Electrolytes Flashcards

1
Q

The major cation of extracellular fluid is…

A

Sodium.

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2
Q

___% of sodium is reabsorbed in the kidney tubules.

A

85.

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3
Q

Reference range of sodium.

A

135 - 145 mmol/L.

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4
Q

Conditions associated with decreased sodium levels (hyponatremia).

A

(1) Diabetic acidosis; (2) Diarrhea; (3) Addison’s Disease; (4) Renal tubular disease.

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5
Q

Conditions associated with increased sodium levels (hypernatremia).

A

(1) Cushing’s syndrome; (2) Dehydration; (3) Hyperaldosteronism (increased renal reabsorption); (4) Insulin treatment of uncontrolled diabetes.

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6
Q

Method used for sodium measurement.

A

Ion-selective electrode (ISE).

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7
Q

A direct ISE reading of sodium uses a diluted or undiluted sample?

A

Undiluted.

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8
Q

A indirect ISE reading of sodium uses a diluted or undiluted sample?

A

Diluted.

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9
Q

Pseudohyponatremia is defined and caused by…

A

Pseudohyponatremia an a false decrease of sodium levels that is caused by high levels of triglycerides or protein.

↑↑ protein/triglycerides; ↓ sodium.

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10
Q

The major cation of intracellular fluid is…

A

Potassium.

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11
Q

Reference range of potassium.

A

3.5 - 4.0 mmol/L.

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12
Q

What preanalytical factors may cause a false increase in potassium (pseudohyperkalemia)?

A

(1) Hemolysis; (2) EDTA contamination.

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13
Q

Hypo- or hyperkalemia may cause what conditions?

A

Heart arrhythmias and/or neuromuscular symptoms.

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14
Q

Hypokalemia conditions include…

A

(1) Insulin injections; (2) alkalosis; (3) GI losses (vomiting or diarrhea); (4) Hyperaldosteronism; (5) Cushing’s syndrome.

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15
Q

Hyperkalemia conditions include…

A

(1) Diabetic acidosis (metabolic); (2) Intravascular hemolysis; (3) Severe burns; (4) Renal failure; (5) Addison’s disease.

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16
Q

Testing method for potassium…

A

Ion-selective electrode.

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17
Q

Major anion of extracellular fluid is…

A

Chloride.

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18
Q

The function of chloride is…

A

Maintains hydration, osmotic pressure, and the normal anion-cation balance.

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19
Q

Reference range of chloride.

A

98 - 106 mmol/L.

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20
Q

Chloride levels generally trend the same direction as ___.

A

Sodium.

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21
Q

Hypochloremia conditions include…

A

(1) Diabetic acidosis (excessive acid production); (2) Chronic pyelonephritis; (3) Prolonged vomiting; (4) Aldosterone deficiency.

22
Q

Hyperchloremia conditions include…

A

(1) Prolonged diarrhea (excess bicarbonate loss); (2) Renal tubular acidosis; (3) Adrenocortical hyperfunction.

23
Q

Testing method for chloride is…

A

Ion-selective electrode.

24
Q

Sweat chloride testing is elevated in what condition?

A

Cystic fibrosis; >60 mmol/L.

25
Q

Describe the anion gap.

A

Calculation that reflects that differences between unmeasured cations and anions; used as analytical QC for measuring all electrolytes.

If abnormal gaps for multiple patients, suspect problem with electrolyte measurements.

26
Q

What are the major unmeasured cations for the anion gap calculation?

A

Calcium, magnesium, and potassium.

27
Q

What are the major unmeasured anions of the anion gap calculation?

A

Albumin, sulfate, and phosphate.

28
Q

What is the calculation of the anion gap WITH potassium?

A

[(Na)+(K)]-[(Cl)-(HCO3)]

29
Q

What is the calculation of the anion gap WITHOUT potassium?

A

(Na) - (Cl) + (HCO3)

30
Q

Reference range of anion gap (with K).

A

10-20 mmol/L.

31
Q

Reference range of anion gap (without K).

A

7-16 mmol/L.

32
Q

An increased anion gap is indicative of an increased concentration of what three unmeasured anions?

A

(1) Ethanol; (2) Ketones; (3) Lactic acid.

33
Q

A increased anion gap is indicative of an decreased concentration of what two unmeasured cations?

A

Low serum Mg and Ca.

34
Q

A decreased anion gap is indicative of a decreased concentration of what unmeasured anion?

A

Albumin.

35
Q

A decreased anion gap is indicative of an increased concentration of what three unmeasured cations?

A

Mg, Ca, and Lithium therapy.

36
Q

Define osmolality.

A

The measure of total concentration of dissolved particles in a solution.

37
Q

Osmolality can be measured directly using what two testing methods?

A

Freezing point depression and vapor pressure depression.

38
Q

What is the equation to determine calculated osmolality?

A

2Na + (Glucose/18) + (BUN/2.8)

39
Q

A measured osmolality is 10x higher than calculated osmolality indicates the presence of what?

A

Exogenous unmeasured anions (methanol, ethanol, ketone bodies, etc).

40
Q

The function of magnesium is…

A

Calcium channel blocking agent (affects heart).

41
Q

Magnesium is increased in…

A

Renal failure.

42
Q

Magnesium is decreased in…

A

(1) Cardiac disorders; (2) Diabetes mellitus; (3) Diuretics, alcohol, and other drugs.

43
Q

Testing methods used for magnesium determination.

A

Atomic absorption and colorimetric method.

44
Q

Function of calcium is…

A

Combines with phosphate in bone.

45
Q

What three hormones control calcium levels?

A

(1) PTH; (2) Calcitonin; (3) Vitamin D

46
Q

Hypercalcemia conditions include…

A

(1) Hyperparathyroidism; (2) Cancer with bone metastasis; (3) Multiple myeloma; (4) Renal failure.

47
Q

Hypercalcemia conditions include…

A

(1) Hypoparathyroidism; (2) ↓ serum albumin; (3) ↓ vitamin D.

48
Q

Testing methods for calcium include…

A

(1) Atomic absorption spectroscopy (reference method); (2) Colorimetric method (common); (3) ISE.

49
Q

What preanalytical factor may cause a false decrease in calcium?

A

EDTA contamination.

50
Q

In cases of Tetany, suspect ___ first, then magnesium of potassium.

A

Calcium.

51
Q

The majority of phosphate in the body is expressed as phosphorous; laboratory measures ___ only.

A

inorganic phosphorus (PO4).

52
Q

Phosphorous has an inverse relationship with ___.

A

Calcium; as Calcium ↑, phosphorous ↓.