Chi-Square Test Non Parametric Test Categorical Variable
Vitamin C deficiency
1. By- Professor (Dr.) Namrata Chhabra
Biochemistry For Medics - Lecture Notes
www.namrata.co
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Biochemistry For Medics
2. Vitamin C (ascorbic acid) plays a role in
collagen, carnitine, hormone, and amino acid
formation.
It is essential for wound healing and
facilitates recovery from burns.
Vitamin C is also an antioxidant, supports
immune function, and facilitates the
absorption of iron.
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3. Scurvy is caused by a dietary deficiency of
vitamin C.
The body's pool of vitamin C can be depleted
in 1-3 months.
Risk factors include the following:
Babies who are fed only cow's milk during the first
year of life are at risk.
Alcoholism
Elderly individuals who eat a tea-and-toast diet
Retired people who live alone and those who eat
primarily fast food
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4. Economically disadvantaged persons tend to not
purchase foods high in vitamin C (eg, green
vegetables, citrus fruits), which results in them being
at high risk.
Vitamin C deficiency has been noted in refugees who
are dependent on external suppliers for their food and
have limited access to fresh fruits and vegetables.
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5. Cigarette smokers require increased intake of
vitamin C because of lower vitamin C absorption and
increased catabolism.
Pregnant and lactating women and those with
thyrotoxicosis require increased intake of vitamin C
because of increased utilization.
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6. People with anorexia nervosa or anorexia from
other diseases such as AIDS or cancer are at
increased risk of vitamin C deficiency.
People with type 1 diabetes have increased vitamin
C requirements, as do those on hemodialysis and
peritoneal dialysis.
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7. Because vitamin C is absorbed in the small
intestine, people with disease of the small intestine
such as Crohn’s, Whipple, and celiac disease are at
risk.
Iron overload disorders may lead to renal vitamin C
wasting.
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9. Vitamin C is functionally most relevant for the
triple-helix formation of collagen; a vitamin C
deficiency results in impaired collagen
synthesis.
Proline and lysine hydroxylases are required
for the post synthetic modification of
procollagen to collagen.
Vitamin C is necessary as a coenzyme for
these hydroxylases.
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11. Formation of intercellular cement substances
in connective tissues, bones, and dentin is
defective, resulting in weakened capillaries
with subsequent hemorrhage and defects in
bone and related structures.
Hemorrhaging is a hallmark feature of scurvy
and can occur in any organ.
Hair follicles are one of the common sites of
cutaneous bleeding
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12. Bone tissue formation becomes impaired,
which, in children, causes bone lesions and
poor bone growth.
Fibrous tissue forms between the diaphysis
and the epiphysis, and costochondral
junctions enlarge.
Densely calcified fragments of cartilage are
embedded in the fibrous tissue.
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13. Subperiosteal
hemorrhages,
sometimes
due to small
fractures, may
occur in
children or
adults.
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14. Early symptoms are malaise
and lethargy.
After 1-3 months, patients
develop shortness of breath
and bone pain.
Myalgias may occur because of
reduced carnitine production.
Other symptoms include skin
changes with roughness, easy
bruising and petechiae, gum
disease, loosening of teeth,
poor wound healing, and
emotional changes.
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15. Dry mouth and dry eyes
In the late stages, jaundice, generalized
edema, oliguria, neuropathy, fever, and
convulsions can be seen.
Vital signs: Hypotension may be observed
late in the disease. This may be due to an
inability of the resistance vessels to constrict
in response to adrenergic stimuli.
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16. Skin: Perifollicular
hemorrhages (See
figure),purpura, and
ecchymoses are seen most
commonly on the legs and
buttocks where hydrostatic
pressure is the greatest.
Poor wound healing and
breakdown of old scars may be
seen.
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18. Head and neck:
Gum swelling, friability, bleeding, and
infection with loose teeth;
mucosal petechiae;
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19. Scleral icterus (late, probably secondary to
hemolysis); and pale conjunctiva are seen.
