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Intro to Clinical Medicine > Introduction to Laboratory medicine > Flashcards

Introduction to Laboratory medicine Flashcards

1
Q

Characteristics of Population

3

A
  1. Sufficiently high prevalence of disease
  2. Likely to be compliant with subsequent tests and treatments
  3. Those that would be noncompliant-let it take its course. Part of their beliefs
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2
Q

Characteristics of Disease

4

A
  1. Significant morbidity and mortality
  2. Effective and acceptable treatment available
  3. Presymptomatic period detectable
  4. Improved outcome from early treatment
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3
Q

Characteristics of Test

3

A
  1. Good sensitivity and specificity
  2. Low cost and risk
  3. Confirmatory test available and practical
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4
Q

How does screening help our diagnosis?

4

A
  1. To help establish or exclude the presence of disease in symptomatic persons
  2. Assist in early diagnosis after onset of signs and symptoms
  3. Assist in developing a differential diagnosis
  4. Help determine the stage or activity of disease
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5
Q

What can lab tests and screening be used for in patient management?
5

A
  1. Evaluate the severity of disease
  2. Estimate prognosis
  3. Monitor the course of disease (progression, stability, or resolution)
  4. Detect disease recurrence
  5. Select drugs and adjust therapy (treatment plan)
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6
Q

What do we want to consider when ordering a test?

4

A
  1. Cost (panel might be cheaper than two tests)
  2. Associated risks (how dangerous the test is)
  3. Potential for additional testing
  4. Will the result of the test change what i will do after?
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7
Q

Types of test results?

A

Qualitative (either pos or neg) and Quantitative (measured amount reported in mass or volume)

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8
Q

What is the purpose of reference intervals or reference ranges?

A

Establish a normal range to compare results to

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9
Q

What is the reference interval dependant on?

A

Lab and population

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10
Q

How is the reference range determined?

A

by sampling a healthy population

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11
Q

What percent of the result determine the normal range?

A

95%

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12
Q

What happens to the other 5% of the reference interval that isnt used?

A

Throw out the top and bottom 2.5% so in fact up to 5% of normal values may fall outside that particular reference range

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13
Q

So if someone has a Ca level of 8.4 or 10.4 what do we do?

Exception?

A

we do nothing because the range is big (1.7). We say that it is ok because its still in the 2.5% that we threw out.

Unless its a big change in the normal range like from 8.4 to 10.2 then we probably want to check into it/retest.

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14
Q

If someone has a creatinine level of 1.4mg what would we do?

A

For creatinine its a whole different story because the range is 0.6-1.2mg. If you have a 1.4 is that close enough? no!!!!!!
Because your drug range is really narrow (normal range only spans 0.6 so you take that more seriously) smaller reference range

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15
Q

What would cause normal differences in Hb or hemocrit levels?
2

A

normal range for patient at sea level will be different for a patient at 6000 feet

Men or woman

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16
Q

Physiologic factors which may influence test results (not factored into reference ranges)?
11

A 
Medications
Altitude
Occupational and environmental exposures
Age
Gender
Exercise
Diet/fasting status
Pregnancy
Diurnal variations
Tobacco use
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17
Q

What is accuracy determined by?

A

Determined by its correspondence with the true value

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18
Q

How is accuracy maximized?

A

calibration of laboratory equipment with standard reference material (quality control measures)

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19
Q

What does precision measure?

A

measures the tests reproducibility

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20
Q

What is the coefficient of variation?

A

Even precise tests will vary slightly upon repeating. (how much a tests varies/degree of precision)

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21
Q

Sesitivity indicated what?

A

the presences of the disease

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22
Q

How is sensitivity expressed?

A

as the percentage of patients with disease in whom the test is positive

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23
Q

If a test has a sensitivity of 90% what does that tell us?

A

gives positive results in 90% of diseased patients and negative results in 10% of diseased patients (false negatives)

100 people have proven disease then 90% will show disease and 10% will be false negative

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24
Q

Whats true positive?

A

Abnormal test results occurring in individuals who have disease

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25
Q

Whats a false negative?

A

Normal rest results occurring in individuals who have the disease

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26
Q

Equation for sensitivity?

A

TP/(TP + FN)

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27
Q

Whats an example of a test that needs to be highly sensitive?

