Zinc in denture adhesive: a rare cause of copper deficiency in a patient on home parenteral nutrition.

A 65-year-old woman with Crohn's disease, who had been on home parenteral nutrition for many years, presented with perioral paraesthesia and a burning sensation in the mouth. Initial blood tests including serum ferritin, vitamin B12 and folate, were normal apart from mild pancytopaenia. Serum copper was low, in spite of receiving regular copper in her parenteral feeds. The copper in her parenteral feeds was increased initially, but when it did not improve, she was started on weekly intravenous copper infusions. She was using dental adhesive, which had zinc in it, and a possibility that this was causing her copper deficiency was raised. Serum zinc levels were normal, but urinary zinc was very high. The patient was advised to use zinc-free dental adhesive and her copper level returned to normal within a few months with normalisation of her pancytopaenia, and partial resolution of her oral paraesthesia.