Test Category: Specialist Biochemistry
Investigation Name:Cobalt – Joint fluid
Alias or Abbreviation:Fluids Co
Accreditation:UKAS ISO15189:2022 Accredited test: On scope
Intro:
In some individuals with metal-on-metal (MoM) replacement hip joints, and similar prostheses, it has become evident that release of metal debris from the devices may occur, leading to elevated blood metal ion concentrations and local soft tissue reactions. These can result in destruction of nearby muscle and bone and in a small number of cases, complete failure of the joint.The MHRA recommends monitoring of blood cobalt and chromium in all patients with MoM hip joints, with the frequency of monitoring depending on the risk.
Cobalt and chromium may also be measured in the synovial fluid surrounding the prosthetic joint to assess the wear on the joint. This is not indicated for most patients with a MoM replacement hip joint but may occasionally be useful, in combination with imaging, in difficult cases to assess the amount of wear on the joint or, if a patient has bilateral hip prostheses and it is not clear which hip joint is the most affected.
Pathology Laboratory:Trace Elements Laboratory
Requestable Seperately?Yes
Units:nmol/L
Minimum Sample Volume:1.5 mL joint fluid (may be used for measurement of both cobalt and chromium)
Expected Turnaround Time:14 working days.
Urgent analysis where clinically indicated may be arranged directly with the laboratory.
Test Code:COJF
Sample Type:
Joint fluid collected into a universal container.Complex Reference Range:There are no reference ranges for joint fluid cobalt and chromium.
In most cases, where there is significant wear on the MOM joint, Co and Cr concentrations will be very high (e.g., >1000 nmol/L).
It is common to see exceedingly high joint fluid Co and Cr results in excess of 100,000 nmol/L. However, such concentrations do not relate to blood concentrations of the metals or to systemic toxicity.
Referred to Another Laboratory?No
Storage Requirements:Store at 4 °C prior to dispatch
Posting Address / Requirements:1st class post at ambient temperature.
Sandwell Health Campus,
Pathology Laboratory,
Specialist chemistry,
Lyndon,
B71 4HJ
NPEX / PDF Reporting Available:Yes
EQA Scheme:No specific scheme available for this matrix, however we participate in UK NEQAS for Trace Elements for blood cobalt and chromium, and in the UK NEQAS for Trace Elements, Solid Matrix Scheme for sample digestion processes.
Further information:We are a designated Supra-Regional Assay Service (SAS) Laboratory for Trace Elements.
Lead Contact Details:Dr Nicola Barlow, Consultant Clinical Scientist,
SAS Director Trace Elements Laboratory
Email: nicola.barlow1@nhs.net
Email Address For Chasing Results:rwh-tr.bcpsspecialistchemistryenquiries@nhs.net
Methodology:Inductively coupled plasma mass spectrometry
Site Sample Tested:Sandwell Health Campus
Cost:Please email: bcpspathology.info@nhs.net for further details
Contact Number:Tel: 0121 507 5162
