VITAMIN C DEFICIENCY (SCURVY)

Scurvy is well-defined acute manifestation of vitamin C deficiency, though mild or subclinical deficiency states may present with impaired wound healing, bleeding gums, mild anemia and susceptibility for infections.

Physiology: Vitamin C or ascorbic acid (Table 6.16) is a water-soluble vitamin and hence not stored in the body and rapidly excreted in urine.

RDA of vitamin C is ~20-45 mg/day in children and 50-85 mg in adolescents, higher during infections and fever as it is not stored in body.

TABLE 6.16: Vitamin C at a glance

RDA: 20-85 mg/day

(Higher in infections e.g. fever, diarrhea)

Sources:

• Richest source: Amla (600 mg)

• Citrus Fruits: Guava (212 mg), orange, lemon, pineapple

• Vegetables: Cabbage (124 mg), tomato, green vegetables.

• Germinated pulses

• Non-veg foods, e.g. liver and kidneys (not in meat)

Functions:

• Essential for collagen formation

• Wound healing and epithelial integrity

• Facilitate iron absorption and folate metabolism

• Antioxidant effect

Deficiency states:

• Typical: Scurvy

• Others: Poor wound healing, anemia, recurrent infections

Dietary sources: Breastfeeding is an adequate source of vitamin C in early infancy. Citrus fruits, leafy vegetables and germinated seeds are rich sources of vitamin C. However, it is extremely heat-labile, rapidly inactivated on cooking and extrudes in cooking-water. Milk products and lean meat are poor sources of vitamin C.

Functions: Vitamin C essential for synthesis of: (a) normal collagen by incorporating proline and hydroxyproline, and (b) chondroitin sulphate - a component of inter­cellular matrix required for epithelial integrity and wound healing. It also facilitates, (c) iron absorption,

(d) folate metabolism (conversion of folic acid into folinic acid), and (e) elimination of toxic-free radicals (antioxidant).

Vitamin C Deficiency (Scurvy)

Etiology: Scurvy is usually precipitated by sudden increase in vitamin C requirements due to infections, acute febrile illnesses, diarrhea, etc. in children with subclinical dietary deficiency, e.g. in undernutrition or top feeding. Wrong cooking practices, e.g. over­boiling of vegetables in excess water or throwing the excess cooking-water are important causes of dietary deficiency.

Clinical manifestations: Scurvy usually presents in late infancy or in toddlers, following an infective episode, e.g. diarrhea or viral infection in malnourished children. A typical case present with:

• Skeletal signs:

- Pseudoparalysis—severe tenderness and restricted limb movements with pithed-frog posture

- Scorbutic rosary—tender, sharp, nodular beading at costochondral junktions, due to subluxation rib epiphyses at sternal joints.

• Skin/mucosal signs:

- Swollen, purple, bleeding gums,

- Petechial/ecchymotic perifollicular hemorrhages over skin and mucus membranes. Severe gastro­intestinal or intracranial bleeds are rare.

• Mental changes:

- Apprehensive facial appearance

- Extreme irritability or apathy

• Signs of subclinical deficiency:

- Poor wound healing

- Moderate dimorphic anemia

- Increased susceptibility for infections

Diagnosis of scurvy depends on:

• Suggestive clinical features with history of precipi­tating event, e.g. fever or diarrhea;

• Characteristic radiological finding, best seen at the end of long bones at knee joint (Fig. 6.8) and include:

- Ground-glass appearance of the shaft and epiphysis due to loss of trabecular pattern,

- Thinning or penciling of cortex with sharply outlined epiphyseal ends,

- Wimberger's ring sign-ground-glass appearance of epiphyseal centers, surrounded by a white ring of compressed collagen,

- White line of Frankel—a thick, irregular, transverse, white line at epiphyseal ends due to thickened provisional zones of calcification.

- Trummerfeld zone of rarefaction—a narrow zone of metaphyseal rarefaction proximal to Frankel's line, due to atrophy of subepiphyseal cortex.

- Angle sign—a triangular, rarefied, lateral defect proximal to Frankel's line, representing early stage of the zone of rarefaction.

Fig. 6.8: Scurvy: X-ray

X-ray knee showing: 1. Ground glass matrix, 2. Pencil-thin cortex,

3. Ring sign, 4. Frankel's line, 5. Zone of rarefaction, 6. Angle sign,

7. Pelkan spar. Inset: Subperiosteal hematoma

- Corner sign or Pelkan spur—a lateral spur-like growth of Frankel's line, due to compression of soft shaft.

- Lifting or separa tion of periosteum from the cortex due to sub-periosteal hematoma. Actual hematomas are visible only after 1-2 weeks of illness as enveloping- shell appearance, due to calcification.

• Biochemical diagnosis is required only in sub-clinical cases, based on low ascorbic acid levels in a buffy coat (WBCs) sample of oxalate blood (Normal: 25-40 mg/ dl). A level of zero in this layer indicates scurvy, even without clinical signs. Plasma ascorbic acid levels are unreliable, though fasting levels gt;0.6 mg/dl exclude scurvy. Urinary excretion of gt;80% of dose after 3-5 hours of a loading dose of 100 mg/kg vitamin C, indicates no vitamin C deficiency.

D/D: Scorbutic bony lesions need to be differentiated from other cases of pseudoparalysis, e.g. (a) osteomyelitis/ septic arthritis, (b) transient synovitis, (c) trauma, (d) congenital syphilis, and (e) leukemic bone involvement.

Scorbutic rosary is different from rachitic rosary as it is: (a) tender, and (b) has sharper margins vs. rounded contour of the rachitic beading.

Treatment: Vitamin C therapy (PO 200-500 mg/day for a week) is highly effective with dramatic clinical recovery within 24-48 hours, though radiological improvement may take many weeks. Recurrence must be prevented by adequate diet and therapeutic supplementation (100 mg/day) for many weeks.

Prevention includes nutritional counseling, correct cooking practices and vitamin C supplementation in lactating mothers, top-fed infants and during acute infective illnesses.

Vitamin C excess: Being a water soluble vitamin with free urinary excretion, large doses of vitamin C are well tolerated though some studies have shown higher risk of renal stones and iron load after excess vitamin C intake for long periods.

6.4