microgram
Meaning of microgram: A microgram is a metric unit of mass equal to one millionth of a gram, commonly used to measure very small medication doses.
Definition of microgram
A microgram is a unit of mass in the metric system equal to one millionth of a gram, or one thousandth of a milligram. It is commonly abbreviated as mcg in clinical practice, since the symbol for micro can be more easily misread, particularly in handwritten orders.
Microgram-scale measurements are used for substances that are active in very small amounts, including certain hormones, some potent medications, and trace nutrients such as particular vitamins. Because the microgram is a much smaller unit than the milligram, a dosing error that confuses the two units can result in a substantial and potentially serious difference in the amount given.
Careful attention to units is especially important whenever a medication is dosed in micrograms, given how small a quantity this represents compared with the more commonly used milligram.
How microgram is built
- micro- Prefix · Greek small
- -gram Suffix · Greek the record or image produced
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
Also known as
Used in a sentence
The medication order specified a dose measured in micrograms rather than milligrams.
Good to know
Confusing microgram (mcg) with milligram (mg) represents a one-thousand-fold difference in quantity, which is why the full unit is often written out to avoid misreading abbreviations.
Word origin
Where “microgram” comes from
Formed from micro- (Greek mikros, meaning "small") and gram, from Greek gramma, a term for a small weight or unit of writing.