Basic Principles and Practices

Which component of blood contains fibrinogen?

Plasma

Which component of blood does NOT contain fibrinogen?

Serum

Easy short cut to remember which has fibrinogen?

Plasma —> Fiber (Aka Party Finder)
Serum —> No Fibrinogen (Aka SF got clogging issues : ()

When would you use a timed urine sample (24 hours)?

Usually pregnancy

What is red tops for?

Collecting serum

How many minutes are required for a red-top to sit?

20 minutes

What is Gold top used for?

When you want to create a physical barrier between serum and cells after centrifugation

• Can be used for most chemistry analysis

What are the 2 analytes a gray top can contain?

• Sodium fluoride and potassium oxalate

• Sodium iodoacetate

What is the purpose of gray top?

To stabilize glucose in plasma

What is the green top contain?

Either

• Sodium

• Ammonium

• Lithium salt of heparin

What is the importance of heparin in a green top?

Heparin inhibits thrombin, so blood does not clot

What is the lavender top?

EDTA —> prevents coagulation

Why can’t you use lavender top for chemistry?

Because they interfere with the test by chelating minerals and produces:

• Falsely low iron, Ca and MG results

• Falsely high K results

What are the 2 principle spectrophotometry is based on?

1) Substances absorb light at unique wavelength

2) The amount of light absorbed is proportional to the amount of substance that is present

What is the equation for Beer’s law?

A = ebc

When do you need to transport a specimen on ice?

When it contains ammonia or blood gas

What is the TLDR of Beer’s law?

Concentration is DIRECTLY proportional to the amount of light absorbed

• AKA higher concentration of stuff = higher absorbance

What is the usage of colorimetric?

Directly measures the intensity of color in a solution (proportional to the concentration of the analyte)

What is an example of colorimetric test?

Urine dipsticks

What is the usage of Endpoint?

Measure the final product of a chemical reaction after it gone to completion

• Allows for interfering reaction to be accounted for

What is an example of Endpoint?

Measuring blood glucose using hexokinase method

What is the usage of Initial rate?

Measure the rate of reaction at its beginning is proportional to the concentration of the analyte

• Aka higher the initial analyte, the FASTER the reaction

What is an example of initial rate?

BUN measurement

What is the principle of turbidity?

Measuring the decrease in intensity of incident light caused by scattering, absorbance and reflectance

What is the angle turbidity is measured at?

180 degree

What component does turbidity measure?

Proteins and immunoglobulins

What is the proportional concentration of Turbidity?

The amount of light scattered is directly proportional to concentration of insoluble particles

What is the angle nephelometry measured at?

90 degree

What is the difference between nephelometry verses turbidity?

Nephelometry can measure small particles aka more sensitive while turbidity is more generalized

What are some sample test of turbidimetry?

• C-reactive protein

• Urine

• CSF protein

• Prealbumin testing

What are some sample test of nephelometry?

Microalbumin and ceruloplasmin

What is the key of flow cytometry?

Fluorescence is absorbed at 1 wavelength and emission at longer wavelength

How does flow cytometry work?

Cells move 1 at a time through a laser, and detection of size and granularity of the WBC is determined

What is chromatography?

When molecules in a mixture is applied onto the surface or into a solid and a fluid stationary phase is separated from each other via mobile phase

What are some test that are done with Point-of-Care?

• Glucose

• Electrolyte

• Coagulation

• and ABG testing

What is the difference between spectrophotometery and spectrophotometer?

-metry —> Measures intensity of light at a SELECTED wavelength

-meter —> measure the amount of light absorbed by a sample at different wavelength

What is the wavelength of ultraviolet light?

190-390 nm

What is the wavelength of X ray and gamma rays?

<190 nm

What is the wavelength of visible light?

390-750 nm

What is the wavelength of infrared light?

>750 nm

What is important about complementary color?

If a substance appears as a certain color, then it would be absorbing wavelength from its complementary color.

Ex) if the sample is visually orange, then the sample would absorb blue light

What is the wavelength of violet?

440 nm

What is the wavelength of blue?

500

What is the wave length of Green?

580

What is the wavelength of yellow?

600

What is the wavelength of orange?

620

What is the wavelength of red?

750

What is the assumption of Beer’s Law?

That the light is monochromatic, a singular wavelength with no stray lights

What is the equation of Beer’s law?

Conc(u) = [Abs(u) * Con(s)] / Abs (s)

A glucose standard of 200mg/Dl reads 0.4A and a patient’s sample reads 1.0A. Calculate the glucose concentration of the patient sample in mg/dL?

What is the principle of biochromatic analysis?

Split the light beam into 2 and select a different wavelength for each beam

• One is the desired peak of the analyte

• Second is not absorbed by the analyte

• Second wavelength is subtracted from first to determine the concentration of analyte

Why is biochromatic analysis important?

Because hemoglobin from hemolysis absorbs light at the same wavelength to measure bilirubin

• so we use bichromatic analysis to determine the difference between the two

What can you use as the second wavelength in bichromatic analysis?

A serum blank

When would you use serum blanks for bichromatic analysis?

Lipemic samples, hemolyzed or iceteric

What is spectrophotometry?

Measurement of intensity of light at a selected wavelength

What is the adsorption peak for NADH?

340 nm