Vitamin C deficiency

By- Professor (Dr.) Namrata Chhabra
Biochemistry For Medics - Lecture Notes
www.namrata.co
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Biochemistry For Medics

 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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 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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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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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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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.
Biochemistry For Medics 8/30/2014 6

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.

 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.

 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

 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.

 Subperiosteal
hemorrhages,
sometimes
due to small
fractures, may
occur in
children or
adults.

 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.

 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.

 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.

Nails: Splinter
hemorrhages may occur.

Head and neck:
 Gum swelling, friability, bleeding, and
infection with loose teeth;
 mucosal petechiae;

 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.

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.

 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.

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.

 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

 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.

 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.

 In adults, scurvy must be differentiated from
 Arthritis,
Hemorrhagic disorders,
 Gingivitis, and
 Protein-energy malnutrition.

 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.

 Diet
 Foods high in vitamin C include the following.
Citrus fruits, especially grapefruits and lemons
Vegetables, including broccoli, green peppers,
tomatoes, potatoes, and cabbage

 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

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.

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.

Vitamin C deficiency

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