Conjunctival hemorrhage,
Bleeding into the periorbital area, eyelids, and
retrobulbar space also can be seen.
Alopecia may occur secondary to reduced
disulfide bonding.
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21. Chest and
cardiovascular:
Scorbutic rosary (ie,
sternum sinks inward)
may occur in children.
High-output heart failure
due to anemia can be
observed.
Bleeding into the
myocardium and
pericardial space has
been reported.
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22. Extremities:
Fractures, dislocations, and tenderness of
bones are common in children.
Bleeding into muscles and joints may be
seen.
Edema may occur late in the disease.
Gastrointestinal: Loss of weight secondary
to anorexia is common.
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23. Diagnosis is usually made clinically in a patient
who has skin or gingival signs and is at risk of
vitamin C deficiency are normal
Laboratory Investigations
A plasma or leukocyte vitamin C level can confirm
clinical diagnosis.
Scurvy occurs at levels generally less than 0.1 mg/dL.
Symptoms occur at levels below 2.5 mg/L, which is
considered deficiency.
Levels of 2.5-5 mg/L indicate depletion.
Levels can be low in patients who have tuberculosis,
rheumatic fever, or other chronic illnesses; those who
smoke cigarettes; and patients on oral contraceptive
drugs.
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24. Capillary fragility can be checked by inflating a
blood pressure cuff and looking for petechiae on
the forearm.
Bleeding time, clotting time and Prothrombin are
estimated to rule out other bleeding disorders
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25. An Fe deficiency anemia is generally
observed.
Vitamin C enhances the absorption of iron
from the small intestine.
This may contribute to the anemia seen with
vitamin C deficiency.
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26. Loss of trabeculae results
in a ground-glass
appearance.
The cortex thins.
A line of calcified,
irregular cartilage (white
line of Fraenkel) may be
visible at the metaphysis.
The epiphysis may be
compressed.
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27. In adults, scurvy must be differentiated from
Arthritis,
Hemorrhagic disorders,
Gingivitis, and
Protein-energy malnutrition.
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28. Patients should take ascorbic
acid at 100 mg 3-5 times a
day until total of 4 g is
reached, and then they
should decrease intake to
100 mg daily.
Divided doses are given
because intestinal absorption
is limited to 100 mg at one
time.
Parenteral doses are
necessary in those with
gastrointestinal
malabsorption.
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29. Diet
Foods high in vitamin C include the following.
Citrus fruits, especially grapefruits and lemons
Vegetables, including broccoli, green peppers,
tomatoes, potatoes, and cabbage
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30. The recommended daily allowance for vitamin
C varies.
The current recommendation for adults is
120 mg daily, although a dose of 60 mg daily
is all that is required to prevent scurvy.
Diets high in vitamin C have been claimed to
lower the incidence of certain cancers,
particularly esophageal and gastric cancers
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31. Taking >2 g of vitamin C in a single dose may result
in-
Abdominal pain,
Diarrhea, and nausea.
Since vitamin C may be metabolized to oxalate, it is
feared that chronic, high-dose vitamin C
supplementation could result in an increased
prevalence of kidney stones, thus it is reasonable to
advise patients with a past history of kidney stones to
not take large doses of vitamin C.
There is also an unproven but possible risk that
chronic high doses of vitamin C could promote iron
overload in patients taking supplemental iron.
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32. Vitamin C deficiency can occur as part of general
under nutrition, but severe deficiency (causing
scurvy) is uncommon.
Symptoms include fatigue, depression, and
connective tissue defects (eg, gingivitis, petechiae,
rash, internal bleeding, impaired wound healing). In
infants and children, bone growth may be impaired.
Severe deficiency results in scurvy, a disorder
characterized by hemorrhagic manifestations and
abnormal osteoid and dentin formation.
Diagnosis is usually clinical.
Treatment consists of oral vitamin C.
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