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PTD - 205

Test Directory -  Chromium / Colbalt

Available for monitoring as part of MDA alert regarding metal on metal hip replacements

Synonyms

Clinical Indications

Cobalt and chromium levels may be measured in patients implanted with MoM hip replacements (MDA alert (MDA/2010/033)) The MDA guidance is to:

follow up patients at least annually for five years postoperatively and more frequently in the presence of symptoms.

investigate patients with painful MoM hip replacements. Specific tests should include evaluation of cobalt and chromium ion levels in the patient’s blood and cross sectional imaging including MRI or ultrasound scan.

consider measuring cobalt and chromium ion levels in the blood and/or cross sectional imaging for the following patient groups:

 

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patients with radiological features associated with adverse outcomes including component position

 

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patients with small component size (hip resurfacing arthroplasty only)

 

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cases where the patient or surgeon is concerned about the MoM hip replacement

 

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cohorts of patients where there is concern about higher than expected rates of failure

if either cobalt or chromium ion levels are elevated above seven parts per billion (ppb), then a second test should be performed three months after the first in order to identify patients who require closer surveillance, which may include cross sectional imaging.

Cobalt and chromium may be available for nutritional screening/monitoring or occupational exposure assessment. These requests must be discussed with Consultant Biochemist (please note different sample types).

Request Form 

Combined Pathology Blood form (Yellow/Black or Blue for GP's)

Availability

Analysed by referral laboratory if specific criteria met.

Specific Criteria

Monitoring patients with MoM hip replacement or if agreed with Consultant Biochemist for nutritional or occupational exposure assessment

Patient Preparation

No specific preparation required

Turnaround Time

One week

Container

Second drawn blood into Dark Blue top (trace metal) tube for metal on metal hip replacement screening (DePuy). If no other sample types requested suggest collecting a yellow top (SST) tube 1st before the blue top tube.

Red top (plain) tube for nutritional screening/monitoring (very rarely requested)

Urine (white top) for occupational exposure (very rarely requested)

Causes for Rejection

Unlabelled sample
Not meeting specific criteria for analysis. 

Reference Range

 

MHRA guidelines (for MoM hip replacements):
Chromium 134 nmol/L (= 7 ug/L (ppm))
Colbalt 119 nmol/L (= 7 ug/L (ppm))

If either Chromium or Cobalt are elevated above these levels then a second test after 3 months is recommended in order to identify patients who require closer surveillance.

Unit Conversion

To convert from nmol/L to ug/L (ppm) multiply by:
Chromium nmol/L x 0.052 = ug/L (ppm)
Cobalt  nmol/L x 0.059 = ug/L (ppm)

Lab. Handling

Processing: Aliquot sample and store at 4°C in separating fridge(CB39).
Referral
: CRCO and send or BPRO and save at 4°C in separating fridge (CB39).

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Version 1.1 / July  2014                                                                                                           Approved by: Consultant Biochemist