Unit 4 Part 1 - Clinical Chemistry Flashcards
study of chemical components of the body in plasma or serum
clinical chemistry
3 groups of clinical chemistry in the lab
- routine chemistry
- routine chemistry urinalysis
- special chemistry
types of specimens in chemistry
blood (serum or plasma) – not RBC except for HgbA1C
urine
feces
CSF
sweat
hair
stones
first department to be automated
chemistry
benefits of automation
reduced medical errors
reduced sample volume
improved safety
faster TAT
step 1 in automated analysis
make sure specimen is properly collected
step 2 in automated analysis
instrument is programed to measure proper amount of specimen and reagent to yield a final conc
most of the automation is based on
photometry
step 3 in automated analysis
chemical reaction causes sample to change color
part of the instrument that measures how much light will pass through the sample
spectrophotometer
a reaction that results in a dark color would allow __ light to pass through, which means __ result
less, higher
a reaction that results in a light color would allow __ light to pass through, which means __ result
more, lower
blood glucose will produce a __ color after chemical reaction with a reagent
blue
dark blue color indicates ___ glucose result
high
medium blue color indicates ___ glucose result
normal
light blue color indicates ___ glucose result
low
step 4 in automated analysis
instrument programmed to measure the absorbance and give result
step 5 in automated analysis
reading results and see if it falls within certain parameters
machines test hundreds - thousands of ___ per hour
tests NOT specimens (1 patient can have more than 1 test done)
testing in this department includes processes used to detect levels of enzymes, suagrs, proteins, and otehr substances in the blood in order to determine conditions
clinical chemistry
formed by hgb breakdown, increased in liver damage
bilirubin
end product of protein metabolism and is excreted by the kidneys, increased in kidney damage
urea
measures the lipids in the body
cholesterol & triglycerides
metabolic waste, increase indicates kidney damage
creatinine
determines the correct dosage of a drug
drug analysis
test for electrolyte imbalance
electrolytes
test for diabetes (FBS, 2 hr PC, 1 hr post load, GTT, HGB A1C)
glucose
simple sugar formed when dietary carbohydrates are digested, absorbed in digestive tract into blood
glucose
the liver removes excess glucose from the blood and stores it as
glycogen
liver converts glycogen back to glucose when glucose is needed for energy by the body cells
this process is called
glycogenolysis
tests to diagnose and monitor diabetes
random glucose
fasting blood sugar
2 hour PC
1 hour post load
OGTT, GTT
Hgb A1C
glucose test taken any time, no requirements
1 blood sample needed
random blood glucose
glucose test where patient fasts for 8-12 hours
nothing to eat or drink during that time, except water
1 blood sample needed
fasting blood sugar (FBS)
normal FBS
3.9-6.1 mmol/L
glucose test taken exactly 2 hours after a meal (usually 1000 hrs, or 1400 hrs)
patient instructed to have substantial meal with good amount of carbs
2 hour postprandial blood glucose test
normal 2-hr PC
3.6-8.8 mmol/L
screening type used for type 2 diabetes
fasting blood sugar
2 types of screening methods for diabetes
non-gestational oral glucose tolerance test (non-pregnancy)
gestational oral glucose tolerance test (pregnancy)
other tests are done to screen diabetes when fasting blood sugar is BETWEEN
6.1-6.9 mmol/L
capillary blood glucose cut-off point for OGTT (non-gestational) with glucometer
if higher than this, test cannot continue
10 mmol/L
when you don’t have a glucometer for OGTT (non-gestational) collect __ to determine glucose level
FBS level
glucose level cut off for OGTT (non-gestational) without glucometer
7 mmol/L
if patient vomits or becomes sick during OGTT, test is __
discontinued
___ and glucometer determines eligibility for administering oral glucose
capillary blood glucose
during OGTT (non-gestational), patient must finish the ___ glucose drink within 5 mins and sit still
75 gm
2 hours after the glucose drink has been consumed, a venous blood sample is collected and labeled ___
2 hr post load
why is lab glucose level cut off lower than glucometer?
