What is clinical laboratory science?
- the diagnostic testing of samples from human beings
- blood, urine, feces, secretions, serous fluids, spinal fluid, seminal fluid, stones, skin, nail, hair, bone, tissue
- imperfect because humans are involved
What are the purposes of a lab test?
- Detect a disease: establish/confirm a diagnosis, reduce a differential
- Guide disease treatment
- Monitor disease progression est prognosis/response to Tx
- Health maintenance
- Not to be done in isolation or used as a “static automatic”
What are the classifications of diagnostic tests?
- Invasive vs Noninvasive: instrument entering body
- Disciplines: specific to hematology, transfusion, chemical, immunology, microbiology, microscopy
- Results: qualitative, quantitative (#), semiquantitative (degrees)
- Screening vs. Diagnostic: asymptomatic vs symptomatic
What is precision, accuracy, reference range, critical value?
- Precision: close together
- Accuracy: close to target
- Reference range: statistically derived numerical range from a sample of individuals assumed to be normal (2SD)
– influenced by lab issues, physiologic variation, sample assumptions, new information, more sensitive tests - Critical (panic) value: impending morbidity outside of range lab must communicate with provider, should correlate to pt presentation
What is a profile or panel test?
- A series of related tests
- Less thinking and cost up front
- More information to interpret
ie - Basic Metabolic Profile (BMP): electrolytes, CO2, BUN, Ca, Cr, Glucose
- Comprehensive Metabolic Profile (CMP): BMP + albumin, ALT, AST, TBili, Tpro
- Renal Panel, Liver Panel
What is sensitivity?
- Identifying true positives
- Want in screening
- SNOUT (sensitivity rules out) if negative
- True positives divided by true positives and false negatives
What is specificity?
- Identify true negatives
- Want for diagnostic
- SPIN specificity rules in (if positive), confirm diagnosis
- True negative divided by true negatives and false positives
What is predictive value?
- From a test’s sensitivity, specificity, and disease prevalence
- Tests reliability
- Equal sensitivity and specificity PV increases with incidence
What is pre-test probability?
- likelihood that a patient has the disease before the test affects the value of the test in making clinical decision
What is the ideal test?
- 100% sensitive, specific, accurate, precise, pain free, risk free, inexpensive, useful
- not exist
- instead: expert guidelines A-D
What is the healthcare provider’s role in testing?
- Communication
- Protocols
- Pt independence/autonomy
- Ethical/legal implications
- Cultural sensitivity
How do you obtain worthwhile data ?
Quality assurance
- Policies and procedures to ensure accuracy and reliability
- Personnel
- Instrument calibration
- Specimen collection: preparation, procedure, container & preservatives, labeling, storage/transport
Error
- Systematic (calibration/reagents)
- Human error: reading results, technique, specimen handling/preparation
- Random: slight variation in natural measurement
What should be considered with lab interpretation?
- Test value cannot be interpreted in isolation
- Treat the patient not the result
- Trends may be more important than values
- Pt-related factors: age, organ function, time course, DNA, biologic rhythms, drugs, died, fluid status, posture & altitude
What are the expert guidelines for grading tests?
- Grade A: clear consistent evidence from high-quality conducted trials
- Grade B: Supportive evidence from several studies or registries that may have limitations
- Grade C: No published evidence or only case, observational, or historical evidence with limitations
- Grade D: expert consensus or clinical experience or internet polls, no direct research evidence
What is the purpose of standard precautions?
To protect the provider and patient from infectious agents in blood, body fluids, secretions, excretions except sweat, non-intact skin, mucous membranes
What are the key recommendations of the CDC for Standard Precautions?
- Hand hygiene: alcohol-based unless visibly soiled or caring for pt w/ infectious diarrhea & exposure to pores then soap & water
- Use of PPE: gloves, respirator/mask, goggles/shield, gown
- Respiratory hygiene/cough etiquette: cover, dispose tissues immediately, hand hygiene, masks, sit far away, educate
- Sharps safety: prepare (organize, well-lit, training, assess hazards), aware (in view, ppl around, X rush/distract, focus, avoid hand-passing use words, watch), dispose (you use, activate safety features, dispose, keep fingers away from sharps containers)
- Safe injection practices: aseptic technique, med diaphragm w/ alcohol, one syringe/pt/one time access, one infusion set/pet, single-dose/use to one pt, multidose - one pt
- Sterile instruments and devices: self-sheathing needles, needleless, disposing at point of use
- Clean & disinfected environmental surfaces: routinely used –> disinfect, reusable clean & disinfect
What are common bloodborne pathogens and how are they spread?
