Electrolytes

This section will cover:

• Electrolytes’ roles in the body
• How to measure and interpret electrolyte levels
• How to connect laboratory results to clinical diagnosis

Biochemical Theory and Pathways

• Electrolytes: Ions in solution, crucial for fluid balance, nerve/muscle function
• Key Electrolytes
  • $Na^+$, $K^+$, $Cl^-$, $HCO_3^-$, $Ca^{2+}$, $Mg^{2+}$, $P$, $Fe$
• Regulation
  • Hormones: Aldosterone, ADH, PTH, Vitamin D
  • Organs: Kidneys, parathyroid glands
• Transport Mechanisms
  • Ion channels, pumps, binding proteins

Laboratory Test Procedures

• Common Methods
  • Ion Selective Electrodes (ISE)
  • Spectrophotometry
  • Blood Gas Analysis
• Key Analytes Measured
  • Electrolyte concentrations in serum, plasma, or whole blood
  • Total Iron-Binding Capacity (TIBC)
• Important Considerations:
  • Proper specimen collection and handling
  • Reagent and calibration controls

Calculations

• Osmolality
  • Formula: $2[Na^+] + \left( \frac {[Glucose (mg/dL)]} {18} \right) + \left( \frac {[BUN (mg/dL)]} {2.8} \right)$
  • Assesses hydration, presence of toxins
• Anion Gap
  • Formula: ($Na^+$ + $K^+$) - ($Cl^-$ + $HCO_3^-$)
  • Identifies causes of metabolic acidosis

Test Result Interpretation

• Relate to the patient’s specific information
• Consider reference ranges
• Look at patterns and trends
• What other conditions are indicated or ruled out by these patterns?

Disease State Correlation

• Key Diseases
  • Hyponatremia, hypernatremia
  • Hypokalemia, hyperkalemia
  • Hypocalcemia, hypercalcemia
  • Hypomagnesemia, hypermagnesemia
  • Hypophosphatemia, hyperphosphatemia
  • Iron Deficiency Anemia, hemochromatosis
  • List may also include cardiac, renal, neurological, etc