CMP Flashcards
why do we order diagnostic tests
- establish diagnosis in a symptomatic patient
- screen for disease in asymptomatic patients
- assess the condition or prognosis of patient with an established disease
- monitor therapy administered to a patient
- confirm the absence of a given disease or condition
dangers of inappropriate testing
- increased time to correct diagnosis
- financial cost
- physical and emotional distress
- liability of following up on abnormal results
- risk of misdiagnosis or “red herrings”
- false negatives and positives
questions to ask when ordering a test
will this test:
1. be timely
2. be cost-effective
3. be sensitive and specific
4. put the patient at risk of undue harm
5. affect my management of patient
no test has ___% sensitivity
100
the greater the abnormality of the test result, ___
the more likely it is that the result represents a real disorder
critical values require ___
immediate clinical attention
reference ranges ___ between labs and facilities
vary
factors that affect test results
- age
- kids have difference reference ranges
- middle-aged and older have age-related changes in many labs - albumin, total protein, cholesterol, creatinine clearance, BNP - gender
- increase muscle mass and overall body mass in men
- diference in hormonal secretion - race
- genetic diseases
- may cause subtle differences in physiology and metabolism - medications
- can cause both false positives and false negatives - pregnancy
- endocrine, hematologic, metabolic, hormonal changes - food ingestion
- direct measurement of byproducts of food
- impact on metabolism - posture
- affects concentration of several components in peripheral blood
- NOR, EPI, renin, aldosterone, protein, potassium - timing
- natural physiological variation of hormones, other blood components throughout the day
- half-life medications and their metabolites
the set of values that 955 of the healthy population falls within for a particular testing parameter
reference range
reference range is ___%
95%
reference range varies between labs due to (4)
differences in methodology
testing equipment
reagents
units of measurement
predetermined set of individual tests, often related in some way, that are commonly ordered together
test panels/profiles
6 test panels
CBC
BMP
LFT
TFT
renal panel
anemia panel
advantages and disadvantages of single tests
advantages:
- specific to particular condition
- less risk of “red herrings”
- may be lower cost
- generally less test sample needed
disadvantages
- may miss associated abnormalities or complications from the primary disease
- may be more expensive than a commonly ordered panel
- may miss a diagnosis by looking at a single test
advantages and disadvantages of test panels
advantages
- allow labs to streamline performing large numbers of the same tests
- commonly ordered panels often have rapid turn-over
- may be less expensive
- gives more comprehensive overview of disease status
disadvantages
- may be sub-optimal tests
- more tests causes higher incidence of finding an abnormal that may have no clinical significance
