what is the conversion factor between IU and mIU?

HCG hormone is measured in international units (IU). I have also come accross measurements in mIU. Is there a conversion factor that applies, or are they the same unit? I checked wikipedia, and called several pharmacists . No one knows.

Thanks in advance.


It’s probably milliIU or 1/1000 of an IU.

Without any knowledge about HCG, I’d assume that the lower-case “m” is an SI prefix. One mIU would then be 0.001 IU.

One mIU is indeed 1/1000 of an IU.

However, conventionally HCG levels are given in terms of concentration e.g international units per litre: IU/L. Slightly confusingly, both IU/L and mIU/mL are in common use. Since one mL is 1/1000 of a litre, the two factors cancel, so 1 IU/L = 1 mIU/mL.