glucometer not accurate due to interstitial fluid and other things mixed in with capillary blood
total blood specimens collected during OGTT (non-gestational), assuming test is done throughout, with and without glucometer
with glucometer: (2, excluding capillary)
1 capillary
1 venous FBS
1 venous 2 hr post load
without glucometer: (2)
1 venous FBS
1 venous 2 hr post load
it is recommended that all pregnant women should be screened for diabetes between __
24-28 weeks
screening for gestational diabetes mellitus is a ___ approach
2 step
1st step in screening for gestational diabetes mellitus (type 2)
50 gm glucose challenge with a blood glucose level taken after 1 hr
patient does not have to fast in 50 gm glucose challenge (t/f)
true
in the 50 gm glucose challenge, if the blood glucose level is ___ or greater (determined by glucometer), the test cannot continue
15 mmol/L
in the 1st step of the 50 gm glucose challenge, blood sample is collected __ after the drink has been consumed
1 hr
in the 1st step of the 50 gm glucose challenge, we proceed to step 2 if the glucose level is between ___
7.8-11.0 mmol/L
step 2 of the 50 gm glucose challenge is called the
OGTT
in OGTT (gestational), patient fasts for
8-16 hours
capillary blood glucose cut-off point for OGTT (gestational) with glucometer
if higher than this, test cannot continue
10 mmol/L
glucose level cut off for OGTT (gestational) without glucometer
11 mmol/L
in OGTT (gestational) the glucose drink give is ___ and must be finished within 5 mins
75 gm
total blood specimens collected during OGTT (gestational), assuming test is done throughout, with and without glucometer
with glucometer: (3, excluding capillary)
1 capillary blood
1 venous FBS
1 venous 1 hr after drink
1 venous 2 hrs after drink
without glucometer: (3)
1 FBS
1 venous 1 hr after drink
1 venous 2 hrs after drink
normal values for GTT
fasting: 3.9-6.1 mmol/L
1 hour: 8.8-9.4 mmol/L
2 hours: less than or equal to 6.6 mmol/L
3 hours: 3.9-6.1 mmol/L
- goes down as time passes
test used to determine the average blood glucose level in a patient over a 2-3 month period
Hgb A1C
tube used for Hgb A1C
purple EDTA, need whole blood
normal Hgb A1C
4.4-6.4%
Hgb A1C is sent to ___ department, but is collected in __ tubes
chemistry, purple
4 common electrolytes
sodium (Na)
potassium (K)
chloride (Cl)
carbon dioxide (CO2)
electrolyte responsible for the normal distribution of water between extracellular and intracellular compartments and also functions in transmission of nerve impulses
sodium (Na)
electrolyte that functions in muscle contractions, and conduction of nervous impulses, important for the heart
potassium (K)
electrolyte that functions to maintain water balance, along with sodium
chloride (Cl)
electrolyte that maintains the acid-base balance of the body
increase of this would lower pH of blood
carbon dioxide (CO2)
tube used to collect electrolytes
lithium heparin (green)
concentration of K in RBC is about ___ times that in serum or plasma
20
examples of other electrolytes
calcium, magnesium
tests used for renal function
urea
creatinine
uric acid
creatinine clearance (requires 24-hr urine and blood specimen)
act as hormones or hormone precursors
energy storage and metabolic fuel
structural and functional component in cell membrane
insulation to allow conduction of nerve impulses or heat loss
lipids
there is a correlation between lipids and ____ (which can lead to coronary heart disease)
atherosclerosis
tests used for lipids
cholesterol
triglycerides
low density lipoprotein (LPL)
high density lipoprotein (HDL)
3 chemistry tests used to diagnose a myocardial infarction or injury (heart attack)
troponin
myoglobin
creatine kinase myoglobin (CK-MB)
heme protein found in striated skeletal muscle cells and cardiac muscle
early marker of injury to muscle tissue
rise in concentration can be detected in blood as early as 1-3 hours after the onset of MI symptoms
myoglobin (MB)
gold standard of cardiac markers
complex of 3 proteins found in cardiac or skeletal muscle
remain elevated in blood for 4-10 days after MI
troponins
complex of 3 proteins for troponins
troponin T (TnT)
troponin I (TnI)
troponin C (Tnc)
can be elevated after tissue injury
cardio specific and is sensitive to early onset of MI
