Some medical tests report results in nanograms per milliliter per hour.

• A nanogram is one-billionth of a gram. A gram is about 1/30 of an ounce.
• A milliliter measures fluid volume equal to 1/1000 liter. A liter is a little bigger than a quart.
• An hour is the time period that the amount of nanograms per milliliter is measured for.