A

HIV

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28
Q

What is sensitivity helpful in ruling about the disease?

A

SNOut – a highly Sensitive test with a Negative result is helpful for ruling Out the disease

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29
Q

Specificity indicates what?

A

absense of the disease

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30
Q

How is specificity expressed?

A

as the percentage of patients without disease in whom the test is negative.

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31
Q

If a test has a specitivity of 90% what does that tell us?

A

gives negative results (true negatives) in 90% of patients without disease and positive results (false positives) in 10% of patients without disease.

100 patients without the disease then 90% will test neg and 10% will be false positives

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32
Q

What is a true negative?

A

Normal test results in a disease-free healthy individual

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33
Q

What is a false positive?

A

Abnormal test results in a disease-free healthy individual

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34
Q

Equation for specificity?

A

TN/(TN + FP)

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35
Q

Example of a highly specific test?

A

A highly specific test to check for gout would be an evaluation of the joint fluid for the presence of urate crystals (there is nothing else that causes this!)

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36
Q

What is specificity helpful in ruling a disease?

A

a highly Specific test with a Positive result is helpful for ruling In the disease

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37
Q

What is the pretest probability?

A

The likelihood the patient has the abnormality that you are testing for based on risk factors, symptoms, history and physical exam

No labs yet

How suspicious you are that the patient has the disease- based on how well you know the disease

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38
Q

If you have a pretest probabilty of one how certain are you that they have the disease?

A

very certain

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39
Q

Which would be a better diagnosis for a patient seen in a medical clinic in Cheyenne, WY for fever and chills? Malaria or UTI?

A

UTI because of high pretest probability

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40
Q

What does a high pretest probabilty help us to accomplish?

A

more accurate testing and lab/procedure ordering

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41
Q

Example of when you need a single test instead of a panel (which might be cheaper and more comprehensive?)

A

Many health fairs check just total cholesterol to screen for lipid disorders. If the total cholesterol is abnormal then you would need a lipid panel prior to treating the patient.

42
Q

What does a BMP consist of?

8

A

Na, K, Cl, CO2, GLU, BUN, Creatinine, Ca

43
Q

What does a CMP consist of?

14

A

Na, K, Cl, CO2, GLU, BUN, Creatinine, Ca, TP, ALB, AST, ALT, ALP, T. BILI I

44
Q

Whats in a liver funciton panel?

6

A

ALB, AST, ALT, ALP, T. BILI I, D. BILI I

45
Q

Whats in a renal fucntion panel?

10

A

Na, K, Cl, CO2, GLU, BUN, Creatinine, Ca, ALB, Inor P

46
Q

Whats the differene b/w a basic metabolic profile compared to a comprehensive one?

A

Comprehensive are more costly and you dont necessarily need them most of the time

47
Q

Where is magnesium on the panels?

A

Its not on there. you have to order it separetely

48
Q

Why is sodium blood testing done?
3

What could high levels of sodium be caused by?
5

A
  1. Check the water and electrolyte balance of the body.
  2. Find the cause of symptoms from low or high levels of sodium.
  3. Check the progress of diseases of the kidneys or adrenal glands.
  4. dehydration
  5. Severe vomiting or diarrhea
  6. Cushings syndrome
  7. kidney disease
  8. increased aldosterone
49
Q

What can decreased levels of sodium indicate (hyponatremia)?
8
4 surface
4 disease related

A
  1. excessive sweating
  2. burns
  3. severe vomiting or diarrhea
  4. drinking too much water/low sodium diet
  5. Underactive adrenal glands
  6. CHF
  7. kidney disease
  8. cirrhosis
50
Q

Function of Na in the body?

