Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content + INTRODUCTION Print Section ++ ++ The International System of Units (abbreviated SI from the French phrase, Système International d’Unités), or SI, is the standard system of measurement. ++Table Graphic Jump LocationMetric PrefixesView Table|Favorite Table|Download (.pdf) Metric Prefixes Prefix Symbol 10n exa E 1018 peta P 1015 tera T 1012 giga G 109 mega M 106 kilo k 103 hecto h 102 deca da 101 100 deci d 10-1 centi c 10-2 milli m 10-3 micro μ 10-6 nano n 10-9 pico p 10-12 femto f 10-15 atto a 10-18 ++Table Graphic Jump LocationLengthView Table|Favorite Table|Download (.pdf) Length Symbol Known Quantity Multiply Metric Symbol Known Quantity in inches 2.54 cm centimeters ft feet 30 cm centimeters ft feet 0.3 m meters yd yards 0.9 m meters — miles 1.6 km kilometers ++Table Graphic Jump LocationAreaView Table|Favorite Table|Download (.pdf) Area Symbol Known Quantity Multiply Metric Symbol Known Quantity sq in square inches 6.5 cm2 square centimeters sq ft square feet 0.09 m2 square meters sq yd square yard 0.8 m2 square meters — square miles 2.6 km2 square kilometers ++Table Graphic Jump LocationVolumeView Table|Favorite Table|Download (.pdf) Volume Symbol Known Quantity Multiply Metric Symbol Known Quantity tsp teaspoons 5 mL milliliters tbssp tablespoons 15 mL milliliters fl oz fluid ounces 30 mL milliliters c cups 0.24 L liters pt US pints 0.47 L liters qt US quarts 0.95 L liters gal US gallons 3.8 L liters cu ft cubic feet 0.03 m3 cubic meters cu yd cubic yard 0.76 m3 cubic meters ++Table Graphic Jump LocationMassView Table|Favorite Table|Download (.pdf) Mass Symbol Known Quantity Multiply Metric Symbol Known Quantity oz ounces 28 g grams lb pounds 0.45 kg kilograms ++Table Graphic Jump LocationEnergyaView Table|Favorite Table|Download (.pdf) Energya Symbol Known Quantity Multiply Metric Symbol Known Quantity Kcal kilocalories 4.184 kJ kilojoules aThe kilocalorie (kcal) is still most commonly used to express the energy content of macronutrients, energy expenditure, and energy requirements, although kilojoules (kJ) is the SI unit. ++Table Graphic Jump LocationPressure or Mechanical StressView Table|Favorite Table|Download (.pdf) Pressure or Mechanical Stress Symbol Known Quantity Multiply Metric Symbol Known Quantity cm H2Oa centimeter of water (4°C) 0.01 Pa Pascal mm Hg millimeter of mercury (0°C) 7.5006 kPa kilopascal mm Hg millimeter of mercury (0°C) 1.36 cm H2O centimeter of water (4°C) aIn clinical practice arterial blood pressure is still measured in mm Hg, cerebrospinal fluid pressure in mm H2O, and blood gases (Pco2 and Po2) in mm Hg. ++Table Graphic Jump LocationTemperatureaView Table|Favorite Table|Download (.pdf) Temperaturea Symbol Known Quantity Calculation Metric Symbol Known Quantity °F degree Fahrenheit ([°F] – 32)/1.8 °C degree Celsius °C degree Celsius [°C] + 273.15 K Kelvin °F degree Fahrenheit ([°F] +459.67) × 5/9 K Kelvin aTemperature is normally expressed in degrees Celsius (°C), although the SI base unit for temperature is the Kelvin. ++Table Graphic Jump LocationCommon LaboratoriesView Table|Favorite Table|Download (.pdf) Common Laboratories Analyte Specimen Conventional Unit (Reference Range) Conversion Factor (Multiply) SI Unit (Reference Range) Albumin Serum g/dL (3.5-5.0) 10 g/L (35-50) Alkaline Phosphatase Serum U/L (30-120) 0.0167 μkat/L (0.5-2.0) Alanine aminotransferase (ALT) Serum U/L (10-40) 0.0167 μkat/L (0.17-0.68) Aspartate aminotransferase (AST) Serum U/L (10-30) 0.0167 μkat/L (0.17-0.51) Bicarbonate Serum mEq/L (21-28) 1 mmol/L (21-28) Bilirubin, total Serum mg/dL (0.3-1.2) 17.104 μmol/L (5.0-21.0) Bilirubin, direct Serum mg/dL (0.1-0.3) 17.104 μmol/L (1.7-5.1) Blood urea nitrogen (BUN) Serum mg/dL (8-23) 0.357 mmol/L (2.9-8.2) Carbon dioxide Pco2 Arterial blood mmHg (35-45) 0.133 kPa (4.7-5.9) Oxygen, Po2 Arterial blood mmHg (80-100) 0.133 kPa (11-13) Calcium, total Serum mg/dL (8.2-10.2) 0.25 mmol/L (2.05-2.55) Chloride Serum, plasma mEq/L (96-106) 1 mmol/L (96-106) Cholesterol (total) Serum, plasma mg/dL (< 200) 0.0259 mmol/L (< 5.18) Cortisol Serum, plasma μg/dL (5-25) 27.588 nmol/L (140-690) Creatinine Serum, plasma mg/dL (0.6-1.2) 88.4 μmol/L (53-106) Glutaminyl-transferase (GGT) Serum U/L (2-30) 0.0167 μkat/L (0.03-0.51) Glucose Serum mg/dL (70-110) 0.0555 mmol/L (3.9-6.1) Lactate Plasma mg/dL (5.0-15) 0.111 mmol/L (0.6-1.7) Lactate dehydrogenase (LDH) Serum U/L (100-200) 0.0167 μkat/L (1.7-3.4) Magnesium Serum mEq/L (1.3-2.1) 0.5 mmol/L (0.65-1.05) Phosphorus (inorganic) Serum mg/dL (2.3-4.7) 0.323 mmol/L (0.74-1.52) Potassium Serum mEq/L (3.5-5.0) 1 mmol/L (3.5-5.0) Protein (total) Serum g/dL (6.0-8.0) 10 g/L (60-80) Sodium Serum mEq/L (136-142) 1 mmol/L (136-142) Uric acid Serum mg/dL (4.0-8.0) 59.485 μmol/L (240-480)