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Test Category: Specialist Biochemistry

Investigation Name:Chromium- Blood

Alias or Abbreviation:Cr

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 regardless of the size of the implant or whether the patient is symptomatic. Annual monitoring is recommended for most groups with less frequent monitoring in low-risk groups. If the metal ion concentrations exceed the MHRA threshold of 135 nmol/L for chromium or 120 nmol/L for cobalt, repeat testing 3 months later is advised together with other further investigations (e.g., imaging studies).
It should be noted that, whilst elevated blood chromium and cobalt concentrations reflect varying degrees of wear to the hip implant, it is currently not possible to interpret these results with respect to any potential toxicity effects on the patient.

Pathology Laboratory:Trace Elements Laboratory

Requestable Seperately?Yes

Units:nmol/L

Minimum Sample Volume:500 µL whole blood

Expected Turnaround Time:7 working days.
Urgent analysis where clinically indicated may be arranged directly with the laboratory.

Test Code:CR

Sample Type:

Preferred: EDTA whole blood
Accepted: Trace element free sodium heparin whole blood
Note: Plasma/serum is NOT recommended for monitoring metal-on-metal hip patients

Complex Reference Range:<40 nmol/L

Collection Conditions / Other Information:It is not necessary to use an indwelling cannula when collecting the blood as the amounts of chromium and cobalt leaching from stainless steel needles has been found to be negligible.
A single 500 µL EDTA or sodium heparin whole blood sample may be used for measurement of both chromium and cobalt.
Plasma/serum is not recommended as there is a small risk that the separation process may contaminate the specimen. In addition, there is a marked difference in the normal chromium content of plasma and whole blood so it is important that the two types of specimen are not used interchangeably when serially monitoring patients.

Referred to Another Laboratory?No

Storage Requirements:Store at 4 °C prior to dispatch

Posting Address / Requirements:Ambient temperature, 1st class post.
Sandwell Health Campus,
Specialist Chemistry,
Pathology Department,
Lyndon, B71 4HJ

NPEX / PDF Reporting Available:Yes

EQA Scheme:UK NEQAS for Trace Elements

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:Email: bcpspathology.info@nhs.net for further details

Contact Number:0121 507 5162