Jarreau Clinical Chemistry - Elecrolyes Flashcards
Sodium is the major ________ of extracellular fluid.
Cation
The major function of sodium is what?
Maintain osmotic pressure.
________% of sodium is absorbed in the kidney tubules.
85
Reference range of sodium.
135 - 145 mmol/L
What diseases are associated with hyponatremia?
(1) Diabetic acidosis
(2) Diarrhea
(3) Addison’s disease
(4) Renal tubular disease
Hypernatremia is associated with what disease states?
(1) Cushing’s syndrome
(2) Dehydration
(3) Hyperaldosteronism
(4) Insulin treatment of uncontrolled diabetes
What testing method is most commonly used for sodium?
Ion-selective electrode.
________ electrode is selective for sodium.
Glass
Describe direct reading in electrolyte testing.
Sample not diluted.
Describe indirect reading in electrolyte testing.
Sample diluted.
Pseudohyponatremia is present in increased ________ or ________.
triglycerides; protein.
Potassium is the major ________ of intracellular fluid.
cation
Potassium reference range.
3.5 - 5.0 mmol/L
Potassium is ________ times higher in cells than in plasma.
23
For potassium testing, separate serum from cells to prevent what?
K from shifting to serum.
Falsely increased potassium may be caused by:
(1) Hemolysis
(2) EDTA Contamination
(3) Prolonged tourniquet application
(4) Excessive heel or finger squeezing
Plasma and whole blood potassium is ________ lower than serum potassium.
0.1 - 0.7
Hypokalemia and hyperkalemia may cause:
(1) Heart arrhythmias
(2) Neuromuscular symptoms (weakness, paralysis)
Hypokalemia can be caused by:
(1) Insulin injections
(2) Alkalosis
(3) GI loss
(4) Hyperaldosteronism
(5) Cushing’s syndrome
Hyperkalemia can be caused by:
(1) Diabetic acidosis (metabolic)
(2) Intravascular hemolysis
(3) Severe burns
(4) Renal failure
(5) Addison’s disease
What testing method is most commonly used for potassium?
Ion-selective electrode
________ is selective for potassium.
Valinomycin membrane
Chloride is the major ________ of extracellular fluid.
anion
Describe the function of chloride.
(1) Maintains hydration
(2) Osmotic pressure regulation
(3) Normal anion-cation balance
Chloride reference range.
98-106 mmol/L
Chloride generally follows ________ so increase and decrease in same conditions.
Sodium
Hypochloremia is caused by:
(1) Diabetic acidosis (excessive acid production)
(2) Chronic pyelonephritis
(3) Prolonged vomiting
(4) Aldosterone deficiency
Hyperchloremia is caused by:
(1) Prolonged diarrhea (excessive bicarbonate loss)
(2) Renal tubular acidosis
(3) Adrenocortical hyperfunction
What is the most common method for chloride testing?
Ion-selective electrode.
What type of electrode is used for chloride testing?
AgCl (silver chloride) reference electrode.
Describe coulometric titration for chloride testing.
Generation of Ag ions which combine with Cl ions.
Describe colorimetry using Hg(SCN)2 for chloride testing.
Automated thiocyanate method. Forms reddish color with peak at 480 nm.
Sweat chloride is elevated in what disease state?
Cystic fibrosis.
What is the testing method used in sweat chloride testing?
Iontophoresis
In sweat chloride testing, what drug is used to induce sweating?
Pilocarpine
In sweat chloride testing, what chloride result would be indicative of cystic fibrosis?
> 60 mmol/L
Describe the function of the chloride shift.
A buffering system of the blood (acid-base balance).
In chloride shift, ________ pulled out of erythrocytes and ________ moves into erythrocytes, resulting in decreased serum ________.
bicarbonate; chloride; chloride
Reference range of potassium.
3.5 - 5.0 mmol/L
Potassium is ________ times higher in cells than in plasma.
23
How should samples collected for potassium testing be handled?
Separate from cells quickly to prevent K from shifting to serum.
Total CO2 is calculated by the addition of what three analyses?
