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Electrolytes Flashcards

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1
Q

What are the major electrolytes?

A

Sodium, potassium, chloride, and bicarbonate

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2
Q

What is the major extracellular cation?

A

sodium

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3
Q

What is the major intracellular cation?

A

Potassium

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4
Q

What is the major extracellular anion?

A

Chloride

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5
Q

Which hormone regulates the concentration of sodium?

A

Aldosterone

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6
Q

Why should standards for sodium be stored in plastic containers instead of glass?

A

Sodium can leech from glass containers and cause falsely elevated values.

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7
Q

How are sodium and potassium usually measured?

A

By ion selective electrodes (ISE).

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8
Q

What is the approximate ratio of potassium between RBCs and serum?

A

20: 1. This explains why hemolysis must be avoided when measuring potassium.

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9
Q

What are several factors that can cause artifactual (false) elevations of potassium?

A

Fist clenching, prolonged tourniquet time, contamination with K2EDTA or IV fluid, hemolysis, thrombocytosis,
and leukocytosis.

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10
Q

Why is potassium slightly higher in serum than in plasma?

A

Because potassium is released from platelets during clotting.

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11
Q

Before reporting an elevated potassium, what should be checked?

A

The specimen should be checked for hemolysis or excessive delay in separating the serum/plasma from the RBCs. Either could be responsible for a false elevation.

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12
Q

What clinical condition results from very high or very low potassium levels?

A

Cardiac arrhythmias.

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13
Q

What is chloride’s role in the body?

A

It maintains hydration, osmotic pressure, and electrolyte balance.

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14
Q

What is pilocarpine?

A

A topical drug used in the sweat test to stimulate sweat glands.

In iontophoresis, an electric current delivers
pilocarpine nitrate to the sweat glands on the forarm or thigh. Sweat is collected and chloride is measured. A source of error is failure to collect an adequate volume of sweat. The sweat test should be performed at a CF Foundation accredited care center.

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15
Q

What happens to CO2 if the sample is exposed to air?

A

It decreases

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16
Q

What does anion gap measure?

A

Unmeasured anions. The anion gap is increased with renal failure, diabetic acidosis, lactic acidosis, and the presence of drugs or toxins.

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17
Q

What is the most abundant mineral. in the body?

A

Calcium

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18
Q

Which form of calcium is physiologically active?

A

Ionized

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19
Q

Why is pH an important consideration in ionized calcium determinations?

A

As pH decreases (acidosis), calcium dissociates from its complexed forms, increasing the amount of free ionized
calcium in the serum

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20
Q

What is the commonly used method for total calcium?

A

A dye-binding reaction with ortho-cresolphthalein complexone (CPC) or arsenazo III. Atomic absorption is the
reference method but rarely used in clinical labs.

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21
Q

How is ionized calcium measured?

A

By ion selective electrodes.

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22
Q

What substances regulate calcium levels?

A

PTH, calcitonin, and vitamin D.

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23
Q

What is tetany?

A

Muscle spasms, cramps, and irritability due to decreased calcium or magnesiu

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24
Q

What is the most common cause of hypercalcemia?

A

Primary hyperparathyroidism.

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25
Q

How does hyperparathyroidism affect the level of serum phosphorus?

A

Phosphorus is decreased

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26
Q

What happens to calcium when phosphorus is increased?

A

It decreases. There is a reciprocal relationship between calcium and phosphorus.

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27
Q

A hospitalized patient exhibits signs of tetany but her ionized calcium is normal. What other analyte should
be checked?

A

Magnesium. Low levels of magnesium also cause tetany.

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28
Q

How does the reference range for phosphorus in growing children compare to that of adults?

A

It is higher in children.

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29
Q

What must be done to urine prior to performing a urine phosphorus analysis?

A

It must be acidified to pH 6 to prevent precipitation of phosphates.

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30
Q

How does hemolysis affect iron level?

A

Because of the high concentration of iron in hemoglobin, even minimal hemolysis will give falsely elevated results.

To minimize this effect, serum/plasma should be separated from RBCs within one hour of collection and even slightly hemolyzed specimens should not be analyzed.

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31
Q

How are iron levels affected by the time of day when the specimen is drawn?

A

Iron shows a marked diurnal variation. Levels are approximately 30% higher in the morning.

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32
Q

Which protein transports iron?

A

Transferrin. It is normally 20-55% saturated with iron.

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33
Q

Where is most of the iron in the body?

A

In hemoglobin

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34
Q

Name 2 storage forms of iron.

A

Ferritin is the primary storage form. It is present in most cells and is a readily mobilized form of storage iron. A
small amount of iron is also stored as hemosiderin

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35
Q

How are the iron and total iron binding capacity (TIBC) affected in iron deficiency anemia?

