Pruritic Rash and Diarrhea

An 82-year-old woman reported 2 months of diarrhea and 2 weeks of pruritic rash on her extremities as well as a recent left radius fracture; she was malnourished but most laboratory parameters were normal except mild hyponatremia and levels of copper and zinc well below normal. What is the diagnosis and what would you do next?
Source: JAMA - Category: General Medicine Source Type: research