Cobalt, Serum (Sendout)

Useful For:

• Detecting cobalt toxicity
• Monitoring metallic prosthetic implant wear
• This test is not useful for assessment of vitamin B12 activity.

Patient Preparation: High concentrations of gadolinium and iodine are known to interfere with most metal tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.

Note: To ensure that specimens are not contaminated by the collection tubes, specimen vials, or other supplies, only use the supplies listed below. Use of supplies other than those indicated may produce falsely elevated results.

Interpretation:

Concentrations greater than or equal to 1.0 ng/mL indicate possible environmental or occupational exposure. Cobalt concentrations associated with toxicity must be interpreted in the context of the source of exposure. If cobalt is ingested, concentrations greater than 5 ng/mL suggest major exposure and likely toxicity. If cobalt exposure is due to orthopedic implant wear, there are no large case number reports associating high circulating serum cobalt with toxicity.

There are no Occupational Health and Safety Administration blood or urine criteria for occupational exposure to cobalt.

Prosthesis wear is known to result in increased circulating concentration of metal ions. Modest increase (4-10 ng/mL) in serum cobalt concentration is likely to be associated with a prosthetic device in good condition. Serum concentrations above 10 ng/mL in a patient with cobalt-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 US Food and Drug Administration recommends testing cobalt in EDTA anticoagulated whole blood in symptomatic patients with metal-on-metal implants.

Cautions:

Because this test uses mass spectrometry detection, the radioactive form of cobalt, (60)Co, is not quantified.

Specimen collection procedures for cobalt require special specimen collection tubes, rigorous attention to ultraclean specimen collection and handling procedures, and analysis in an ultraclean facility. Unless these precautions are taken, elevated serum cobalt results may be an incidental and misleading finding.

7 mL blood in ROYAL BLUE No-Additive Metal-Free blood collection tube (BD #368380 or Mayo Supply T184)

Unacceptable: Any other tube type.

Resources: Mayo Metals Analysis Specimen Collection and Transport

Outside Laboratories:

• Obtain the required materials: Royal blue-top trace element blood collection tube (BD #368380 or Mayo Supply T184) and Mayo Metal-free Specimen Vial (T173).
• After collection, allow the specimen to clot for 30 minutes; then centrifuge the specimen to separate serum from the cellular fraction.
• Remove the stopper. Carefully pour specimen into a Mayo metal-free, polypropylene vial, avoiding transfer of the cellular components of blood. Do not insert a pipet into the serum to accomplish transfer, and do not ream the specimen with a wooden stick to assist with serum transfer.
• Refrigerate serum.

Stability: Refrigerated (preferred) 28 days; Frozen 28 days; Ambient 28 days.

1. Allow the specimen to clot for 30 minutes; then centrifuge the specimen to separate serum from the cellular fraction.
2. Remove the stopper and carefully pour serum into a 7-mL, Mayo metal-free, screw-capped, polypropylene vial (Supply T173), avoiding transfer of the cellular components of blood. Do not insert a pipet into the serum to accomplish transfer, and do not ream the specimen with a wooden stick to assist with serum transfer.
   • Note: Samples not submitted in a Mayo metal-free vial are acceptable, but not preferred, since results may be falsely elevated.
3. Refrigerate serum.

Sendouts:

• Order Mayo Test: COS
• Interfaced: Yes [Interface: 601; Department: MARF]

Stability: Refrigerated (preferred) 28 days; Frozen 28 days; Ambient 28 days.