Intro to Lab Medicine & Common Lab Tests Flashcards by Elizabeth Sager

Define reference range

range of values within a population of people who do not have a given disease
- upper and lower limits
- can vary from lab to lab
- usually central 95%

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Define desirable range

prognosis related ranges
associate lab results with clinical outcomes - can be a goal rather than a normal result

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Define therapeutic range

can measure effectiveness of a medication or
screen for possible toxicity

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Define laboratory threshold

a value that is set to catch presence of disease above a threshold, can result in false positives or false negatives

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Sensitivity focuses on a population of individuals who ____ the disease

have the disease

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Define sensitivity

capacity to identify individuals with the disease

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Sensitive tests have ____ diagnostic thresholds and specific tests have ____ diagnostic thresholds

low (more false positives), high (more false negatives)

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Define specificity

how effective a test is at correctly identifying people without disease

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Specificity focuses on a population of individuals who _____ the disease

don’t have the disease

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Positive predictive value focuses on people with a _____ test result, negative predictive value focuses on people with a ____ test result

positive, negative

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Positive predictive value predicts the likelihood that…

a positive test identifies someone with the disease (TB test in community with high prevalence)

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Negative predictive value predicts the likelihood that…

a negative test result identifies someone without the disease (D-dimer)

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Define prevalence

number of existing cases in a population (expressed as a percent)

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Define incidence

number of new cases occurring within a period of time (expressed as a number per year)

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Reasons for ordering a test

diagnosing a disease
monitoring a disease/interventions
screening for a disease
research

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Questions to ask before ordering a test

why is it being ordered
what are the consequences of not ordering
how sensitive/specific is the test
how are the results interpreted
how will the test results influence patient management

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3 phases of the lab testing cycle

pre-analytic
analytic
post-analytic

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When do most errors occur within lab testing

in the pre-analytic phase

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Define the rifle approach

ordering specific tests based on diagnostic accuracy and predictive value

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Define the shotgun approach

indiscriminately ordering a large number of tests

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What does a pale yellow to amber color urine specimen mean?

Normal

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What does a straw color urine specimen mean?

normal but low specific gravity (hydrated)

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What does an amber color urine specimen mean?

normal but high specific gravity (dehydrated)

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What can colorless urine mean?

large fluid intake
diabetes mellitus
diabetes insipidus

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What can turn urine orange?

Pyridium/AZO

What can turn urine reddish or dark brown?

- blood (RBCs) - hemoglobin - myoglobin

What does high specific gravity mean

dehydration

what does low specific gravity mean?

hydrated (also diabetes insipidus)

Low pH means

acidic

High pH means

basic

Acidic urine can mean...

uncontrolled DM - ketoacidosis

alkaline urine can mean...

UTI (bacteria strains sometimes)

Hematuria means

blood in the urine

Common/Important clinical implications of hematuria

- lower UTI - nephrolithiasis - urinary tract cancers - renal cancers - urinary catheter - anticoagulants - strenuous exercise

Clinical implications of proteinuria

kidney diseases

Proteinuria means

protein in the urine (mild, moderate, severe)

The presence of _____ in the urine is the single most important indication of renal disease, even in an apparently healthy person if persistent

protein

Term for increased urinary glucose is

glucosuria or glycosuria

increased glucosuria can mean someone has...

diabetes mellitus

Positive urine glucose requires evaluation for which disease

diabetes

ketonuria

term for increased urinary ketones

clinical implications of ketonuria

- diabetes mellitus (ketoacidosis) - starvation/fasting

False positive for urinary ketones can be caused by

dehydration and medications

Urine nitrite is a marker for _____

bacteria

One interfering factor for urine nitrite is

pyridium/AZO (false positive)

Clinical implications of urine leukocyte esterase presence is

UTI

False positive for urine leukocyte esterase can be cased by

vaginal discharge, infections, contamination

False negative for leukocyte esterase can be caused by

pyridium/azo

Increased levels of urinary bilirubin involve this organ

the liver

Increased urobilinogen has clinical implications for ____ and _____

hemolysis and liver disease

What is the timeframe for urine testing

one hour unless refrigerated

What does the presence of casts in urine microscopy indicate?

kidney issues

Bacteria in the urine resemble this food item

sprinkles

WBCs in the urine resemble this food item

increased WBCs in the urine can be caused by ____, ____, _____, and _____

UTI, stones, cancer, inflammation

RBCs in the urine resemble this food item

donuts

clinical implications of RBCs in the urine are

UTI, renal cancer, bladder cancer, kidney stones

presence of squamous epithelial cells in the urine indicate

contamination of the sample

RBC casts indicate_____

hemorrhage and are always pathologic - glomerulonephritis

WBC casts indicate

pyelonephritis

think ____ disease if there is protein in the urine

kidney

check for ____ if there is glucose in the urine

diabetes

blood in the urine requires investigation true or false

true

positive nitrites and positive LE can mean

infection

casts are associated with this organ

kidneys

What medications should be considered when ordering a urine test

Vit C and pyridium/AZO

CBC means

complete blood count

What are the 5 things counted in a CBC

WBCs RBCs platelets hemoglobin hematocrit

Leukocytes is a term for

WBCs

leukocytosis means

increased WBCs

leukopenia means

decreased WBCs

CBC with differential includes

the 5 types of WBCs and the percentage and absolute count for each

How many types of WBCs are there

List the types of WBCs

neutrophils lymphocytes eosinophils monocytes basophils

What may be indicated in leukocytosis

infection or inflammation

What med may cause leukocytosis

prednisone

Causes of leukopenia include

viral infections BAD bacterial infections (sepsis)

