exam 2 Introduction to Clinical Chemistry

What is included in the minimum database

- CBC

- Chemistry

- Urinalysis

What is in a chemistry

- Blood glucose

- Proteins

- Renal Values

- Liver Values

- Electrolytes & Minerals

- Pancreatic Enzymes

- Other (cholesterol & creatine kinase)

What proteins are evaluated in a chemistry?

- Albumin

- Globulin

- TP

What renal values are evaluated in a chemistry?

- Blood urea nitrogen (BUN)

- Creatinine

What liver values are evaluated in a chemistry?

- ALT

- ALP

- AST

- GGT

- Bilirubin (BILI)

What Electrolytes and minerals are evaluated in a chemistry?

- Na

- K

- Cl

- Ca

- Phosphorus

- Mg

- HCO3-

What pancreatic enzymes are evaluated in a chemistry?

- Amylase

- Lipase

What does Total T4 test for

Thyroid function

What does SDMA test for

Kidney function

What does bile acids test for

Liver function

What does C-reactive protein test for

Inflammation

What does progesterone test for

Reproduction and cycle tracking

What does fructosamine test for

Diabetic monitoring

What does urine protein:creatine ratio test for

Renal disease

What does phenobarbitol test for

Drug monitoring

Chem 17

Advanced, includes normal tests + amylase and lipase

Chem 15

Basic full chemistry panel

Chem 10

Abbreviated chem panel, good for young pre-op patients

NSAID 6

Liver and renal values for monitoring NSAIDs

Lytes 4

Tests for Na, K, Cl, Na/K

Chemistry panels

- Use serum, plasma, or whole blood

- Do not evaluate blood cells

- Organ function

What tube do we use for plasma chemistry collection

Lithium heparin (green top)

What tube do we use for serum chemistry collection

Non additive (red top) or serum separator (tiger top)

Preanalytical testing

Patient prep (fasting), tube filling, specimen handling & storage

Analytical testing

Analyzer function and performance aka the machine working properly

Postanalytical testing

Data logging & reporting

What phase of testing that impacts results is least error prone

Analytical

How does EDTA contamination influence results

- Falsely lower Calcium

- Falsely higher potassium

- Interference w/ specialized tests

What can cause inaccurate results

- Hemolysis

- Lipemia

- Icterus

- Medications

- Poor sample handling

What causes in vitro hemolysis

- Blood is drawn into a moist tube

- Vigorous mixing of sample

- Forcefully pushing sample through needle

- Excess alcohol on fur

- Sample is lipemic

How does intracellular fluid diluting the sample as a result of hemolysis effect results

Lowers PCV, HCT, & RBC count

Hemolysis can cause false elevations to what values

- K

- Phosphorus

- Enzymes

- MCH, MCHC

- Ghost RBCs counted as PLT

What sample processing does hemolysis interfere with

- Increased bilirubin

- Lipase

- Refractometer line blurred

How to avoid hemolysis

- Use dry syringe

- Remove the needle from the syringe before transferring

- Allow alcohol on fur to dry before venipuncture

- Centrifuge at appropriate speed and time

How does icterus effect lab results

- No effect on CBC measurements

- Low creatinine

- Low TP

- Chemistry interference due to spectral properties and reacts chemically w/ reagents

Lipemia (Lactescence)

- Elevated triglycerides in blood sample

- Light scattering effect

- Volume displacement effect (mostly affects electrolytes)

How to avoid lipemia

Collect blood on a fasted animal

In what diseases is lipemia unavoidable

- Diabetes mellitus

- Pancreatitis

- Hepatic lipidosis (horses)

- Neoplasia (Thoroughbreds)

What should you check for before sending out a sample

- Hemolysis

- Lipemia

- Icterus

Types of assays

- Photometric

- Electrochemical

Photometric Assay measures what

Color change

Electrochemical Assay measures what

Electrical current change

What do spectrophotometers do

Measures the amount of light transmitted through a solution

Types of photometric assays

- End Point

- Kinetic

What assay provides a single measurement after a set time

End point

What assay measures reaction rates by taking several measurements over time

Kinetic

What assay is common for measuring blood enzymes or when the reagent is an enzyme

Kinetic

Ion-selective Electrodes (ISE)

Measures ions in a sample by measuring electrode and individual ion interactions

Electrochemical Analyzers

Measures ions through electrodes incorporated into biosensor reagent strips or cartridges

Liquid reagents in common analyzers

- Used in a rotor system

- Less expensive

- Some don't allow for running a single test

Dry reagents in common analyzers

- Slides or cartridges

- Impregnated w/ reagent

- More costly but fast, less hazard or storage concerns

Reference ranges

"Normal Values" based on results from samples run on the specific machines in a lab