4

A
  1. conduction of neuromuscular impulses via sodium pump, (sodium shifts into cells as the potassium shifts out for cellular activity);
  2. enzyme activity,
  3. osmolality of intravascular fluid;
  4. the regulation of acid-base balance,
51
Q

Why do we test for BUN?
4

High BUN values can indicate? 5

Low BUN values can indicate?4

A
  1. kidneys are working normally
  2. kidney disease is getting worse
  3. treatment of kidneys is working
  4. check for severe dehydration
  5. kidney injury or disease
  6. medications
  7. high protein diet
  8. Addisons disease
  9. GI bleeding
  10. low protein diet
  11. Overhydration
  12. being a woman or a child
  13. rhabdomyolysis/cirrhosis
52
Q

What is CO2 testing for?
2

What could high levels of bicarbonate indicate?8

What could low values of bicarbonate indicate?6

A

This test references lung and kidney function

  1. Vomiting
  2. Dehydration
  3. blood transfusions
  4. Over use of antacids
  5. Anorexia
  6. COPD
  7. pulmonary edema
  8. Cushings
  9. Hyperventilation
  10. aspirin or alcohol overdose
  11. dehydration
  12. liver or kidney disease
  13. Massive MI
  14. hyperthyroidism/uncontrolled diabetes
53
Q

What are creatinine levels testing?

A

Creatinine levels can tell your doctor how your kidneys are functioning.

54
Q

What would a high creatinine level indicate?

What would a low creatinine level indicate?

A
  1. kidney problems (kidney failure)
  2. muscle diseases
  3. preclampsia
  4. myasthenia gravis
  5. muscular dystrophy
55
Q

What is the fucntion of Cl?

A

to maintain fluid balance

56
Q

What can disproportionate loss of chloride lead to in the body?

A

Lead to the body’s environment becoming more acidic (low pH levels)

57
Q

What is potassiums major role in the body?

A

he major electrolyte inside cells. Its passage in and out of cells is essential to regulate heart contractions

58
Q

Low K results in what?

A

Low potassium levels also increase the risk of dangerous, abnormal heartbeat and are associated with muscle weakness

59
Q

What is TP?

A

Total protein or Albumin/Globulin ratio

60
Q

What is TP used to test?

6

A 
kidney disease
liver disease
nutritional status
unexplained weight loss
bone marrow disorder
edema
61
Q

What could low TP suggest?

4

A

kidney disease
liver disease
nutritional status
Malabsorption/Malnutrition

62
Q

What could a high TP suggest?

4

A

Chronic inflammation
viral hep
HIV
multiple myeloma

63
Q

What is GLU function in the body?

A

main source of energy

64
Q

What does GLU testing tell us?

A

Prediabetic or diabetic

Hypoglycemia

65
Q

Conditions that can cause high blood glucose levels?

6

A 
Diabetes!
Severe stress.
Heart attack.
Stroke.
Cushing's syndrome.
Medicines such as corticosteroids.
Excess production of growth hormone (acromegaly).
66
Q

Conditions that can cause low blood glucose levels?

8

A 
Insulinoma
Addison's disease.
Decreased thyroid hormone levels (hypothyroidism).
A tumor in the pituitary gland.
Liver disease, such as cirrhosis.
Kidney failure.
Malnutrition or an eating disorder, such as anorexia.
Medicines used to treat diabetes.
67
Q

Why is calcium testig done?

3

A
  1. Check with problems with parathyroid glands and kidneys
  2. Abnormal EKG
  3. After a kidney tranplant
68
Q

What could high Ca be caused by?

5

A
  1. Hyperparathyroidism.
  2. Cancer, including cancer that has spread to the bones.
  3. Tuberculosis.
  4. Being on bed rest for a long time after a broken bone.
  5. Paget’s disease.
69
Q

What could high Ca be caused by?

6

A
  1. A low level of the blood protein albumin (hypoalbuminemia).
  2. Hypoparathyroidism.
  3. High levels of phosphate in the blood, which can be caused by kidney failure, laxative use, and other things.
  4. Malnutrition caused by diseases such as celiac disease, pancreatitis, and alcoholism.
  5. Osteomalacia.
  6. Rickets.
70
Q

Why is Albumin tested?

6

A
  1. Check how well the liver and kidneys are working.
  2. Find out if your diet contains enough protein.
  3. Help determine the cause of swelling of the ankles (edema) or abdomen (ascites) or of fluid collection in the lungs that may cause shortness of breath (pulmonary edema).
71
Q

High Albumin levels may be caused by?

A

Severe dehyrdation

72
Q

Low albumin levels may be caused by?

