As with other trace elements, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is used for the detection of cobalt in biological specimens.
Blood/plasma/serum:
Like with chromium, cobalt testing is not common. It is most commonly seen in the workup of possible joint failures in prostheses that contain cobalt alloys. Above normal levels of cobalt in blood or serum indicate possible environmental or occupational exposure or can be due to orthopedic implant wear. Different concentration cutoff levels have been proposed for patients with normal prosthesis wear versus more significant wear.
Urine cobalt:
Elevated concentrations indicate excess exposure to cobalt. It should be noted that no Occupational Safety and Health Administration (OSHA) blood or urine criteria can be used to define occupational exposure to cobalt. As with blood/plasma/serum, prosthesis wear can result in an increased circulating concentration of cobalt if the prosthesis contains cobalt. A modest increase in urine cobalt concentration is associated with a prosthetic device in good condition, whereas higher concentrations are consistent with more significant prosthesis wear or failure.
Whether to use 24-hour urine or a random ‘spot’ urine for trace element or heavy metal testing remains an area of debate. While 24-hour urine likely provides for greater sensitivity in that it collects more urine over a greater time (and so can account for any diurnal variation in excretion), it can also be more dilute than random urine collected in the morning (a first void specimen). Studies have shown modest correlation between 24-hour urine samples and random samples. Both specimen types are usually offered by reference labs.
