Clinical significance of the laboratory determination of low serum copper in adults.

ABSTRACT

BACKGROUND: Low serum copper is often indicative of copper deficiency. Acquired copper deficiency can cause hematological/neurological manifestations. Wilson disease (copper toxicity) is associated with neurological manifestations and low serum copper, with copper deposited in tissues responsible for the toxicity. Low serum copper can also be observed in some carriers of the Wilson disease gene and aceruloplasminemia. This study was undertaken to determine the clinical significance of low serum copper. METHODS: The Mayo Medical Laboratories', Metals Laboratory database was reviewed over a 9-month period to identify patients who received their care at the Mayo Clinic and had low serum copper. The medical records were analyzed to determine the significance of the low copper. RESULTS: In six of the 57 patients with low serum copper, the low copper was due to Wilson disease. In the remaining 51 patients, copper deficiency due to an underlying cause was identified in 38 as a reason for the low serum copper. The most commonly identified neurological manifestation of copper deficiency was myeloneuropathy. Coexisting nutrient deficiencies and hematological manifestations of copper deficiency were often but not invariably present. CONCLUSIONS: Copper deficiency, Wilson disease (or a carrier state), and aceruloplasminemia are all associated with low serum copper. The presence of coexisting neurological or hematological manifestations that are recognized sequelae of copper deficiency should be considered prior to making a diagnosis of copper deficiency. Gastrointestinal disease or surgery is a common cause of acquired copper deficiency. Even in patients in whom low serum copper is indicative of copper deficiency, the cause of the copper-deficient state may not be evident.