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Cobalt - Ortho-blood

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Cobalt - Ortho-blood
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Reference Range:

See patient report

Turnaround Time:

5 days

Description:

Cobalt - Ortho-blood

Vessels and Containers:

Preferred sample type Whole blood Royal blue top trace elements free tube.
EDTA - purple top

Sample Requirements:

EDTA/Sodium Heparin : Minimum 2ml whole blood

Important Information:

Surgical implants
Much of the recent clinical interest in chromium and cobalt arises from the use of a chromium/cobalt/molybdenum alloy in orthopaedic implants, especially hip replacements. Chromium and cobalt and the main components of the alloys used in many of these implants, but other metals are also present. Chromium and cobalt are primarily released from wear on metal-on-metal surfaces. The most important of these is the surface between a metal cup in the pelvis and a metal ball. The release of metal is due to friction at the surface, which can be due to misalignment of the components and can lead to failure of the implant. If uncorrected there can be severe local tissue damage with formation of a ‘pseudo tumour’ and necrosis of soft tissue. There have been two warnings on these implants from the UK MHRA suggesting that patients may need to be followed up for the life of the implant. Recent evidence suggests that other surfaces may also contribute to metal release, especially the junction between the stem in the femur and the ball in modular implants. After revision surgery chromium concentrations may remain high for some considerable time due to chromium accumulation in soft tissue surrounding the implant, whereas cobalt does not accumulate.

The UK MHRA suggest that a concentration of 7 ug/L (118 nmol/L) is indicative of increased wear of the implant. Slightly lower concentrations have been proposed by other works and a European multidisciplinary group.

Cobalt has been implicated in a few rare cases of toxicity seen in these patients, primarily toxicity to sensory nerves, especially aural and visual effects. There has been some evidence that cobalt can cause toxicity in vitro. In almost all patients there is no evidence of toxicity from metal release in these patients. There has been some concern about possible carcinogenicity, but evidence to date suggests that there is no increased cancer risk in these patients.

The same alloys are used in other implants, such as knee and other joints, but the hip is the only implant with a metal-on-metal surface, so the metal release is less important in these implants.

Transportation and Handling:

Send by 1st Class Post

Time limits for requesting additional examinations:

Upto 2 weeks post original request