Units of Measurement Ms. Ryan MCATC Medical Math

Systems of Measurement for Medication Three systems used in United States for prescribing, administering, and dispensing medication: Metric: used most often because it provides a more exact measurement Apothecary: occasionally used Household: used by patients taking medication at home

Units of Measurement Weight: heaviness of an item Volume: amount of space occupied by a substance Length: linear measurement of distance from one point to another – Not used to administer medications – Used in other aspects of medical office (measurement of body)

Metric System Basic units – Gram: unit of weight For measuring solids – Liter: unit of volume For measuring liquids – Meter: linear unit For measuring length and distance Units most often used to administer medication: – Milligram (weight) – Gram (weight) – Milliliter (volume) – Cubic centimeter: amount of space occupied by 1 ml – (1 ml = 1 cc) – DO NOT USE CC FOR MEDICATION USE ANYMORE

Review of the Basic Metric Units Length – 100 cm = 1 m – 10 mm = 1 cm – 1,000 mcm = 1 mm Volume – 1,000 ml = 1 L – 1,000 mcl = 1 mL Weight – 1,000 g = 1 kg – 1,000 mg = 1 g – 1,000 mcg = 1 mg You must memorize the abbreviations No periods after metric abbreviations

Household System Less accurate than metric or apothecary Frequently used in United States May be only system patient can – Understand – Safely use to take liquid medication at home (e.g., teaspoon) Volume: only household unit used to administer medication – Drop (gtt) – Teaspoon – Tablespoon – Ounce – Cup – Glass

Apothecary System Older and less accurate than metric system – Gradually being phased out for measurement of medications Developed in England in eighteenth century Units – Weight Grain Dram Ounce Pound – Length Inch Foot Yard Mile – Volume Minim Fluid dram Fluid ounce Pint Quart Gallon