A

Serum iron is decreased and TIBC is increased. TIBC is an indirect measurement of transferrin. TIBC is
infrequently performed since the development of improved transferrin assays.

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36
Q

What is the most sensitive test for detection of iron deficiency anemia?

A

Serum ferritin. A decreased serum ferritin is almost always indicative of iron deficiency anemia.

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37
Q

What test results are typical in hereditary hemochromatosis?

A

Serum iron, ferritin, and transferrin saturation are all increased. Total iron binding capacity is decreased.

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38
Q

What is lactate?

A

Lactic acid, an intermediary in carbohydrate metabolism. There are 2 types of lactic acidosis:
• Hypoxic, due to decreased oxygen delivery to the tissues

• Metabolic, associated with disease, drugs/toxins, and inborn errors of metabolism

The mortality rate for lactic acidosis is greater than 60%.

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39
Q

Name a reagent used to measure lactate.

A

Lactate dehydrogenase (LD). Lactate is oxidized to pyruvate by LD in the presence ofNAD+. The NADH formed is measured at 340 nm.

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40
Q

What happens to lactate in the blood following collection?

A

It increases due to glycolysis.

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41
Q

What is a colligative property?

A

One that depends on the number of solute particles, regardless of size or molecular weight. The colligative
properties are osmotic pressure, vapor pressure, boiling point, and freezing point.

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42
Q

How is osmolality usually measured in the clinical lab?

A

By freezing point depression.

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43
Q

What does the urine to serum osmolality ratio indicate?

A

The degree to which the kidneys concentrate the glomerular filtrate. The normal urine:serum ratio is
1:1- 3: 1.

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44
Q

Which substance contributes most to serum osmolality?

A

Sodium accounts for almost half.

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45
Q

What are several clinical conditions that result in an increased serum osmolality?

A

Dehydration, uremia, diabetes mellitus, alcohol intoxication, salicylate intoxication, and excessive electrolyte IVs.

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46
Q

What is osmolal gap?

A

The difference between measured osmolality and calculated osmolality. It is used to diagnose poisonings and to estimate blood alcohol levels. The reference range is 0-10 mOsm/kg. Higher levels indicate an abnormal
concentration of an unmeasured substance such as isopropanol, methanol, ethylene glycol, or acetone.

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47
Q

Our body exists in two environments including:

A

External and Internal

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48
Q

This body environment is subject to heat, cold, noise, physical forces, etc.

A

External

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49
Q

This body environment is relatively constant, consisting of fluids, pH, temperature, electrolytes, etc.

A

Internal

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50
Q

Roughly _____ of our body weight is fluid

A

2/3

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51
Q

Body fluids are contained w/in compartments which are separated by a semi-permeable membrane making some ______ and some ______

A

intracellular fluids, extracellular fluids

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52
Q

All body fluids contain chemical compounds that behave in one of two ways. What are they?

A

1) remain molecularly intact (urea, creatinine, glucose)
2) break up (dissociate) into separate electrically charged particles known as ions or electrolytes

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53
Q

Any substance which, in solution, dissociates into ions and is thus capable of conducting an electric current

A

Electrolytes

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54
Q

Electrolytes exist as positively charged particles known as _________, OR negatively charged particles known as __________.

A

Cations, Anions

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55
Q

The common cations are:

A

-Sodium
-Potassium
-Calcium
-Magnesium

56
Q

The common anions are:

A

-Chloride
-Bicarbonate
-Phosphate
-Sulfate
-Organic Salts

57
Q

The major electrolytes tested for in the lab are:

A

-Sodium
-Potassium
-Calcium
-Magnesium
-Chloride
-Bicarbonate
-Phosphorus

58
Q

Some of the major functions of electrolytes include:

A

-Maintain osmostic pressure
-Regulate hydration of various body fluid compartments
-Maintain pH
-Regulate proper function of heart and muscles
-Oxidation-reduction reactions
-Essential cofactors for enzymes

59
Q

The total concentration of cations w/in the body is on average _______, and _________ for anions. In other words, ____ equals _____ making the body fluids always ___________

A

155 mEq/l, 155mEq/l, positive, negative, electrically neutral

60
Q

One of the most popular tests ordered by the physician regarding electrolytes

A

Serum electrolyte profile

61
Q

A serum electrolyte profile includes:

A

-Sodium
-Potassium
-Chloride
-Bicarbonate (Carbon dioxide)

62
Q

In a normal adult, approximately what percentage of the body’s sodium is bound in the bone structure and is nonexchangeable?

A

30%

63
Q

Sodium intake is dependent on ________, while sodium output occurs through the ________, ________, and ________.

