SI Units: The International System of Units is a system devised around the convenience of the number ten. It is the worlds most widely used system of measurement in science.
SI Standard units are Kelvin (K)
Celsius = K-273
Kelvin = Celsius+273
Celsius = 5/9 (F – 32)
Fahrenheit = (9/5 x C) + 32
A solution is a homogenous mixture of two or more substances. A solute is a substance that is small part of a solution. A solvent is a substance that constitutes a large portion of a solution. Solubility refers to the solutes ability to dissolve in the solvent.
A dilution is when the solute or substance of interest is combined with an appropriate volume of solvent to achieve a desired concentration. The dilution factor is the resulting total number of unit volumes in which the solute was dissolved.
For example: Dissolving one part solute into 3 parts solvent. Total dilution is 1:4. The dilution factor is 4 because there are four total parts of unit volumes.
(C1)(V1)=(C2)(V2) is used when making fixed volumes of specific concentrations.
Percent solutions refer to parts per hundred. They can either be percent by volume (% (v/v)) or percent by mass (% (m/m)).
Percent by Volume (% (v/v)) = (Volume of solute/Volume of solution) x 100
Percent by Mass (% (m/m)) = (Mass of solute/Mass of solution) x 100
Molarity is a unit of concentration equal to the number of moles of solute in one liter of solution.
Molarity (M) = Moles of solute/Liters of solution
Density is the ratio between the mass and volume of a material.
Density = Mass/Volume
Specificity: The frequency of a negative test when no disease is present.
Specificity = (True negatives/True negatives+False positives) x 100
Sensitivity: The frequency of a positive test when disease is present.
Sensitivity = (True positives/True positives+False negatives) x 100
Calculated plasma osmolality = 2[Na+] + Glucose/18 + BUN/2.8
Osmolar Gap: Difference between the measured and calculated osmolality.
LDL = Total cholesterol – HDL – VLDL
Triglycerides = (Total cholesterol – HDL – LDL) x 5
Precaution: The Friedman formula is only reliable for triglyceride levels less than 400 mg/dL.
Total Bilirubin = Conjugated bilirubin + Unconjugated bilirubin
Conjugated Bilirubin = Total bilirubin – Unconjugated bilirubin
Unconjugated bilirubin = Total bilirubin – Conjugated bilirubin
Creatinine Clearance = Male (1.0), Female (0.85) x (140-age) x (Serum Creatinine) x (Weight/72).
Hematocrit: The percentage of blood that is represented by packed red cells.
Hematocrit (%) = Hemoglobin x 3
MCV: Mean cell volume refers to the average size of the red cell population within the sample.
MCV = (Hematocrit (%) x 10)/RBC (x10^12/L)
MCH: Mean cell hemoglobin refers to the average weight of hemoglobin within the red cell population.
MCH = (Hgb x 10)/RBC (x10^12/L)
MCHC: Mean cell hemoglobin concentration refers to the average concentration of hemoglobin within the red cells constituting the sample.
MCHC: (Hgb x 100)/Hematocrit (%)
Corrected WBC: Nucleated RBCs are counted as white blood cells regardless of which method is utilized. For this reason when a differential is performed and there is presence of NRBCs a corrected WBC must be calculated. The number of NRBCs per 100 leukocytes is recorded during the differential leukocyte count when performing a blood smear examination. This number is then used;
Corrected WBC = (WBC x 100)/(NRBC + 100)