A 46-year-old man comes to the emergency department due to recurrent nosebleeds. When interviewed for additional history, he becomes belligerent and uncooperative. The patient has a history of alcohol use disorder and chronic mental illness. He has been placed in homeless shelters on multiple occasions but has not remained there for any prolonged periods. Physical examination shows swollen gums, scattered ecchymoses, and hyperkeratosis. He also has a chronic ulcer on the left lower extremity that does not appear to be infected. Which of the following mechanisms accounts for this patient's examination findings?

Question

A 46-year-old man comes to the emergency department due to recurrent nosebleeds.  When interviewed for additional history, he becomes belligerent and uncooperative.  The patient has a history of alcohol use disorder and chronic mental illness.  He has been placed in homeless shelters on multiple occasions but has not remained there for any prolonged periods.  Physical examination shows swollen gums, scattered ecchymoses, and hyperkeratosis.  He also has a chronic ulcer on the left lower extremity that does not appear to be infected.  Which of the following mechanisms accounts for this patient's examination findings?

Quizplus · Accepted Answer

11ec160b_36ed_85bf_9249_8705419f0530_MD0001_00 In the United States, vitamin C deficiency (scurvy) is most often seen in severely malnourished individuals (eg, homelessness, alcohol or substance use disorder). Symptoms of vitamin C deficiency are the result of decreased connective tissue strength. The capillary walls are especially fragile, leading to easy bruising, mucosal bleeding, and perifollicular petechial hemorrhages. Patients may also suffer from periodontal disease (gum swelling, loosening of the teeth, and infection) and poor wound healing, and have hyperkeratotic follicles with corkscrew hairs. Scurvy is even more severe in children and manifests with hemorrhages, bony deformities, and subperiosteal and joint hematomas. Vitamin C is necessary for the hydroxylation of proline and lysine residues during collagen synthesis. This reaction is executed by prolyl and lysyl hydroxylases, with vitamin C serving as a reducing agent. Hydroxyproline and hydroxylysine are essential for cross-linking collagen molecules. In scurvy, collagen cross-linking is compromised, thereby greatly reducing its tensile strength. (Choice A) Thiamine (vitamin B₁) serves as a coenzyme in the decarboxylation reactions mediated by several dehydrogenase enzymes. It is necessary for the conversions of pyruvate to acetyl-CoA and of alpha-ketoglutarate to succinyl-CoA in the citric acid cycle. Vitamin B₁ deficiency can cause peripheral neuropathy, heart failure, and central nervous system dysfunction (Wernicke-Korsakoff syndrome). (Choice C) Vitamin B₆ (pyridoxine) serves as a cofactor in many reactions that involve amino acids (eg, transamination, decarboxylation, deamination). Pyridoxine deficiency manifests with seborrheic dermatitis, glossitis, and peripheral neuropathy. (Choice D) Vitamin B₁₂ is necessary for the synthesis of methionine from homocysteine and for the synthesis of succinyl-CoA from methylmalonyl-CoA. Deficiency of vitamin B₁₂ causes megaloblastic anemia and subacute combined degeneration of the spinal cord. (Choice E) Purine and thymidine synthesis is diminished in patients with folate deficiency. The resultant decreased ability of erythropoietic cells to form DNA causes megaloblastic anemia. Educational objective: Vitamin C is necessary for the hydroxylation of proline and lysine residues in pro-collagen. Vitamin C deficiency (scurvy) is most often seen in severely malnourished individuals and leads to capillary bleeding, poor wound healing, and periodontal disease. In children, bony deformities and subperiosteal hemorrhages are also characteristic. __________ References: Scurvy masquerading as leukocytoclastic vasculitis: a case report and review of the literature. (http://www.ncbi.nlm.nih.gov/pubmed/16315563)

A 46-Year-Old Man Comes to the Emergency Department Due to Recurrent