Procedures

Reliable lab testing of electrolytes is crucial for accurate clinical diagnosis and management

Analytical Principles

Tests measure electrolyte concentrations in serum, plasma, or whole blood using various methods:
- Ion Selective Electrodes (ISEs): Measure the activity of ions
  - Direct ISE: Uses undiluted sample
  - Indirect ISE: Requires sample dilution
- Spectrophotometry: Measures light absorbance
Key Electrolytes
- Sodium, Potassium, Chloride, Total Carbon Dioxide
- Calcium, Magnesium, Phosphorus, Iron, TIBC

Patient Preparation
- Fasting: For certain analytes
- Medications: Review medication list
- Hydration Status: Essential to note
Specimen Collection
- Correct specimen type (serum, plasma, whole blood)
- Correct tube type
- Adhere to recommended order of draw for multiple tubes
- Minimize tourniquet time
- Avoid hemolysis
Specimen Handling and Processing
- Process promptly
- Use correct centrifuge settings
- Adhere to strict storage temperatures
Analytical Considerations
- Assure reagent quality
- Calibrate instruments correctly
- Run Quality Control regularly

Unexpected Results
- Check for pre-analytical issues
- Check analytical steps
- Consider interfering substances
- Evaluate QC data
- Repeat testing if necessary
Out-of-Control Quality Control
- Check integrity of QC materials
- Prepare fresh QC materials
- Recalibrate instrument
- Review reagent quality

Endogenous
- Lipemia (turbidity)
- Bilirubin (absorbance)
- Hemoglobin (releases ions)
- Urea (alters enzyme activity)
Exogenous
- Medications
- Contamination