What this test measures
Cobalt is the central atom of vitamin B12 (cobalamin), but free cobalt has its own toxicology distinct from B12. Blood / serum cobalt is the standard test. Levels rise after prolonged contact with metal-on-metal hip implants (which release cobalt and chromium ions through wear), occupational exposure (hard-metal tool manufacturing, cobalt mining), or rare dietary contamination.
Why it matters
In India, the main clinical use is monitoring patients with metal-on-metal hip prostheses — rising serum cobalt suggests implant wear / failure and is on the WHO and MHRA surveillance algorithms (typical action level 7 µg/L). Occupational exposure to cobalt dust causes "hard-metal lung" interstitial fibrosis. Rarely, cobalt supplements (sometimes marketed as B12 boosters) or contaminated beer (the historical Quebec cobalt cardiomyopathy outbreak) cause systemic toxicity — polycythaemia, hypothyroidism, cardiomyopathy, peripheral neuropathy.
How to prepare
No fasting required. Collect into a trace-metal-free royal-blue-top tube. Disclose any joint replacements (metal-on-metal vs ceramic-on-polyethylene) and occupational exposure. Stop B12 injections / supplements 48 hours before — though cobalamin assays do not directly cross-react, very high doses can affect total cobalt slightly.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Serum / Blood Cobalt (µg/L)[1][2] | < 1.0 (no metal implants); < 7 (metal-on-metal hip target) | Low / undetectable — no significant exposure. Expected in the general population. | 1–7 µg/L (with hip implant): low-grade ion release, monitor 6-monthly. > 7 µg/L (with hip implant): MHRA threshold for further investigation (cross-sectional MARS-MRI imaging, clinical review). > 20 µg/L: significant exposure — often associated with adverse local tissue reaction, possible systemic effects. > 100 µg/L: severe — implant revision often required; risk of cardiomyopathy, hypothyroidism, neuropathy. |
Cobalt levels with metal-on-metal hip implants
| Cobalt (µg/L) | Implant context | Action |
|---|---|---|
| < 1 | No implant | Normal background |
| 1 – 7 | MoM hip — low-grade ion release | 6-monthly monitoring |
| 7 – 20 | MoM hip — investigate | MARS-MRI / cross-sectional imaging; orthopaedic review |
| 20 – 100 | Implant failure likely | Plan revision; systemic toxicity screening |
| > 100 | Severe systemic exposure | Urgent revision; cardiac, thyroid, neuro evaluation |
Frequently asked questions
Why is cobalt tested with chromium for hip replacements?
Metal-on-metal hip prostheses release both cobalt and chromium ions through wear. Most centres measure both at the same time as a pair (cobalt is usually higher than chromium and rises earlier).
Can high cobalt affect the thyroid?
Yes — chronic high cobalt can cause hypothyroidism. The historical "beer-drinker's cardiomyopathy" outbreak in Quebec in the 1960s (cobalt added to beer foam) caused thyroid suppression and cardiac failure.
Will my B12 injections raise cobalt?
Therapeutic B12 doses raise cobalt slightly but not into the action range. Disclose B12 dosing so the result is interpreted correctly.
What is MARS-MRI?
Metal Artefact Reduction Sequence MRI — a special MRI protocol used to image around metal hip implants and assess for adverse local tissue reaction (pseudotumour, fluid collections).
Are ceramic hips also a concern?
No. Ceramic-on-polyethylene and ceramic-on-ceramic hips release negligible cobalt — surveillance of metal ions is only required for metal-on-metal designs.
Related Toxicology / Trace Elements tests
Tests commonly ordered alongside COBALT, or that help interpret an unexpected result.
Sources & references
- ATSDR — Toxicological Profile for Cobalt · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Labs — Cobalt, Blood · accessed 2026-05-30T00:00:00.000Z
- WHO — Cobalt and Inorganic Cobalt Compounds · accessed 2026-05-30T00:00:00.000Z
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