OVERVIEW oF SCURVY
- Vitamin C (ascorbic acid):
- An essential water-soluble vitamin (humans cannot synthesize it).
- Found in citrus fruits, tomatoes, potatoes, cabbage, spinach, Brussels sprouts, cauliflower, broccoli, strawberries.
- Scurvy may appear after ~3 months of a vitamin C–free diet.
BIOCHEMICAL ROLE
- Ascorbic acid is the enolic form of α-ketolactone.
- Functions as a cofactor/cosubstrate in reactions using iron or copper (provides reducing equivalents).
- Key enzymatic processes include:
- Collagen synthesis (hydroxylation of proline & lysine residues).
- Carnitine synthesis (cofactor).
- Conversion of dopamine to norepinephrine (dopamine β-hydroxylase).
- Absorption: Takes place in jejunum and ileum; blood levels are regulated by renal excretion.
SCURVY
Definition & History
- Nutritional deficiency disorder caused by lack of vitamin C.
- Known since antiquity; historically linked to prolonged sea voyages with no fresh food.
- Dr. James Lind (1754) linked intake of oranges/lemons to preventing scurvy.
Clinical Features
- General Symptoms:
- Onset is insidious.
- Weakness, malaise, shortness of breath.
- Bone pain, myalgias, arthralgias, edema, neuropathy.
- Vasomotor instability.
- Skin & Connective Tissue:
- Impaired collagen → defective wound healing.
- Hyperkeratotic papules, perifollicular hemorrhages, follicular hyperkeratosis (coiled/frayed hair).
- Petechial hemorrhages (often start on lower extremities).
- Rumpel-Leede sign (abnormal capillary fragility): inflating BP cuff causes many petechiae.
- Large ecchymoses or even proptosis from retrobulbar hemorrhage.
- Subungual “splinter” hemorrhages.
- Joints & Bones:
- Hemorrhage into joints → pain, swelling, limited movement.
- In infants: subperiosteal hemorrhages → “frog leg” posture, “pseudoparalysis” from pain.
- Impaired osteoblast function → stunted growth in children.
- Gingival Changes:
- Gums become swollen, reddish-blue, spongy, friable.
- Loosening/falling of teeth.
- Severe Cases:
- Possible massive cerebral hemorrhages with hyperpyrexia, tachycardia, cyanosis, hypotension, Cheyne-Stokes respirations, leading to death.
DIAGNOSIS
- Scurvy is seen in severely malnourished individuals (e.g., certain alcoholics).
- Laboratory: Serum ascorbic acid level <0.3 mg/dL indicates severe deficiency (normal: 0.6–2.0 mg/dL).
TREATMENT
- Ascorbic acid supplementation:
- Typically 500 mg/day until resolution of signs/symptoms.
- Address underlying causes of dietary deficiency or malabsorption.
PREVENTION
- Recommended daily allowance:
- Men: 90 mg/day
- Women: 75 mg/day
- Pregnant/Lactating women: ~120 mg/day
- Achievable with balanced diets including citrus fruits and vegetables.