A 24-year-old woman is evaluated in the hospital for dyspnea, weight gain, constipation, and “feeling cold,” which have progressed over the last 3 weeks. She has been admitted to the hospital for 8 weeks for an exacerbation of Crohn disease and has been gradually improving with parenteral nutrition and immunosuppressants. Past medical history is otherwise unremarkable. Vital signs are within normal limits. Physical examination is significant only for a well-healing abrasion on her left leg that she sustained when she bumped the edge of the hospital bed while ambulating in the hospital room. Laboratory studies indicate an elevated TSH and normal glucose. Complete blood count and chemistry panel are within normal limits. Echocardiogram reveals dilated cardiomyopathy.
This patient is most likely experiencing which of the following micronutrient derangements?
D) Selenium deficiency
Selenium is necessary for the function of selenoproteins, which are critical in maintaining thyroid function and cardiac structural integrity. Selenium deficiency may therefore manifest with hypothyroidism and/or dilated cardiomyopathy. Immune dysfunction may also be observed. Individuals receiving parenteral nutrition are at elevated risk for selenium deficiency.
Answer choice A: Chromium deficiency, is incorrect. Inadequate chromium results in insulin tolerance and impaired glucose control. Patients with chromium deficiency may present with symptoms of hyperglycemia, including abdominal pain, urinary frequency, and polydipsia. This patient’s normal glucose level argues against chromium deficiency.
Answer choice B: Copper deficiency, is incorrect. Inadequate copper stores may present with brittle hair, fragile skin with depigmentation, muscle weakness, microcytic anemia, and osteoporosis. Genetic copper deficiency may result from mutations in the ATP7A gene which results in inadequate copper absorption and is known as Menkes disease.
Answer choice C: Manganese toxicity, is incorrect. Manganese toxicity is typically seen in individuals who work in the mining industry or as smelters/welders. Excess manganese manifests initially with psychiatric symptoms and ultimately progresses to neurological symptoms similar to Parkinson disease. Obstructive lung disease may also be observed.
Answer choice E: Zinc deficiency, is incorrect. Zinc is required in the zinc finger motif of collagenase, which is required to replace type III collagen with type I collagen in wound healing. Because of this, zinc deficiency is predominantly characterized by impaired skin integrity and wound healing. In infants, this can manifest as acrodermatitis enteropathica. Inadequate zinc stores may also present with hypogonadism, alopecia, immune dysfunction, dysgeusia (impaired taste), and anosmia (impaired smell). This patient’s adequate wound healing argues against zinc deficiency.
Key Learning Point
Selenium deficiency can present with thyroid insufficiency and cardiomyopathy. Individuals who are receiving parenteral nutrition, who are status post gastric bypass surgery, or who have other diet related diseases such as phenylketonuria are at elevated risk for micronutrient deficiencies.
