Theme 3: Lecture 8 - Reference ranges Flashcards
What are the purposes of lab test requests (6)
- Screening for disease
- Risk stratification
- Diagnosis of disease
- Prognosis
- Monitoring Progression/Remission of disease
- Monitoring Therapy (Therapeutic drugs, Side effects of treatment)
What types of samples do labs analyse (9)
- Serum
- Whole blood
- Urine
- Faeces
- Sweat
- Cerebrospinal fluid
- Renal stones
- Post-mortem samples
- Miscellaneous fluids
What needs to be measured in samples (11)
- Ions
- Metabolites
- Waste/breakdown products
- Markers of cell damage (enzymes, Trop T)
- Enzymes
- Plasma proteins
- Antibodies
- Hormones
- Drugs
- Vitamins
- Metals
What are the groups that tests are usually divided into
- Renal function
- Liver function
- Bone profile
- Thyroid function
- Lipid profile
What’s measured in a renal function test
sodium, potassium, urea, creatinine
What is measured in a liver function test
total protein, albumin, bilirubin, alkaline phosphatase, alanine transaminase
What is measured in a bone profile test
total protein, albumin, calcium, phosphate, alkaline phosphatase
What’s measured in a thyroid function test
TSH (T3 and T4)
What is measured in a lipid profile test
total cholesterol, HDL-cholesterol, non-HDL cholesterol, triglycerides
What % of healthy people have a result that will be flagged outside of the reference range
5%
Interpreting reference ranges
- Results outside the reference range don’t necessarily imply disease
- Results inside the reference range don’t necessarily exclude disease
Why can there be more than one reference range for something
What is normal will differ depending on age, sex, pregnancy ect
Describe the control of thyroid hormones
- Hypothalamus releases thyrotropin releasing hormone (TRH)
- This stimulates the pituitary to release thyroid stimulating hormone (TSH)
- This stimulates the thyroid to release T3 and T4 hormones which go to the peripheral tissues
- T3 and T4 also inhibit the hypothalamus releasing TRH and the pituitary releasing TSH
What is a hypothyroid pattern of results
- Increase in TSH
- Decrease in free T4
What is a hyperthyroid pattern of results
- Decrease in TSH
- Increase in free T4
