Specimens from unexposed individuals collected using metal-free collection procedures typically have chromium above 0.3 ng/mL. Chromium is present in our environment at 100-fold to 1,000-fold higher concentration than found in biological tissues. Reports of increased serum chromium could be due to external contamination. Metal-free serum collection procedures must be followed, and centrifuged serum must be aliquoted into a Mayo Clinic Laboratories metal-free vial to avoid external contamination. Specimens collected using an anticoagulant are unacceptable; trace amounts of chromium are present in anticoagulants used in evacuated collection tubes.
Results greater than the flagged value indicate clinically significant exposure to chromium (Cr) (see Cautions about specimen collection). The reported units of measurement for chromium of ng/mL is equivalent to mcg/L.
Prosthesis wear is known to result in an increased circulating concentration of metal ions. A modest increase (0.3-0.6 ng/mL) in serum Cr concentration is likely to be associated with a prosthetic device in good condition. Serum concentrations above 1 ng/mL in a patient with a Cr-based implant suggest significant prosthesis wear. Increased serum trace element concentrations in the absence of corroborating clinical information do not independently predict prosthesis wear or failure. However, the FDA recommends testing chromium in EDTA anticoagulated whole blood in symptomatic patients with metal-on-metal implants.