elevation can be seen within 4-6 hours of onset symptoms
creatine kinase myoglobin (CK-MB)
alkaline phosphatase (Alk phos)
bone, liver
gamma glutamyl transferase (GGT)
liver
alanine transaminase (ALT)
heart, liver
aspartate transaminase (AST)
heart, liver
lactic dehydrogenase (LD)
liver, heart, muscle
liver tests
ammonia
bilirubin
alk phos
GGT
ALT
AST
LD
accelerate many metabolic reactions in the body, higher number means more damage to organ
usually end in “ase”
enzymes
lipase (LPS)
pancreas
pancreatic testing involves
lipase
isoamylase
a chemical substance produced by a gland in one part of the body and carried to a distant target organ where a regulatory response is elicited
hormones
thyroid tests
T3
T4
TSH
most prevalent type of protein
albumin
albumin is about ___ of total protein in our bodies
2/3
other types of proteins are in a class called
globulins
types of globulins
alpha 1 globulins
alpha 2 globulins
beta globulins
gamma globulins (most are antibodies)
5 groups of gamma globulins
IgA - respiratory, gut, skin, renal infections
IgD - chronic bacterial infections
IgG - autoimmune responses, response after subsequent exposure to an Ag
IgE - asthma, allergic conditions
IgM - viral infections, blood stream infections, first response after exposure to Ag
separates serum into 5 fractions, done in immunology
protein electrophoresis
TDM
therapeutic drug monitoring
helps manage patients being treated with certain drugs in order to establish a drug dosage and avoid toxicity
therapeutic drug monitoring
2 parts to TDM
trough
peak
taken before drug is given
trough level
usually taken:
- 30 mins after IV administration
- 60 minutes after intramuscular injection
- 2 hrs after oral intake
peak levels
examples of drugs for TDM
digoxin
theophylline
vancomycin
phenytoin
trace metals are collected in
royal blue EDTA tubes
can’t collect trace metals with
syringe
capillary methods
trace metals include
aluminum
arsenic
cadmium
chromium
copper
lead
manganese
mercury
selenium
thallium
zinc
most common trace metals
copper
lead
zinc
testing done at patient’s bed side or ancillary bedside, or near patient testing (instead of lab)
point of care testing (POCT)
device used to test blood sugar, commonly used by diabetics to monitor their blood sugar on a daily basis
example of POCT that does one test
glucometer
most sources of POCT error
pre-analytical errors
operator incompetence
nonadherance to test procedures
use of uncontrolled reagents and equipment (expired or not tested properly)
POCT is more expensive than central laboratory testing (t/f)
true
an example of multiple test POC machine
depends on program or cartridge that is used
some include glucose, cholesterol, electrolytes, enzyme analysis, cardiac markers, hemoglobin, hematocrit, and INR
i-STAT
performed as per manufacturer guidelines
usually involves performing liquid quality control on receipt of new shipment of kits and teaching new personnel
external quality control
quality control where liquid is of a known result
liquid is applied to POCT instead of blood or other fluid
result should be exactly what known result is
liquid quality control
means that the instrument can detect clotting, short samples, air bubbles, etc
electronic QC’s
prevents users who are not authorized or do not adhere to QC procedures from using machine
automatic lockout feature
when using glucometers, the ___ drop of blood is wiped away
first
another example of POCT
usually requires a first morning urine specimen (highest concentration of hCG hormone)
must be colelcted in clean plastic container
can be refrigerated for up to 2 days, or frozen at -20 C for 1 year
pregnancy test
POCT instruments usually found in the ICU or ER, can measure multiple tests
multiple-test-panels by POCT
breakdown of red blood cells
hemolysis
test result most affected by hemolysis
potassium (K)
slight increase in results due to hemolysis
phosphate
tota protein
albumin
calcium
alk phos
slight decrease in results due to hemolysis
haptoglobin
bilirubin
moderate increase in results due to hemoplysis
ALT
CK
iron
moderate decrease in results due to hemolysis
T4
gross increase in results due to hemolysis
K
LD
AST
gross decrease in results due to hemolysis
troponin
glucose
