Electrolytes and Osmolality

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  1. What is the term for the properties of a solution that are influenced by the number of molecules in solution, but not their individual composition?
    Colligative properties
  2. What are the 4 types of colligative properties?
    • Boiling point
    • Freezing point
    • Osmotic pressure
    • Vapor pressure
  3. What is the term is the measure of the number of dissolved particles in solution expressed as osmoles per kilogram of water?
  4. What is the reference range of Serum Osmolality?
    275-295 mOsm/kg
  5. How is osmolality regulated?
    Regulated by the hypothalamus thhrough the sensation of thirst and the signaling to secrete antidiuretic hormone (ADH)
  6. What happens when osmolality of the blood increases?
    • Consuming more water will decrease the osmolality
    • Posterior pituitary secretion of ADH will cause renal reabsorption of water and decrease the osmolality
  7. What is the term for the method used to measure all particles (molecules and ions) in solution?
  8. What are the 2 formulas used to calculate estimated osmolality?
    Image UploadImage Upload
  9. What represents the difference between the measured and calculated osmolality and what is the reference range?
    • Osmolal gap
    • <15
  10. What test is useful in assessing electrolyte disorders and acid-base status?
    Serum and Urine Osmolality
  11. Name the major molecules measured by serum osmolality
    • Sodium
    • Chloride
    • Glucose
    • Urea
  12. What is the term for charged ions found in intracellular fluid, extracellular fluid, and interstitial fluid?
  13. What is the term for positively charged ions?
  14. What is the term for negatively charged ions?
  15. Name the major cations in the body
    • Na
    • K
    • Ca
    • Mg
  16. Name the major anions in the body
    • Cl
    • Bicarbonate
    • Phosphate
    • Sulfate
    • Organic acids
    • Protein
  17. What is the major cation of extracellular fluid?
  18. What is the reference range of sodium?
    136-145 mmol/L
  19. When is sodium excreted in the urine?
    When the renal threshold for serum sodium exceeds 110-130 mmol/L
  20. When does hyponatremia occur?
    Sodium <135 mmol/L
  21. What clinical conditions occur with hyponatremia?
    • Depletional hyponatremia - diuretics, hypoaldosteronism (Addison disease), diarrhea, vomiting, severe burns, or trauma
    • Dilutional hyponatremia - overhydration, syndrome of inappropriate antidiuretic hormone (SIADH), congestive heart failure, cirrhosis, and nephrotic syndrome
  22. What clinical conditions cause hypernatremia?
    • Diarrhea
    • Excessive sweating
    • Diabetes insipidus
    • Acute ingestion
    • Hyperaldosterism
    • Infusion of hypertronic solutions during dialysis
  23. When does hypernatremia occur?
    When sodium is >150 mmol/L
  24. Name the major intracellular cation
  25. What is the reference range of potassium?
    3.4-5.0 mmol/L
  26. When does hypokalemia occur?
    Serum potassium <3.0 mmol/L
  27. What causes hypokalemia?
    • Decreased dietary intake
    • Hyperaldosteronism
    • Diuretics
    • Vomiting
    • Diarrhea
    • Laxative abuse
    • Excess insulin
  28. When does hyperkalemia occur?
    Serum potassium >5.0
  29. What causes hyperkalemia?
    • Increased intake
    • Renal failure
    • Hypoaldosteronism
    • Metabolic acidosis
    • Increased RBC lysis
    • Leukemia
    • Chemotherapy
  30. Name the major anion extracellular fluid
  31. What is the reference range of chloride?
    98-107 mmol/L
  32. When does hypochloremia occur?
    Chloride <98 mmol/L
  33. What causes hypochoremia?
    • Excessive vomiting
    • Diuretics
    • Burns
    • Aldosterone deficiency
  34. When does hyperchloremia occur?
    Chloride >107 mmol/L
  35. Name the 2nd largest anion fraction of extracellular fluid
    Bicarbonate (HCO3-)
  36. What is the reference range of bicarbonate?
    22-29 mmol/L
  37. What is the clinical significance associated decreased ctCO2?
    • Metabolic acidosis
    • Diabetic ketoacidosis
    • Salicylate toxicity
  38. What is the clinical significance associated increased ctCO2?
    • Metabolic alkalosis
    • Emphysema
    • Severe vomiting
  39. What is the term for the mathematical formula used to demonstrate electroneutrality of body fluids?
    Anion gap
  40. What does the anion gap represent?
    Represents the difference between cations and anions that are not actually measured analytically when serum electrolytes are quantified
  41. What is the calculation used to calculate the anion gap?
    • Na - (Cl + HCO3-) = anion gap
    • Reference range 7-16 mmol/L

    • (Na + K) - (Cl +HCO3-) = anion gap
    • Reference range 10-20 mmol/L
  42. What causes an increased anion gap?
    • Uremia
    • Lactic acidosis
    • Ketoacidosis
    • Hypernatremia
    • Ingestion of methanol, ethylene glycol, or salicylate
  43. What causes a decreased anion gap?
    • Hypoalbuminemia
    • Hypercalcemia
Card Set:
Electrolytes and Osmolality
2013-05-06 02:01:56
Osmolality Electrolytes

Osmolality and Electrolytes
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