Metals, toxins and medication
Kwik
Mercury in urine shows how much mercury your kidneys excrete; it is mainly informative after exposure to mercury vapor.
Everything about this testWhat it measures
The analysis measures how much mercury leaves the body in the urine. The kidneys mainly excrete metallic and inorganic mercury, the kind of mercury released from vapor, for example from a broken thermometer or from old dental fillings. Organic mercury from fish, on the other hand, barely ends up in the urine. The result is therefore a measure of excretion, not of a store in the body.
- Exposure to mercury vapor or to inorganic mercury, for example through work or after an accident with mercury
- Monitoring excretion in someone who has been diagnosed with mercury poisoning
High
A raised value fits exposure to mercury vapor or inorganic mercury. The level does not tell exactly how much mercury someone has taken in. A raised excretion without symptoms also does not mean there is damage. Symptoms that go with long-term exposure include kidney problems, tingling or trembling, and problems with seeing, hearing, smelling or tasting.
Low
A low or unmeasurable value is normal. The body does not need mercury, so there is no such thing as a mercury deficiency. A low value does not rule out exposure to mercury from fish, because that kind of mercury is barely excreted in the urine.
If your result is abnormal
With a raised result, the GP looks for the source of the exposure and has the measurement repeated if needed, preferably in urine collected over 24 hours. If real poisoning is suspected, referral follows to a doctor with knowledge of poisoning.
Reliability
Mercury in urine is mainly informative with a known exposure to mercury vapor or inorganic mercury; in people without known exposure, a single value says little. The meaning of a slightly raised excretion in someone without symptoms has been little studied. A single urine sample varies strongly with how much you drink; that is why the result is usually corrected for the creatinine content or measured in urine collected over 24 hours. The result says something about exposure, not about a buildup that you can remove with a course of treatment.
Limitations
- A single urine sample depends strongly on fluid intake; drinking a lot dilutes the result.
- Correction for creatinine or collection over 24 hours is needed to be able to compare values; with an incomplete collection, the result is not correct.
- Mercury from fish is barely excreted in the urine, so this test largely misses that form of exposure.
- There are no agreed cutoff values; the limit between normal and raised comes from the laboratory itself.
How common is this
Mercury poisoning is rare in the Netherlands. Most exposure at home comes from breaking a mercury thermometer, barometer, blood pressure monitor or energy-saving lamp. Exposure through work has decreased sharply because of regulations.
Who is this useful for
Useful with a known exposure to mercury vapor, for example after an accident or with work involving mercury, and with symptoms that suggest mercury poisoning. In people without symptoms and without known exposure, the measurement adds nothing. A normal result neither explains nor disproves existing symptoms.
Downsides and risks
- A diluted or, conversely, concentrated urine sample can give a raised or low result that has nothing to do with exposure.
- A slightly raised value without symptoms easily leads to worry and to unnecessary follow-up testing.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results