Histology · Year 1 · from Histology
Case 2: Scurvy (Vitamin C Deficiency)
Clinical Image
Source: Wikipedia - Scurvy - Public Domain
Case Presentation
A 58-year-old homeless man is brought to the emergency department by outreach workers who noticed he was having difficulty walking. He reports a diet consisting almost exclusively of processed foods and alcohol for the past several months. Physical examination reveals swollen, purple, spongy gums that bleed spontaneously, multiple petechiae and ecchymoses over his lower extremities, perifollicular hemorrhages with "corkscrew" hairs, and painful swelling of his legs. He has lost several teeth recently. Laboratory studies show a plasma vitamin C level of <0.1 mg/dL (normal >0.4 mg/dL). A diagnosis of scurvy is made. The pathophysiology is explained: without vitamin C (ascorbic acid), prolyl and lysyl hydroxylase enzymes cannot function, preventing proper hydroxylation of proline and lysine residues in procollagen. The resulting collagen cannot form stable triple helices and is rapidly degraded. Treatment with vitamin C supplementation leads to dramatic improvement within weeks.
Key Learning Points
- Vitamin C is an essential cofactor for prolyl and lysyl hydroxylase enzymes in collagen synthesis
- Hydroxyproline and hydroxylysine residues are critical for stable triple helix formation and cross-linking
- Without stable collagen, blood vessel walls become fragile (causing bleeding), wound healing is impaired, and teeth loosen (weakened periodontal ligament)
- Scurvy demonstrates the critical importance of post-translational modifications in collagen biosynthesis