Commentary

Copper is an essential nutrient, readily available in the diet and rapidly absorbed through the gastrointestinal tract. Copper is abundant in dietary foods and water sources, and copper deficiency in humans is therefore uncommon. Nevertheless, acquired copper deficiency may occur when gastrointestinal uptake is impaired. The most common manifestations of copper deficiency are a decreased serum ceruloplasmin and anemia, neutropenia, or thrombocytopenia. If prolonged, copper deficiency will produce neurologic signs and symptoms that include sensory ataxia, hyperreflexia, and a spastic gait. If the deficiency is detected early, copper supplementation always resolves the serum and hematologic manifestations and prevents further neurologic deterioration. Neurologic recovery may be slow, however, and preferentially involves the sensory symptoms. Thus, copper deficiency is an important clinical problem that must be recognized early by the physician.

This case report raises several fascinating clinical issues. The reported findings are similar to those observed in patients with megaloblastic anemia and subacute combined degeneration due to vitamin B₁₂ deficiency. The mechanisms of bone marrow dysplasia and neurologic degeneration in copper deficiency are unknown, and these findings remind us of the unexplored relationship between cobalamin and copper metabolism. This patient was also reported to have increased serum zinc, presumably from chronic ingestion of dental adhesive. Zinc ingestion is associated with copper deficiency, and patients have been identified with acquired copper deficiency of unknown etiology and increased serum zinc in the absence of exogenous zinc ingestion. These findings remind us that we have much to learn about the interplay of copper and zinc homeostasis and suggest that the resulting copper deficiency is likely more complex than the proposed interference with gastrointestinal tract absorption.

In the final analysis, case reports of rare diseases sharpen our diagnostic skills and reveal the hidden mysteries that remain to be explored in much of human physiology and disease.

• Received for publication March 11, 2011.
• Accepted for publication March 21, 2011.

• © 2011 The American Association for Clinical Chemistry