What can a cobalt or chromium blood test tell you after a metal-on-metal hip?

What the test can tell you

SCENIHR (2014) recommended whole blood, with cobalt as the reference substance. Additional imaging was recommended when cobalt was above a threshold inside 2 to 7 µg/L. Critical values for systemic effects were not established. SCENIHR PDF.

FDA says surgeons should consider metal-ion measurement in symptomatic patients, ideally in series, together with imaging and the clinical picture. FDA says evidence is insufficient to recommend testing when the patient has no signs or symptoms and the surgeon finds a well-functioning implant with normal radiographs. FDA recommends EDTA whole blood and a validated ICP-MS method able to measure as low as 1 µg/L for cobalt, and the same floor if chromium is measured. FDA says a metal-ion level in isolation has not been shown to correlate with localized lesions, clinical outcomes, or the need for revision. FDA testing page.

MHRA MDA/2017/018 says rising levels may indicate potential for soft-tissue reaction and that MARS MRI or ultrasound should carry more weight than an isolated blood level. MHRA alert.

What it cannot tell you

It cannot, on these sources, serve as the only reason to revise an implant. Ordinary NHANES blood cobalt in 2017 to 2018 had a 95th percentile of 0.430 µg/L, which is below the SCENIHR concern range. That comparison is descriptive. It is not a diagnostic cutoff.

Related pages

• Cobalt
• Metal-on-metal hips as an exposure

Sources

1. SCENIHR opinion on metal-on-metal joint replacements, 2014
2. FDA, Information about Soft Tissue Imaging and Metal Ion Testing
3. MHRA MDA/2017/018
4. CDC National Report data tables (blood cobalt)

Heavy Metal Index

Heavy Metal Index: Cobalt. This Heavy Metal Index URL returned HTTP 200 on 15 October 2026. Figures on this page are not copied from that index. They come from the sources named above.