Cadmium (blood)

There is no level the body needs; UK labs print an upper limit for non-smokers of around 18 nmol/L (2 ug/L), smokers commonly run two to three times higher, and separate action levels apply to people exposed at work.

Cadmium is a metal with no role in the body that accumulates in the kidneys over decades. In the general population it comes mainly from cigarette smoke and from food grown on contaminated soil; at work it comes from batteries, pigments, plating and welding. Blood cadmium reflects recent exposure over the past few months, while urine cadmium reflects the lifetime store in the kidneys.

It is requested in people exposed at work under health and safety monitoring, when living near a contaminated site, and when unexplained kidney problems, bone pain or protein in the urine are being looked into. It is occasionally on private heavy-metal panels.

• Smoking, including passive smoking, which is the main source in the general population
• Work with batteries, pigments, plating, welding, soldering or recycling
• Food grown on contaminated soil, shellfish and offal, slightly
• Living near a smelter or on contaminated land
• Low iron stores, which increase how much cadmium the gut absorbs

• Stopping smoking, after which the blood level falls over months
• Ending the exposure at work
• A value below the cut-off is the expected finding

• Smokers commonly sit above the non-smoker cut-off
• Blood collected in a standard tube rather than a trace-element tube can be contaminated
• Blood and urine cadmium measure different things (recent exposure versus long-term store) and have different ranges

A whole blood EDTA sample in a trace-element tube, no fasting needed. Smoking status should be noted. Urine cadmium is added when the long-term body burden matters.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.