Blood Mercury Unit Converter
Blood Mercury Unit Converter
Convert whole blood mercury between µg/L, nmol/L and µg/dL, and read the result against the general-population upper limit.
Blood Mercury converter
Mass ⇄ molarWhole blood mercury 4 µg/L
Formula and conversion factor
µg/L = nmol/L ÷ 4.985
µg/dL = µg/L ÷ 10
- 4.985
- derived from the atomic weight of mercury, 200.59
- whole blood
- the correct specimen — methylmercury partitions into red cells, so serum or plasma underestimates the exposure
- half-life
- around 50 to 70 days for blood methylmercury, so a result reflects intake over the preceding two to three months
Worked example
Whole blood mercury 4 µg/L
4 × 4.985 = 19.9 nmol/L
= 0.400 µg/dL
Below the commonly quoted general-population upper limit of 5 µg/L, or about 25 nmol/L
Whole blood mercury in both units
| µg/L | nmol/L | Significance |
|---|---|---|
| 4 | 19.9 | Worked example — within the general-population range |
| 5 | 24.9 | Commonly quoted general-population upper limit |
| 10 | 49.9 | Take a full dietary and occupational history |
| 50 | 249.3 | Substantial exposure — specialist toxicology advice |
Blood and urine mercury answer different questions
| Whole blood mercury | Urine mercury | |
|---|---|---|
| Mainly reflects | Organic (methyl)mercury | Inorganic and elemental mercury |
| Usual source | Fish, especially large predatory species | Occupational vapour, dental amalgam work, skin-lightening creams |
| Specimen | Whole blood — mercury partitions into red cells | 24-hour or creatinine-corrected spot urine |
| Approximate half-life | 50 – 70 days | Weeks to months, renal accumulation |
Which mercury the blood test actually measures
Whole blood mercury in µg/L is converted to nmol/L by multiplying by 4.985, a factor that follows from the atomic weight of mercury, 200.59. µg/dL is µg/L divided by ten. The specimen matters as much as the unit: mercury partitions into red cells, so whole blood, not serum or plasma, is the correct sample, and a serum result will understate the exposure. Blood collected into a trace-element tube avoids the contamination that ordinary tubes can introduce.
Blood mercury mainly reflects recent organic mercury exposure — methylmercury from fish — and has a half-life of around 50 to 70 days, so a result describes intake over the preceding two to three months rather than a lifetime burden. Urine mercury, by contrast, reflects inorganic and elemental exposure, typically occupational vapour, some traditional remedies and imported skin-lightening creams. The two tests answer different questions and are not interchangeable; asking for the wrong one is the commonest reason a genuine exposure is missed.
The commonly quoted general-population upper limit is about 5 µg/L, roughly 25 nmol/L. It describes a population that eats fish rather than marking a threshold of harm. Levels above roughly 10 µg/L are worth a full dietary and occupational history. Large predatory fish are the usual source: swordfish, shark, king mackerel, marlin and tilefish concentrate methylmercury through the food chain, and tuna contributes most in populations that eat it often. Intake in pregnancy is the situation that carries the clearest risk, because methylmercury crosses the placenta and the developing nervous system is the sensitive target.
Management follows the source. For dietary methylmercury, the intervention is to change the fish eaten — not to stop eating fish, since the nutritional benefit is real, but to move towards smaller, shorter-lived species — and to re-test after a few months, by which time the level should have fallen appreciably. Chelation is reserved for symptomatic inorganic or elemental poisoning and has no established role in dietary methylmercury exposure, where it has not been shown to improve outcome.
Frequently asked questions
How do I convert blood mercury from µg/L to nmol/L?
Multiply by 4.985, derived from the atomic weight of mercury, 200.59. A whole blood mercury of 4 µg/L is 19.9 nmol/L. To convert to µg/dL, divide the µg/L figure by ten.
Why is whole blood the right specimen?
Mercury partitions into red cells, so a serum or plasma result understates the exposure. Whole blood collected into a trace-element tube is the correct sample, and the tube matters because ordinary tubes can contribute contamination.
What is a normal blood mercury level?
The commonly quoted general-population upper limit is about 5 µg/L, or roughly 25 nmol/L. Levels above about 10 µg/L prompt a full dietary and occupational history. These are investigative triggers rather than thresholds of toxicity.
Should I request blood or urine mercury?
Blood mercury mainly reflects recent organic methylmercury exposure from fish and has a half-life of around 50 to 70 days. Urine mercury reflects inorganic and elemental exposure. The two answer different questions and are not interchangeable.
Is chelation used for high blood mercury from fish?
No. Chelation is reserved for symptomatic inorganic or elemental poisoning. For dietary methylmercury the treatment is to change the fish eaten and re-test after a few months, as the level falls with a half-life of about two months.
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References
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Mercury. Atlanta, GA: US Department of Health and Human Services; 2022.
- Centers for Disease Control and Prevention. Fourth National Report on Human Exposure to Environmental Chemicals. Atlanta, GA: CDC.
- Ye BJ, Kim BG, Jeon MJ, et al. Evaluation of mercury exposure level, clinical diagnosis and treatment for mercury intoxication. Ann Occup Environ Med. 2016;28:5.