- Hepatitis B
- Hepatitis C
- HIV
What can prevent contact with bloodborne pathogens as a PA-s and clinician?
- following standard precautions
- minimizing exposure
What are appropriate steps after unprotected contact with blood or body fluids?
- First aid: wash, flush, irrigate
- Report:
- Seek Medical care
What are the components, indications, contraindications, limitations, advantages, disadvantages, relative costs, risks, potential complications, and patient preparation, education, and follow up for a basic metabolic panel?
- Components:
– electrolytes: Na, K, Cl, HCO3/CO2, Ca
– kidney: BUN, Creatinine, Glucose - Indications: metabolism, kidney function, fluid and electrolyte balance, blood sugar levels, acid base balance (gives picture of pt)
- Contraindications: pt cannot have venipuncture (fistula, mammectomy)
- Advantages: lots of information
- Disadvantages: too much information, some hospitals not take panels
- Relative costs: varies ($11-79)
- Risks: associated with venipuncture
- Complications: associated with venipuncture
- Pt Preparation: venipuncture procedure - glucose may require fasting/continue meds
- Pt education: explain venipuncture procedure
- Pt follow up: to discuss results if significant
What are the important aspects of a sodium blood test?
Adult: 136-145 mEq/L
- Critical values
– 90-105 Hyponatremia: neurologic dysfunction
– >160 Hypernatremia: heart failure (reatain water)
- Clinical implications
– Hyponatremia: burns, CHF, fluid loss, malabsorption, diabetic acidosis, H2O intoxication, hypothyroidism
– Hypernatremia: dehydration, Cushing disease, OTTANVC
- Interfering factors
– Drugs dec/inc
– high triglycerides/low protein artificially low values
What are the important aspects of a potassium blood test?
Adult: 3.5-5.2 mEq/L
Cardiac problems
- Critical values:
– Hypokalemia: <2.5mEq/L VF
– Hyperkalemia: >8.0meq/L muscle irritability
- Clinical implications
– Hypokalemia: Diarrhea, vomiting, sweating, starvation, malabsorption, CF, alcoholism
– Hyperkalemia: Kidney disease, uncontrolled diabetes
- Interfering Factors
– Hemolysis
– drugs
– (licorice)
- Clinical: those getting IV fluids need daily K+
What are the important aspects of a chloride blood test?
Adult 96-106 mEq/L
- Critical: <70 >120 mEq/L
– Least important electrolyte, doesn’t do much and varies easily
- Clinical implications
– Decreased: severe vomiting, HF, gastric suction
– Increased: dehydration, hyperventilation, severe kidney disorders
- Interfering factors
– Infants > adults & children
– Drugs
– Excessive IV saline
What are the aspects of a blood urea nitrogen test?
Adult: 6-20mg/dL
- Urea formed liver breakdown protein removed kidneys, indicate GFR
- Critical: >100mg/dL
- Clinical implications
– Inc: impaired kidney function, chronic kidney disease, excessive protein intake/breakdown,
– dec: liver failure, malnutrition
- Interfering factors
– Diet: low protein, high carb
– Lower women & children (muscle mass)
– late pregnancy
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Module 1a: Intro, BMP, CMP36
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Module 1b: CBC, UA, Derm48
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Module 2: Radiology & Neuroimaging/diagnostics122
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Module 3: Musculoskeletal73
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Module I: Behavioral48
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Module 2a: Cardiac Labs28
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Module 2b: Electrocardiogram63
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Module 2c: Electrocardiogram54
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Module 2d: Cardiopulmonary Imaging & Advanced Cardiac Evaluation89
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Module 3: Endocrinology, Pulmonology139
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Module 1: EENT & Abdominal Imaging77
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Module 2: GI Imaging & Labs109
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Module 3: GU & Renal67
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Module 4: Electrolytes & Fluids40
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Module 5: Hematology & ID35