8

A
  1. A poor diet (malnutrition).
  2. Kidney disease.
  3. Liver disease.
  4. An autoimmune disease, such as lupus or rheumatoid arthritis.
    Gastrointestinal malabsorption syndromes, such as sprue or Crohn’s disease.
  5. Hodgkin’s lymphoma.
  6. Uncontrolled diabetes.
  7. Hyperthyroidism.
  8. Heart failure.
73
Q

Why is AST (aspartate aminotransferase) done?

5

A
  1. Check for liver damage.
  2. Help identify liver disease, especially hepatitis and cirrhosis. Liver disease may produce symptoms such as pain in the upper abdomen, nausea, vomiting, and sometimes jaundice.
  3. Check on the success of treatment for liver disease.
  4. Find out whether jaundice was caused by a blood disorder or liver disease.
  5. Keep track of the effects of medicines that can damage the liver.
74
Q

What would high levels of AST be caused by?

7

A
  1. Liver damage from conditions such as hepatitis or cirrhosis.
  2. A heart attack or heart failure.
  3. Many medicines, such as statins, antibiotics, chemotherapy, aspirin, narcotics, and barbiturates.
  4. High doses of vitamin A.
  5. Kidney or lung damage.
  6. Mononucleosis.
  7. Some types of cancer.
75
Q

Why is Alanine Aminotransferase (ALT) done?

4

A
  1. Identify liver disease, especially cirrhosis and hepatitis caused by alcohol, drugs, or viruses.
  2. Help check for liver damage.
  3. Find out whether jaundice was caused by a blood disorder or liver disease.
  4. Keep track of the effects of medicines that can damage the liver.
76
Q

What could high levels of ALT be caused by?

7

A
  1. Liver damage from conditions such as hepatitis or cirrhosis.
  2. Lead poisoning.
  3. Exposure to carbon tetrachloride.
  4. Decay of a large tumor (necrosis).
  5. Many medicines, such as statins, antibiotics, chemotherapy, aspirin, narcotics, and barbiturates.
  6. Mononucleosis.
  7. Growth spurts, especially in young children. Rapid growth can cause mildly elevated levels of ALT.
77
Q

Why is Alkaline Phosphatase (ALP) done?

4

A
  1. Check for liver disease or damage to the liver. Symptoms of liver disease can include jaundice, belly pain, nausea, and vomiting.
  2. An ALP test may also be used to check the liver when medicines that can damage the liver are taken.
  3. Check bone problems (sometimes found on X-rays), such as rickets, bone tumors, Paget’s disease, or too much of the hormone that controls bone growth (parathyroid hormone).
  4. The ALP level can be used to check how well treatment for Paget’s disease or a vitamin D deficiency is working.
78
Q

What can high values of ALP suggest?

4

A
  1. Very high levels of ALP can be caused by liver problems, such as hepatitis, blockage of the bile ducts (obstructive jaundice), gallstones, cirrhosis, liver cancer, or cancer that has spread (metastasized) to the liver from another part of the body.
  2. High ALP levels can be caused by bone diseases, such as Paget’s disease, osteomalacia, rickets, bone tumors, or tumors that have spread from another part of the body to the bone, or by overactive parathyroid glands (hyperparathyroidism). Normal healing of a bone fracture can also raise ALP levels.
  3. Heart failure, heart attack, mononucleosis, or kidney cancer can raise ALP levels. A serious infection that has spread through the body (sepsis) can also raise ALP levels.
  4. Women in the third trimester of pregnancy have high ALP levels because the placenta makes ALP.
79
Q

What can low values of ALP cause?

A

Conditions that lead to malnutrition (such as celiac disease) or are caused by a lack of nutrients in the diet (such as scurvy) can cause low ALP levels.

80
Q

Why is total bilirubin done?

4

A
  1. Check liver function and watch for signs of liver disease, such as hepatitis or cirrhosis, or the effects of medicines that can damage the liver.
  2. Find out if something is blocking the bile ducts. This may occur if gallstones, tumors of the pancreas, or other conditions are present.
  3. Diagnose conditions that cause increased destruction of red blood cells, such as hemolytic anemia or hemolytic disease of the newborn.
  4. Help make decisions about whether newborn babies with neonatal jaundice need treatment. These babies may need treatment with special lights, called phototherapy. In rare cases, blood transfusions may be needed.
81
Q

High levels of bilirubin may indicate?

