Clinical Chemistry Flashcards

1
Q

What should you use to palpate the area to feel for a vein when performing a venipuncture?

A

Tip of index finger on non-dominant hand

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2
Q

What is serum?

A

A plasma specimen that clotting factors are added to and anything that doesn’t clot is serum

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3
Q

What is in the plasma of blood?

A

92% Water
7% Proteins = albumin, globulins, fibrinogen, regulatory proteins
1% Other Solutes = electrolytes, nutrients, respiratory gases, and waste products

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4
Q

What can cause a high value for potassium?

A

Hemolysis of blood sample

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5
Q

How are individual electrolyte ions measured?

A

With ion selective electrodes

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6
Q

Where in the blood can electrolytes be found?

A

Serum or plasma

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7
Q

What are ion selective electrodes?

A

A transducer that converts the activity of a specific ion dissolved in solution into an electrical potential which can be measured by voltemeter

It contains a thin membrane across which only the intended ion can be transported

The transport of ions from high concentrations to low concentrations through selective binding sites within the membrane creates a potential difference resulting in an electrical potential

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8
Q

What is the control for ion selective electrodes?

A

External reference electrode

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9
Q

What is the solution for ion selective electrodes?

A

serum or plasma

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10
Q

What is spectrophotometry?

A

Measures change in light absorbance at certain wave lengths

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11
Q

What is an Enzyme Linked Immunoabsorbent Assay (ELISA)?

A

Detects serum antibody or antigen

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12
Q

What is a critical value?

A

any test result that may required rapid clinical attention to avert significant patient morbidity or mortality

Lab will notify provider immediately

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13
Q

What is a Comprehensive Metabolic Panel (CMP)?

A

Basic Metabolic Panel (BMP) + Calcium + Liver Function Studies (LFTs)

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14
Q

What is in a Basic Metabolic Panel?

A
Serum Sodium
Serum Potassium
Chloride
CO2 - blood gas
Blood Urea Nitrogen (BUN)
Creatinine
Glucose - blood sugar
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15
Q

What are other names for a basic metabolic panel?

A

CHEM-7

SMA7

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16
Q

What does Serum Sodium reflect?

A

Changes in water balance rather than sodium balance

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17
Q

What are the functions of serum sodium?

A

Maintain osmotic pressure of extracellular fluid
Acid-base Balance
Neuromuscular Function
Absorption of glucose

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18
Q

What are the causes of Hyponatremia?

A

Hypervolemic hyponatremia (Na is diluted) = CHF

Hypovolemic hyponatremia = dehydration (overall volume depletion)

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19
Q

What are the causes of Hypernatremia?

A

Hypervolemic hypernatremia = CHF

Hypovolemic Hypernatremia (Na is concentrated) = Dehydration (free water deficit)

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20
Q

What is the first symptom of Hyponatremia?

A

weakness

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21
Q

What are the symptoms when Na levels RAPIDLY DROP from 140 to 130 mEg/L?

A
Thirst
Impaired Taste
Anorexia
Dyspnea on exertion
Fatigue
Dulled sensorium
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22
Q

What are the symptoms when Na levels drop from 130 to 120 mEq/L?

A

Severe GI symptoms
vomiting
Abdominal cramps

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23
Q

What are the symptoms when Na levels drop below 115 mEq/L?

A
Confusion
Lethargy
Muscle twitching
Convulsions
Coma
Stupor (brain stem herniation)
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24
Q

What occurs when Na levels are between 110-115 mEq/L?

A

Likely to cause severe and sometimes irreversible neurologic damage like cerebral edema

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25
Q

How do you treat hyponatremia?

A

Treat the underlying cause!

If patient is dehydrated = hydrate them
If patient is fluid overloaded = diurese

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26
Q

What is IV normal saline (IVNS)?

A

0.9% NaCl

Called “Isotonic saline” but is actually inc. Na conc. and volume expanding

Treats dehydration

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27
Q

What is IV1/2NS?

A

0.45% NaCl

Closer to isotonic

Maintenance fluid

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28
Q

What is Lactated Ringers (LR)?

