY
? Vitamin A deficiency is a lack of vitamin A in humans. It is
common in developing countries but rarely seen in
developed countries
? Night blindness is one of the first signs of vitamin A
deficiency .
? Night blindness is the difficulty for the eyes to adjust to dim
light. Affected individuals are unable to distinguish images in
low levels of illumination. People with night blindness have
poor vision in the darkness, but see normally when adequate
light is present.
Xerophthalmia Vernacular Terms
Matang Manok
Chicken Eyes Tagalog
Mata Ajam
Chicken Eyes
Indonesian
Khwak Moan Dusk Blindness Khmer
Gred Gradei Scaly as Fish
Thai
Mager Aagh Fish Scales Bengali
Korapothu
Scaly
Singhalese
VITAMIN A DEFICIENCY
? Ocular manifestation: Xerophthalmia
The eye fails to produce tears that leads to conjunctival dryness and
damage
"Dry eye".
Blindness may result since plays role in phototransduction
? Phototransduction
Is a process by which light is converted into electrical signals in the cells
of the retina of the
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
BITOTS SPOTS
CORNEAL OPACITIES
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
VITAMIN A DEFICIENCY
? Vitamin A deficiency also diminishes the ability to fight
infections. In countries where children are not immunized ,
infectious disease like measles have higher fatality rates.
? Even mild, subclinical deficiency can also be a problem, as it
may
? Increase children's risk of developing respiratory and diarrheal
infections
? Decrease growth rate
? Slow bone development
? Decrease probability of survival from serious il ness.
CAUSES OF VITAMIN A
DEFICIENCY
? The major cause is diets which include few animal sources of pre-
formed vitamin A .
? Breast milk of a lactating mother with vitamin A deficiency contains
little vitamin A ,which provides a breast-fed child with too little
vitamin A.
CAUSES OF VITAMIN A
DEFICIENCY
? In addition to dietary problems, there are other
causes of vitamin A deficiency
? Iron deficiency can affect vitamin A uptake.
? Excess alcohol consumption can deplete vitamin A
? A stressed liver may be more susceptible to vitamin A
toxicity.
HYPERVITAMINOSIS A
? Hypervitaminosis A refers to the effects of excessive vitamin
A (specifically retinoid) intake
? Hypervitaminosis A occurs when the maximum limit for liver
stores of retinoids is exceeded.
? The excess vitamin A enters the circulation causing systemic
toxicity.
? Betacarotene (is an organic compound which is a strongly-
coloured red-orange pigment abundant in plants and fruits. -
Carotene is also the substance in carrots that colours them
orange) a precursor of vitamin A, is selectively converted into
retinoids, so it does not cause toxicity.
HYPERVITAMINOSIS A
? Signs of acute toxicity include
? Nausea
? Vomiting
? Headache
? Dizziness
? Blurred vision
? Loss of muscular coordination
Hypervitaminosis A
Other effects
? Birth defects
? Liver problems
? Skin discoloration
? Hair loss
? Excessive skin dryness
? Angular cheilitis is an inflammatory lesion at the labial corner
of the mouth, and often occurs bilateral y. The condition manifests
as deep cracks or splits. In severe cases, the splits can bleed when
the mouth is opened and shal ow ulcers or a crust may form.
This post was last modified on 05 April 2022