What is the most numerous WBC

neutrophil

What WBC is the primary defense

neutrophil

High neutrophil count is called

neutrophilia

Causes of neutrohphilia include

Bacterial infection, inflammation, steroids like prednisone

Neutropenia means

low neutrophils

Causes of neutropenia include

sepsis or viral infection

The 3 types if lymphocytes are

B cells, T cells, natural killer cells

What do lymphocytes do

migrate to areas of inflammation

Lymphocytosis can be caused by infections like

mononucleosis (viral)

lymphopenia can be caused by

chemo and radiation, AIDS (low T cells)

Eosinophils kill invaders with

toxic chemicals in granules

Think ___ ____ and ____ with eosinophilia

wheezes, sneezes and weird diseases

Basophils produce ____

histamine

Basophilia can be caused by

inflammation from allergies

What is the second line of defense WBC?

monocytes

monocytosis can be caused by

infections and through recovery

What do RBCs do

carry oxygen to tissue and CO2 back to lungs

RBCs use what to carry oxygen

hemoglobin (needs iron)

Does RBC count differ between men and women?

yes

define erythrocytosis

increased RBC count

define erythrocytopenia

decreased RBC count

One cause of erythrocytosis includes

polycythemia vera

one cause of erythrocytopenia includes

anemia

Hgb test checks for _____

anemia (differs between men and women)

Hct is the ______

% of RBCs within entire blood and differs between men and women

Hct = Hgb x 3

Role of platelets

blood clotting, vasoconstriction

Thrombocytosis

increased platelets

Thrombocytopenia

decreased platelets

Thrombocytosis can be caused by

cancers (leukemia) and acute infections

Thrombocytopenia can be caused by

some infections, liver disease (cirrhosis)

BMP components

sodium, potassium, chloride, HCO3-, blood urea nitrogen (BUN), creatinine, serum glucose, can include calcium

What is the primary cation in extracellular fluid

Sodium (Na+)

Hypernatremia

increased serum sodium

Hyponatremia

decreased serum sodium

What is the primary cation in the intracellular fluid

Potassium (K+)

changes in serum K+ can affect

nerves, nuscles, heart

Hyperkalemia = ____ potassium, Hypokalemia = ____ potassium

high, low

If blood sample gets hemolyzed, potassium _____ the cells and can cause a falsely _____ potassium level

leaves, elevated

What is the primary anion in the extracellular fluid

Chloride (Cl-)

Hyperchloremia and Hypochloremia

high and low chloride

Alkalosis = ____ _____, Acidosis = ____ _____

increased bicarbonate, decreased bicarbonate

Increased BUN can mean

kidney insufficiency, urinary tract obstruction

Decreased BUN can mean

low protein diet

Elevated creatinine means decreased ____ function

renal

Does creatinine differ in men and women

yes

Should the glomerular filtration rate be lower or higher

higher, low = bad

What is the glomerular filtration rate

how well the kidneys are working

What can a GFR be part of?

BMP

Anion Gap (AG) tells diference between

serum cations and anions

serum glucose can be caused by

diabetes and severe infection and steroids

hypoglycemia and hyperglycemia refer to ____ ____

serum glucose

Hypercalcemia is associated with

heart problems

hypocalcemia is associated with

muscle contractions, seizure

increased serum calcium is associated with

hyperparathyroidism (bone breakdown), too much Vit D

decreased serum calcium is associated with

hypoparathyroidism, Vit D deficiency

Hgb A1C tells us what

average blood sugar over past 6-12 weeks and tests for diabetes mellitus

What can confound Hgb A1c

pregnancy

Increase serum amylase is associated with

pancreatitis

decreased serum amylase is associated with

pancreatic insufficiency

increased serum lipase is associated with

pancreatitis

Increased serum AST (aspartate aminotransferase) is associated with

liver problems

Increased serum ALT (alanine aminotransferase) is associated with

liver damage

increased serum alkaline phosphatase is associated with

liver problems

decreased alkaline phosphatase is associated with

osteoporosis

What is a CMP

comprehensive metabolic panel

What is included in a CMP

everything on a BMP pluse AST ALT Alk phos Bilirubin total protein albumin

BMP includes (list)

Na K Cl HCO3 BUN Cr Glucose Ca

CMP includes (list)

Na K Cl HCO3 BUN Cr Glucose Ca ALT AST Alk phos Bilirubin total protein Ablumin

Serum GGT (gamma-glutamyl transferase) can test for

liver problems (not included in CMP/BMP)

Examples of POCT (point of care testing)

fingerstick glucose urine preg rapid strep Hgb A1c

Intro to Lab Medicine & Common Lab Tests Flashcards

(148 cards)