A

Contains NaCl, sodium lactate, KCl, CaCl in water

Used in trauma and surgery

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29
Q

What is hypertonic saline?

A

3% NaCl

Used for sudden precipitous drops in sodium like in a marathon runner

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30
Q

What are the symptoms of Hypernatremia?

A
Dry mucous membranes
Thirst
Agitation
Restlessness
Hyperreflexia
Mania
Convulsions
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31
Q

What is the treatment for Hypernatremia?

A

Administer “free water” in the form of dextrose 5% in water

Cannot administer free water because it will cause hemolysis, so you must include dextrose

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32
Q

What are the dangers of correcting sodium too rapidly?

A

1) Central pontine myelinolysis = confusion, encephalopathy, lethargy, weakness, and paralysis
2) Cerebral edema
3) Brain stem herniation

Last two are associated with Hyponatremia only

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33
Q

What is Central pontine myelinolysis?

A

Destruction of myelin covering nerve cells in the brainstem

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34
Q

What are the normal levels of sodium?

A

135-145 mEq/L

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35
Q

What are the normal levels of K?

A

3.5 - 5.0 mEq/L

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36
Q

What are the functions of serum potassium?

A

Maintain intracellular osmolality
Acid base balance
Transmission of nerve impulses
Essential to skeletal, cardiac, and smooth muscle function

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37
Q

What mechanisms regulate potassium?

A

Insulin

Kidneys

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38
Q

How does insulin regulate potassium?

A

Ingested potassium rapidly enters portal circulation and stimulates the pancreas to release insulin

Elevated insulin stimulates cells to allow glucose to enter and potassium follows into the cells

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39
Q

How do the kidneys regulate potassium?

A

Excess potassium is excreted by the kidneys and eliminated in the urine

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40
Q

What causes Hypokalemia?

A

Inadequate intake
Excessive losses = GI, renal, or skin burns
Redistribution into cells

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41
Q

What causes hyperkalemia?

A

Decreased renal eliminationMOST COMMON
Excessively rapid administration
Movement of potassium from inside the cell to outside the cell like when there is trauma

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42
Q

What are the signs and symptoms of Hypokalemia?

A
Weakness
Muscle Cramps
Paralysis
EKG changes
Cardiac arrhythmias = Afib
Paralytic ileus
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43
Q

What are the signs and symptoms of Hyperkalemia?

A
Weakness
Muscle Cramps
Paresthesias
EKG changes
Cardiac arrhythmias
Intestinal cramping
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44
Q

What is the normal level of Chloride in the blood?

A

98-106 mEq/L

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45
Q

What is the function of chloride?

A

Maintains electrical neutrality by binding to positively charged ions

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46
Q

What is Chloride an indicator of?

A

Hydration status

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47
Q

What are the normal levels of Carbon dioxide in the blood?

A

23-30 mEq/L

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48
Q

What is most CO2 in the form of in the serum?

A

Bicarbonate

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49
Q

What does CO2 indicate?

A

pH status

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50
Q

What is the anion gap?

A

The difference between the primary measured cations and the primary measured anions in serum

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

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51
Q

What is a normal anion gap level?

A

8-16 mEq/L

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52
Q

What are the serum cations?

A

Serum Sodium

Serum Potassium

53
Q

What are the serum anions?

A

Chloride

Bicarbonate

54
Q

What is BUN directly related to?

A

Excretory function of the kidney

55
Q

What can make the BUN levels increase?

A

Changes in protein levels

Excessive upper GI bleeding

56
Q

What do BUN and Creatinine levels primarily measure?

A

Kidney function

57
Q

What are normal levels of BUN?

A

10-20 mg/dL

58
Q

What is azotemia?

A

Elevated BUN levels

59
Q

What is prerenal azotemia?

A

Elevated BUN as result of kidney dysfunction form hypoperfusion

60
Q

What is postrenal azotemia?

A

Elevated BUN levels as a result of post renal obstruction

61
Q

What are normal creatinine levels?

