A 44-year-old woman comes to the clinic after several "near collisions" over the past month while driving at night. She also has generalized pruritus. The patient has not seen a physician for several years and has missed several scheduled appointments. She takes no medications. On physical examination, her skin is diffusely coarse and dry. Which of the following processes is most likely responsible for these findings?

Question

A 44-year-old woman comes to the clinic after several "near collisions" over the past month while driving at night.  She also has generalized pruritus.  The patient has not seen a physician for several years and has missed several scheduled appointments.  She takes no medications.  On physical examination, her skin is diffusely coarse and dry.  Which of the following processes is most likely responsible for these findings?

Quizplus · Accepted Answer

11ec160b_3ae8_f687_9249_89f31bb0d7de_MD0001_00 This patient's impaired driving in low light conditions ("night blindness") and thickened, dry skin (hyperkeratosis) are suggestive of vitamin A deficiency. Dietary intake of vitamin A comes from a combination of beta-carotene, a provitamin found in plants, and preformed vitamin A from animal sources. Vitamin A is necessary for vision (phototransduction, retinal and conjunctival development) and keratinocyte differentiation. Most individuals in the United States have adequate dietary intake of vitamin A, but patients may develop deficiency due to malabsorption related to biliary obstruction, exocrine pancreatic insufficiency, or small-bowel resection (eg, Crohn disease, bariatric surgery). This patient, a middle-aged woman with generalized pruritus and signs of vitamin A deficiency, likely has underlying primary biliary cholangitis (PBC), a common autoimmune disease characterized by destruction of small bile ducts in the liver. Bile acids are important for solubilization and absorption of fats; patients with chronic biliary obstruction due to PBC may develop malabsorption of fats and fat-soluble vitamins (A, D, E, and K). Patients with PBC frequently have generalized pruritus due to bile acid accumulation in the skin. Visible jaundice is often not apparent until later in the disease course. (Choices A and C) Inadequate exposure to sunlight can cause vitamin D deficiency in individuals without adequate dietary vitamin D intake. Chronic renal failure can also result in vitamin D deficiency due to reduced production of 1,25-dihydroxyvitamin D. (Choice B) Sickle cell disease is a form of chronic hemolytic anemia that can cause retinopathy due to microvascular occlusion, retinal ischemia, and neovascularization/hemorrhage. However, vision impairment would not be restricted to nighttime, and affected patients would likely have other vasoocclusive symptoms. (Choice E) Rheumatoid arthritis can cause episcleritis or scleritis, which usually presents with ocular discomfort rather than night blindness. (Choice F) A strict vegan diet can cause cobalamin, but not vitamin A, deficiency. Dietary deficiency of vitamin A is rarely seen in the United States and usually occurs in patients with highly unusual dietary patterns, severe mental illness, or alcohol use disorder. Educational objective: Vitamin A deficiency causes night blindness and hyperkeratosis. Deficiency of this fat-soluble vitamin can develop in patients with biliary disorders, exocrine pancreatic insufficiency, or intestinal malabsorption. __________ References: Vitamin A supplementation for cystic fibrosis. (http://www.ncbi.nlm.nih.gov/pubmed/24823814)

A 44-Year-Old Woman Comes to the Clinic After Several "Near