A

dietary intake, GI tract, skin, urine

64
Q

The major route of sodium excretion is:

A

by the kidneys in urine output

65
Q

Sodium is freely filtered by the glomerulus, w/ approx. ____ being reabsorbed as normally less than ______ of filtered sodium is actually excreted.

A

99%, < 1%

66
Q

As the intake of sodium increases or decreases, excretion of sodium increase or decreases ________, to return the extacellular volume to normal

A

Proportionally

67
Q

Excess sodium is termed __________, while a deficiency in sodium is termed __________

A

Hypernatremia, Hyponatremia

68
Q

Inflammation or Edema is typically associated with an increased volume of which electrolyte?

A

sodium

69
Q

Hypernatremia can be a result of which conditions?

A

-Cardiac failure
-Liver disease
-Renal disease causing GFR reduction causing decreased sodium filtration
-Hyperalosternoism
-Pregnancy
-CONGESTIVE HEART FAILURE causing less blood to pump causing less sodium to be filtered

70
Q

Hyponatremia can be caused by:

A

-GI losses
-Excessive sweating
-Renal disease
-Adrenal insufficiency
-Diuretic therapy
-Osmotic diuresis
-Burns

71
Q

T or F: Hypernatremia is dependent on the cause, magnitude, and rate in fall of serum sodium

A

False: Hyponatremia

72
Q

After partial removal from the plasma by glomerular filtration, how much of the potassium is reabsorbed by the tubules?

A

Nearly ALL potassium

73
Q

Almost all of the bodys total potassium is found in the _______ water space.

A

Intracellular

74
Q

Total potassium of the body is influenced by which three factors?

A

Age, sex, and muslce mass (where most body potassium is contained)

75
Q

Potassium output occurs in small amounts from the _______ and ______, but most output is in the ________.

A

GI tract, skin, urine

76
Q

Excess potassium is called ________

A

Hyperkalemia

77
Q

Decreased potassium is called

A

Hypokalemia

78
Q

Of all the electrolytes which one is most affected by hemolysis?

A

Potassium

79
Q

Functions of potassium include:

A

-Cardiac muscle activity
-Acid/base balance
-Osmotic pressure between intra and extracellular

80
Q

A direct method used to determine sodium and potassium and chloride

A

ISE

81
Q

ISE methods can be used to test which specimens?

A

Serum, Urine, CSF

82
Q

Acceptable specimens for sodium and potassium include:

A

Serum, Lithium Heparinized Plasma, Whole Blood, Urine, and other bdoy fluids

83
Q

How long should does the tech have to separate the cells from the specimen for sodium and potassium to avoid shifts?

A

3 hrs.

84
Q

Can I use a hemolyzed sample for a sodium and potassium test?

A

No, hemolyzed specimens will release potassium from the cells causing a false increase in potassium

85
Q

How long is a sodium and potassium and chloride sample good for?

A

-One week @ refrigerated or room temps
-One year frozen

86
Q

Along w/ bicarbonate, this is the most commonly analyzed anion

A

Chloride

87
Q

Electrolyte that assists w/ acid/base balance, water balance, and the formation of concentrated HCl in gastric fluid in the stomach

A

Chloride

88
Q

Chloride increase is termed __________

A

hyperchloremia

89
Q

What is the only condition in which chloride excess MAY NOT be associated w/ sodium excess?

A

Metabolic Acidosis

90
Q

Decrease in plasma chloride is known as _________

A

Hypochloremia

91
Q

What is the only condition in which chloride depletion may occur WITHOUT sodium depletion

A

Metabolic Alkalosis

92
Q

These two electrolytes assist in maintaining the acid/base equilibrium between the plasma and the RBCs

A

Chloride and Bicarbonate

93
Q

What is the difference in the chloride shift in tissue capillaries and the chloride shift in pulmonary capillaries?

A

Tissue capillaries = bicarbonate out, chloride in
Pulmonary capillaries = bicarbonate in, chloride out

94
Q

This electrolyte is also known as carbon dioxide

A

bicarbonate

95
Q

Bicarbonate is formed in the kidney by an enzymatic reaction catalyzed by the enzyme ____________

A

carbonic anhydrase

96
Q

Electrolyte that controls acid/base balance by maintaining a 20:1 ratio w/ carbonic acid to control blood pH, as well as controlling water balance

A

Bicarbonate

97
Q

What is the bicarbonate to carbonic acid ratio maintained?