A

0.6-1.2 mg/dL

62
Q

What is creatinine used to indicated?

A

Approximates renal function

GFR

63
Q

What is a BUN:Creatinine ratio of > 20:1 suggestive of?

A

Dehydration

64
Q

What are normal fasting glucose levels?

A

70-110 mg/dL

65
Q

What are normal random glucose levels?

A

< 200 mg/dL

66
Q

What are critical values of glucose levels?

A

<50 or >450 mg/dL

67
Q

What are glucose levels controlled by?

A

Insulin and glucagon

68
Q

What is the function of insulin?

A

Drives glucose into target cells to be metabolized into glycogen

69
Q

What are causes of Hypoglycemia?

A

Starvation
Insulinoma
Hypopituitarism/Hypothyroidism

70
Q

What are the causes of Hyperglycemia?

A

Insulin resistance
Diabetes
Acute stress response like with infections, burns, or surgery

71
Q

How is calcium distributed in the blood?

A

15% bound to organic and inorganic anions

40% bound to albumin

45% physiologically active ionized (free) Calcium

72
Q

What must you do to the levels of Ca provide by the lab?

A

Need to correct the calcium value

Corrected Ca = measured total [Ca] + (0.8 x (4.0 - [albumin]))

73
Q

What causes Hypocalcemia?

A

Impaired ability to mobilize calcium from bone = hypoparathyroidis

Decrease intake or absorption = Vit. D deficiency

Abnormal renal losses = hyperphosphatemia

74
Q

What causes Hypercalcemia?

A

Excessive intake = Vit. D toxicity

Increased bone resorption = hyperparathyroidism

Decreased elimination

75
Q

What are the signs and symptoms of Hypocalcemia?

A
Paresthesias
Skeletal muscle cramps
Tetany (muscle spasms)
Hyperreflexia
Cardiac arrhythmias (prolonged Qt interval)
Bone fractures
76
Q

What are the signs and symptoms of Hypercalcemia?

A
Kidney stones
Anorexia, vomiting, nausea
Muscle weakness/atrophy
Lethargy/coma
EKG changes (shoreted Qt interval)
Hypertension
77
Q

What are the liver function tests?

A
Albumin
Total protein
Alkaline phosphatase (ALP)
Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)
Total bilirubin
Direct bilirubin
Indirect bilirubin
78
Q

What are the normal values of total protein?

A

60-80 g/L

79
Q

What are the normal values of total bilirubin?

A

< 20 micromol/L

80
Q

What are the normal values of total bilirubin?

A

5-40 IU/L

81
Q

What are the normal ALT levels?

A

5-40 IU/L

82
Q

What are the normal ALP levels?

A

30-130 IU/L

83
Q

What are the normal albumin levels?

A

35-50 g/L

84
Q

How is bilirubin formed?

A

Breakdown of hemoglobin and then conjugated in liver

85
Q

What is total bilirubin a count of?

A

Indirect bilirubin = unconjugated

Direct bilirubin = conjugated

86
Q

What does indirect bilirubin indicate?

A

hemolysis

87
Q

What does direct bilirubin indicate?

A

liver and biliary conditions

88
Q

What does an AST to ALT ration of > 2:1 suggest?

A

Alcoholic liver disease

89
Q

What are the normal values of Amylase?

A

25-125 U/L

90
Q

What are the normal levels of lipase?

A

10-140 U/L

91
Q

What tests can be used to indicate acute pancreatitis if increased?

A

Serum Amylase
Serum Lipase
Amylase/Creatinine Clearance

92
Q

What tests can be used to indicate chronic pancreatitis if levels are normal, increased, or decreased?

A

Serum amylase
Serum lipase
Amylase/creatinine clearance

93
Q

What was the old way of diagnosing pancreatitis?

A

If amylase was > 3X the upper limit of normal

94
Q

What do we currently use to diagnose pancreatitis and why?

A

Lipase levels because amylase levels will ris eand fall over a shorter period of time so it was more likely to miss amylase elevation than lipase elevation

Also lipase has a relatively greater pancreas specficity than amylase

95
Q

What are the normal lactic acid levels?