6

A
  1. Some infections, such as an infected gallbladder, or cholecystitis.
  2. Some inherited diseases, such as Gilbert’s syndrome, a condition that affects how the liver processes bilirubin. Although jaundice may occur in some people with Gilbert’s syndrome, the condition is not harmful.
  3. Diseases that cause liver damage, such as hepatitis, cirrhosis, or mononucleosis.
  4. Diseases that cause blockage of the bile ducts, such as gallstones or cancer of the pancreas.
  5. Rapid destruction of red blood cells in the blood, such as from sickle cell disease or an allergic reaction to blood received during a transfusion (called a transfusion reaction).
  6. Medicines that may increase bilirubin levels. This includes many antibiotics, some types of birth control pills, diazepam (Valium), flurazepam, indomethacin (Indocin), and phenytoin (Dilantin).
82
Q

Low levels of bilirubin may be caused by what?

A

Medicines that may decrease bilirubin levels. This includes vitamin C, phenobarbital, and theophylline.

83
Q

Why test for D. Bili?

A

The amount of free Bilirubin in your blood and urine

- test if you get an abnormal total bilirubin

84
Q

What side effects (5) would make you want to test a Bili level and what could be the causes of these side effects? 3

A
  1. Jaundice, or yellowing of your skin and whites of your eyes
  2. Dark-colored urine
  3. Nausea
  4. Vomiting
  5. Fatigue
  6. You may also have this test if you drink a lot of alcohol on a regular basis (liver damage)

You may also need this test if your doctor suspects that you may have:

  1. Hepatitis.
  2. Gallstones.
  3. Inflammation of the bile duct.
85
Q

Why do we test inor p? (inorganic phosphate)3

A

Check for bone, parathyroid and renal disease

86
Q

Hypophosphatemia may have 4 general causes

A
  1. shift of phosphate from extracellular to intracellular,
  2. renal phosphate wasting,
  3. loss from the gastrointestinal tract, and
  4. loss from intracellular stores.
87
Q

Hyperphosphatemia is caused by?

2

A
  1. an inability of the kidneys to excrete phosphate.

2. Other factors may relate to increased intake or a shift of phosphate from the tissues into the extracellular fluid.

88
Q

What three types of cells are measured in a CBC?

A

White blood cells

Red blood cells

Platelets

89
Q

What is the difference b/w a WBC and a WBC differential? 5

A 
White blood cell count
-Total number of all white blood cells in the sample
White blood cell differential
-Percentage of the different types of white blood cells
--Neutrophils
--Lymphocytes
--Monocytes
--Eosinophils
--Basophils
90
Q

When do you order an WBC differential?

A

Everytime you suspect an infection

91
Q

Whats an RBC?

A

Actual number of red blood cells

92
Q

What are you checking for in a Hb?

A

Hemoglobin

The amount of oxygen carrying protein in the blood

93
Q

What are you checking for in a hematocrit?

A

The percentage of a person’s blood that consists of red blood cells

94
Q

What does MCV mean?

A

Mean corpuscular volume

-defines the size of the red blood cells

95
Q

What does MCH mean?

A

mean corpuscular hemoglobin

  • quantifies the amount of hemoglobin per red blood cell
  • Average amount of oxygen carrying hemoglobin
96
Q

What does MCHC mean?

A

mean corpuscular hemoglobin concentration

-Average percentage of hemoglobin inside the RBCs

97
Q

What does RDW mean?

A

red cell distribution width

-represents the coefficient of variation of the red blood cell volume distribution (size)

98
Q

What are reticulocytes and why do we test for them 2?

A

immature red blood cells-dont usually come with CBC.

  1. Chronic bleeding and if bone marrow was working = high reticulocytes.
  2. If its acute bleeding it wont be that way because bone marrow hasnt responded yet
99
Q

Three reasons not to order an unecessary test?

A
  • costs a lot of money
  • could be abnormal and then you have to chase is down
  • unethical = don’t want to be accused of fraud even if it’s unintentional
100
Q

Whats an ICD?

A

A diagnosis code for why you are having the test/lab done

101
Q

Whats a CPT?

A

A diagnosis code for why you are having the procedure done

102
Q

Approved CPT’s are paired with what?

A

ICD codes and DRGs

Intro to Clinical Medicine (12 decks)

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