M103 T3 L8 Flashcards
What percentage of clinical decisions are informed by data from Laboratory Medicine?
70%
Why are lab tests requested?
when screening for disease when looking for risk stratification when diagnosing a disease when looking for a prognosis when monitoring the progression / remission of disease when monitoring therapy therapeutic drug monitoring when looking for side effects of treatment
What is the focus of Therapeutic drug monitoring?
to analyse the measurements of medication levels in blood
What are the four main divisions of pathology?
Histology and Cytology
Bacteriology and Virology
Haematology
Biochemistry and Immunology
What types of tissue diagnosis can be found when analysing Histology and Cytology? (MIA)
malignancy, infection, auto-immune
What causes of infection can be found when analysing Bacteriology and Virology?
culture, antigen and antibody testing
increasingly PCR
Antibiotic use, public health, environmental testing
What haematologies can be found when analysing blood pathology?
Diseases of the blood
Transfusion
Coagulation
What substances can analytes be measured from when analysing bBiochemistry and Immunology?
blood, urine, CSF
What substances are analysed in Clinical Chemistry?
Serum, CSF Whole blood Urine, Faeces, Sweat Renal stones Post-mortem samples Miscellaneous fluids
What substances are tested for in clincial chemistry?
Ions, Metabolites Waste products, Drugs Markers of cell damage Functional enzymes, ATBYs Vitamins, Metals Plasma proteins Antibodies, Hormones
What are examples of metabolites that are tested for in clincial chemistry? (GALA)
glucose, amacs, lactate, lipids
What are examples of waste products that are tested for in clincial chemistry? (CUBU)
creatinine, urea, bilirubin, uric acid
What are examples of plasma proteins that are tested for in clincial chemistry?
lbumin, immunoglobulins, binding globulins, specific proteins
What types of drugs are tested for in clincial chemistry?
therapeutic monitoring, toxicology
What types of metals are tested for in clincial chemistry?
trace metals, toxins
What substances are tested for when testing renal function?
Na+, K+
urea, creatinine
What substances are tested for when testing liver function? (TAB.APAT)
total protein, albumin, bilirubin
alkaline phosphatase, alanine transaminase
What substances are tested for when testing bone profile? (TAC.APP)
total protein, albumin, calcium, alkaline phosphatase, phosphate
What substances are tested for when testing thyroid function?
TSH (free T4, free T3)
What substances are tested for when testing lipid profile?
total cholesterol, HDL-cholesterol, non-HDL
cholesterol, triglycerides
How are reference ranges generated?
take a large number of healthy individuals
measure the substance of interest
calculate the mean and standard deviation of the results
the reference range is [ “the mean - 2sd” - “the mean + 2sd” ]
What percentage of population results are within the reference range?
95% of results (for the population)
What percentage of population results are lower and higher than the reference range?
2.5% of results (for the population) for both lower and higher than the reference range
Do results outside the reference range imply disease?
not necessarily – they may be a chance finding in a healthy individual.
the more extreme the value the more likely that an abnormality / disease is present
Do results inside the reference range imply disease?
they don’t necessarily exclude disease
What are two examples of substances that vary between genders?
testosterone
creatinine
What is the purpose of measuring Creatinine levels?
to see how well the kidneys are functioning
What do Creatinine levels vary with?
age and sex
Why does creatinine vary with gender?
bc creatinine is produced by muscle and generally men have more muscle than women
Why does creatinine vary with age?
bc muscle mass increases with age
Why is it important not to just look at flagged results (outside the reference ranges)?
bc results can be outside the reference range in the absence of disease
results can be within the reference range when disease is present
If it’s important not to just look at flagged results, how should results be used?
by finding patterns in the results to associate with specific conditions
by comparing current and previous results for significant differences in specific levels
When are blood samples for an initial screen best collected at?
9am
Why is the drug dexamethasone?
to suppress cortisol
In what two conditions can alkaline phosphatase levels be elevated in?
in both liver disease and bone disease
When are gGT levels measured?
when alkaline phosphatase levels are elevated and the diagnosis needs to be differentiated between either liver disease or bone disease
When do elevated gGT levels indicate?
liver disease
What does a change in creatinine of >26 umol/L indicate?
that acute kidney injury may be a possibility