A

20:1

98
Q

This condition is primarily due to an excess of carbon dioxide; increased C02 retention in an excess production of carbonic acid

A

Respiratory Acidosis

99
Q

This condition is primarily due to a deficit in carbon dioxide; bicarbonate is converted to carbonic acid in the kidney to compensate and replace the decreasing carbonic acid

A

Respiratory Alkolosis

100
Q

Main cause of Respiratory Alkalosis is contributed to:

A

hyperventilation syndrome seen in hysteria, anxiety, high fever, drugs

101
Q

When testing samples for carbon dioxide, it is important to remember to:

A

cap the specimen, as false decrease of carbon dioxide will occur after it is released in as little as 1 hr

102
Q

What percentage of the magnesium in the body is associated w/ two ions in the bones, Calcium and Phosphorous?

A

> 50%

103
Q

This electrolyte is the principle cation of soft tissues

A

Magnesium

104
Q

What percent of magnesium in the body is actually in the blood?

A

1%

105
Q

The major clinical symptoms of magnesium disorders are _____________ related

A

Neuromuscular

106
Q

One method of magnesium measurement involves using this dye for direct determination w/o proteinization by forming a pink magnesium-calmagite complex

A

Metallochromatic dye

107
Q

If the specimen is not separated from the clot asap, magnesium will be ___________ due to its elution from the RBCs as the RBCs contain 3x more magnesium than plasma

A

Falsely increased

108
Q

Are hemolyzed samples okay for use when detecting magnesium?

A

No, it will falsely increase the specimen as RBCs contain 3x more magnesium than plasma

109
Q

The specimen of choice for magnesium detection is:

A

Serum

110
Q

This is the most abundant mineral in the body

A

Calcium

111
Q

Of the total body calcium, what percentage is located w/in the bones and teeth?

A

99%

112
Q

With 99% of total body calcium in the bones and teeth, where does the other 1% lie?

A

Blood and soft tissues

113
Q

What is the breakdown of the remaining 1% of total body calcium?

A

50%- Ionized Free Calcium (active)
45%- Protein-bound (primarily albumin) (inactive)
5%- Organic Complexes

114
Q

Functions of Calcium include:

A

-Bone and Teeth formation
-Coagulation factor of blood
-Conduction of nerve impulses
-Muscle contraction and relaxation
-Alters plasma membranes to allow transport of certain ion in and out of the cell
-Essential ingredient of the “glue” in connective tissue
-Cofactor of many enzymes

115
Q

There is an _________ relationship between calcium and phosphorous.

A

inverse

116
Q

Calcium is absorbed in the small intestine and is greatly enhanced by an ________ pH and greatly decreased by an ________ pH

A

Acid Alkaline

117
Q

The presence of this is essential to the absorption of calcium

A

Vitamin D

118
Q

Calcium is excreted mostly through the ________, as non-absorbed calcium is excreted in the feces.

A

GI Tract

119
Q

Hypercalcemia can be caused primarily by:

A

malignancy, hyperparathyriodism

120
Q

What calcium disorder is of concern to neonates?

A

Hypocalcemia

121
Q

A hormone secreted by the parathyroid glands in response to LOW calcium levels

A

PTH

122
Q

Hormone secreted by the thyroid gland in response to HIGH calcium levels

A

Calcitonin

123
Q

Active component of Vitamin D; synthesized in the skin when exposed to UV light but may also be ingested in food sources

A

Calcitriol

124
Q

What is the principle/methodology for calcium detection?

A

Metabolic indicator or dyes

125
Q

What two dyes are widely used today for the metallochromic indicators when testing calcium?

A

OCPC and Arsenzo III

126
Q

If an anticoagulant is used ________ and ______ should be avoided as they chelate calcium

A

EDTA, Oxalates

127
Q

What percentage of phosphorous is bound up in the bones and teeth?

A

80%

128
Q

What are the functions of phosphorous?

A

-Bone and teeth formation
-Carb metabolism
-Backbone of nucleic acids
-Buffer in acid/base balance

129
Q

T or F: Phosphorous deficiencies are common

A

F. Phosphate deficiencies are unheard of due to the abundance of phosphorous in our diets.

130
Q

Hyperphosphatemia can occur as a result of:
]

A

-Hypervitaminosis D
-Hypoparathyroidism
-Kidney Failure

131
Q

Hypophosphatemia can occur as a result of:

A

-Rickets
-Hyperparathyroidism
-Fanconi Syndrome

132
Q

Increased calcium levels may cause:

A

muscle paralysis and coma

133
Q

This type of specimen will give more accurate results when testing for phosphorous

A

Fasting specimens

134
Q

if the concentrations of the two major plasma anions are added and subtracted from the sum of the two major cations, the difference is called the __________.

A

Anion Gap

135
Q

What is the formula for the anion gap?

A

(Na + K) - (Cl + HCO3)

136
Q

A low anion gap is of some diagnostic value as the most important cause of low anion gap is ____________

A

Multiple Myeloma

137
Q

The most significant function of an electrolyte is to:

A

Acid, base balance

Clinical Chemistry (7 decks)

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