Carbon dioxide, bicarbonate, carbonic acid.
CO2 generally reflects what other analytes concentration?
Bicarbonate
What three testing methods are used in CO2 testing?
(1) Volumetric
(2) Manometric
(3) Colorimetric
The anion gap is a calculation that reflects differences between:
Unmeasured cations and anions.
Anion gap can be used as ________ for measuring all electrolytes.
analytical QC
If there is an abnormal anion gap for multiple patients, what should the technologist suspect?
Problems with electrolyte measurements.
List the three unmeasured cations.
(1) Potassium
(2) Calcium
(3) Magnesium
List the three unmeasured anions.
(1) Albumin
(2) Sulfate
(3) Phosphate
What is the calculation of anion gap? (with K)
[(Na)+(K)] - [(Cl)+(HCO3)]
What is the calculation of anion gap? (without K)
(Na) - [(Cl)+(HCO3)]
What is the reference range for the anion gap if you include potassium in the calculation?
10-20 mmol/L
What is the reference range for the anion gap if you do not include potassium in the calculation?
7 - 16 mmol/L
For an increased anion gap, what would cause an increased concentration of unmeasured anions?
(1) Alcohols & Salicylates
(2) Ketones
(3) Lactic Acid
For an increased anion gap, what would cause an increased concentration of unmeasured cations?
(1) Low serum Magnesium
(2) Low serum Calcium
For a decreased anion gap, what would cause a decrease concentration of unmeasured anions?
Albumin loss.
For a decreased anion gap, what would cause an increase concentration of unmeasured cations?
(1) High serum Magnesium
(2) High serum Calcium
(3) Lithium therapy
Conditions causing an increased unmeasured anions.
S alicylate Intoxication
L actic Acidosis
U measured ions
M ethanol
P olyethylene Glycol
E thanol
D iabetic Ketoacidosis
Define osmolality.
Measure of total concentration (number) of dissolved particles in a solution (molecular weight, size, density, or type of particle does not matter).
Osmolality can be measured directly - describe the two practical testing methods.
(1) Freezing point depression
(2) Vapor pressure depression
Define the equation to calculate osmolality.
2Na + (Glucose/18) + (BUN/2.8)
When measured osmolality is >10 higher than calculated osmolality, this indicates what?
Presence of exogenous unmeasured anions (e.g., methanol, ethanol, ketone bodies)
Urine osmolality is best used to evaluate what disease state?
Renal tubular function
Urine to serum osmolality ratio is best used to determine…
The kidney concentrates to glomerular filter.
What is the function of magnesium?
Calcium channel blocking agent (affects heart).
Magnesium is elevated in what disease state?
Renal failure.
Magnesium is decreased in what disease state?
(1) Cardiac disorders
(2) Diabetes mellitus
(3) Diuretics, alcohol or other drugs
(4) Tetany
List the testing methodologies used for magnesium testing.
(1) Atomic absorption
(2) Colorimetric methods
In cases of Tetany, suspect…
Decreased calcium FIRST, then decreased magnesium or potassium.
What is the function of calcium?
Combines with phosphate in bone and teeth.
Calcium plasma distribution: ________ protein bound, ________ ionized (active), and ________ complexed.
45%; 45%; 10%
What are the three hormones that control calcium.
(1) PTH
(2) Calcitonin
(3) Vitamin D
PTH (increases/decreases) calcium.
Increases.
Calcitonin (increases/decreases) calcium by:
Decreases; inhibits bone reabsorption.
Vitamin D (increases/decreases) calcium by:
Increases; increases absorption in the intestines.
What are the symptoms of hypercalemia.
Muscle weakness and disorientation.
What conditions may cause hypercalcemia?
(1) Hyperparathyroidism
(2) cancer with bone metastasis
(3) Multiple myeloma
(4) Renal failure
What conditions may cause hypocalcemia?
(1) Hypoparathyroidism
(2) Decreased serum albumin
(3) Decreased vitamin D
What are the testing methodologies for calcium?
(1) Atomic absorption spectroscopy - reference method
(2) Colorimetric method - most common
