Download Introduction to the Principles of Laboratory Medicine

Introduction to the
Principles of Laboratory
Medicine
Module 1
What is laboratory medicine?
Case Scenario 1
O A 77-year old man presents to the emergency
department with fevers and chills. He has had
multiple urinary tract infections in the past and
feels that this is “another one”. He has a history
of diabetes mellitus, type 2 with diabetic
nephropathy and chronic kidney disease.
Physical exam is notable for an ill-appearing
man with right flank tenderness.
O How will the medical laboratory impact this
patient’s care?
Case Scenario 1
Discussion
O Confirm clinical diagnosis
O Urinalysis
O Guide appropriate dosing of antibiotics
O Dose adjustment for reduced GFR based on
variables including serum creatinine
O Guide selection of appropriate antibiotic
therapy
O With multiple course of treatment in the past
there may be issues with antibiotic resistance
Photo by Elizabeth Wantuch, MD
Call “the lab”….
O Today’s clinical laboratory is a complex
arena offering an expansive menu of tests
which continues to grow
O Hundreds of millions of laboratory tests are
performed every year in the United States
Influence of Laboratory Medicine on the
quality and cost of healthcare
O Lab tests consume about 2.3% of annual
health care costs in the United States
O It is noted in the literature that >70% of the
objective data in a patient’s medical record
comes from the clinical laboratory
WHAT is
“Laboratory Medicine”?
O Laboratory medicine (clinical pathology) is
the medical discipline that specializes in the
performance, reporting and interpretation of
clinical laboratory tests in the provision of
high quality patient care
WHO is
“Laboratory Medicine”
O Comprised of pathologists, doctoral-level
laboratory scientists, technologists, and
technicians
O The laboratory medicine workforce has a
vital role in the health care system
managing and applying evidence-based,
scientific testing techniques to support
patient care
The specific types of clinical
laboratories in health care
institutions varies greatly from one
place to another.
Listed below is a partial list of types of
individual clinical laboratories
Blood Bank/Apheresis
Chemistry/Immunoassay
Hematology and Coagulation
Urinalysis, Fluid Analysis and Medical Microscopy
Cytogenetics
Endocrinology
Immunoserology
Microbiology (including Bacteriology, Virology,
Parasitology, etc.)
O Molecular Pathology
O Tissue Typing/HLA
O Toxicology
O
O
O
O
O
O
O
O
O Each lab may have one medical director and
one technical specialist responsible for
testing services and quality of the lab
O Some labs require a combined leadership
group of 2-3 directors and multiple technical
specialists
Additional Terms
Photo by Theresa Kristopaitis, MD
“Reference lab”
O In our medical center the lab tests performed at
reference labs are often called “send out labs”
O Clinical reference laboratories provide testing
services for patients and healthcare providers
O The labs performed are generally specialized
tests that are infrequently ordered or that
require specialized equipment
“Point of Care Testing”
Photo by Theresa Kristopaitis, MD
Point of Care Testing (POCT) is laboratory
testing performed on simpler devices at the
point of care (e.g., the bedside) and often by
non-laboratory personnel
Case Scenario 2
O A 5-year old boy is at his physician’s office with fever,
sore throat and severe pain with swallowing x 2 days.
On physical exam his temperature is 390C. There is
tonsillar erythema and swelling with white exudates.
O What point of care test do you think was performed?
O A rapid Streptococcal antigen test
O The test is positive. How does this impact the care of
the patient?
O Appropriate antibiotics are prescribed
O What if the test were negative?
O The physician understands the sensitivity and
predictive value of the rapid antigen test. If the
clinical suspicion for Streptococcal pharyngitis is
high a throat culture would be submitted
Case Scenario 3
O A 5-year old boy is at his physician’s office with low
grade fevers, sore throat, runny nose, watery eyes for
the past week. On physical exam he is afebrile. There
is minimal tonsillar swelling and erythema without
exudates. The boy’s parents insist that he be treated
with antibiotics.
O The physician has a low clinical suspicion for
Streptococcal pharyngitis but does perform a POCT
Strep antigen screen. The result is negative. How
does this impact patient care?
O Support to not provide unnecessary antibiotic
therapy for what is likely a viral upper respiratory
tract infection
What is the Point
of “POCT”?
O The key objective of POCT is to produce a
result more quickly
O Therefore the utility of POCT is in the
immediacy of response and effect on
medical decision making
O Due to advances in technology, clinical
needs and a number of other factors, POCT
may be the most rapidly growing segment of
laboratory testing worldwide
What POCT is available for the
following patients?
O 24-year old woman with amenorrhea x 2
months?
O Urine HCG
O 42-year old man with diabetes mellitus?
O Glucose, HgbA1c, urine microalbumin
O 63-year old woman with atrial fibrillation on
warfarin
O INR
O 78-year old man presenting to the ED with
10/10 crushing chest pain
O Troponin
O Proceed to “Module 2: The Diagnostic
Testing Process”