A

0.5 - 1 mmol/L in healthy individuals

96
Q

What is the expected normal of lactic acid levels in those with critical illness?

A

< 2 mmol/L

97
Q

What levels of lactic acid are associated with metabolic acidosis?

A

> 5 mmol/L

98
Q

What does lactic acid quantify?

A

Degree of tissue hypoxia

99
Q

When are lactic acid levels increased?

A

Shock
Vascular occlusion
Ischemic bowel

Elevated in anaerobic metabolism

100
Q

What do troponin I and T indicate?

A

Relatively specific and sensitive biomarkers of cardiac injury

Preferred serologic test for evaluation of ACS

101
Q

What is total creatine kinase?

A

Total of all CK isoenzymes

102
Q

Where is CK-BB (CK1) found?

A

Brain and Lung

103
Q

Where is CK-MB (CK2) found?

A

Myocardial cells

Small amount in skeletal muscle

104
Q

Where is CK-MM (CK3) found?

A

Skeletal muscle

105
Q

What does a total CK:CK-MB ratio > 1.5 indicate?

A

potential cardiac injury

106
Q

What are troponin assays?

A

Sensitive used in the US

Highly sensitive used in Europe, Canada, Australia, and New Zealand

107
Q

What are the pros to high sensitivity troponin assays?

A

Detects MI earlier

108
Q

What are the cons of high sensitivity troponin assays?

A

Also detects troponin elevation in chronic disease
There’s no clear threshold
Risk of unnecessary procedures

109
Q

What is the elevation period of CK-MB?

A

Starts to rise = after 3-6 hours

Peaks = 12-24 hours

Returns to normal = 24-48 hours

110
Q

What is the elevation period of Troponin T?

A

Starts to rise = after 2-6 hours

Peaks = 10-24 hours

Returns to normal = 10 days

111
Q

What is the elevation period of Troponin I?

A

Starts to rise = after 2-6 hours

Peaks = 10-24 hours

Returns to normal = 4 days

112
Q

What is arterial blood gas a measurement of?

A

Patient’s respiratory and metabolic state

Allows us to evaluate gas exchange in the lungs

113
Q

What are the two key things that arterial blood gas gives us?

A

Acid-base balance

Oxygen status

114
Q

What must you perform prior to performing an arterial blood draw?

A

Allen’s test to ensure collateral circulation

115
Q

What are the contraindications for performing an arterial blood gas?

A
No pulse
Cellulitis or compromised skin
No ulnar artery
AV fistula
Coagulaopathy
116
Q

Where can arterial blood be obtained from?

A

Anywhere there is a strong pulse

117
Q

What should you do after performing an arterial blood gas draw?

A

Apply pressure to site for 3-5 minutes or longer if they have a bleeding disorder or are on an anti-coag

Place sample on ice and rush to chemistry lab

118
Q

What will be included in the arterial blood gas report?

A

pH
PCO2
HCO3-

119
Q

What is the normal pH of the blood?

A

7.35-7.45

120
Q

What is the normal pCO2?

A

35-45

121
Q

What is the normal HCO3-?

A

22-26

122
Q

What is metabolic acidosis?

A

Base ions are lost

123
Q

What is Respiratory acidosis?

A

reduced ventiliation causing an increase in pCO2

124
Q

What is Metabolic alkalosis?

A

Acid hydrogen ions are lost; HCO3- ions are relatively high

125
Q

What is Respiratory alkalosis/

A

CO2 is blown off

126
Q

What causes metabolic acidosis?

A

Ketoacidosis
Lactic acidosis
Diarrhea
Renal Failure

127
Q

What causes Respiratory Acidosis?

A

Trauma
COPD
Oversedation

128
Q

What causes Metabolic alkalosis?

A

Hypokalemia
Hypochloremia
High volume gastric suction

129
Q

What causes Respiratory alkalosis?

A

Hypoxemia
CHF
CO poisoning
Pulmonary embolism