Intro to Clinical Chem Flashcards
What is clinical biochem composed of?
-The application of chemical/biochem methods in the study of disease
-Analysis of soluble non-cellular components of bodily fluid
-Broad repertoire of tests for a variety of clinical conditions
What is the biochem test repertoire composed of?
-Routine clinical biochemistry e.g liver, renal, cardiac, bone, glucose
-LiPIDS e.g Cholesterol, triglycerides, lipoproteins
-Endocrinology
Specific proteins
Therapeutic drugs
Cardiac markers
Toxicology
DNA/molecular diagnostics
What would be carried out in the general chemistry tests?
-U&E (renal panel) : Na, K, Cl, urea, creatinine
-Liver func tests (LFTs) : total protein, albumin, ALT, bilirubin
-Bone panel: Ca, albumin, Mg, P
-Lipids: cholesterol, HDL, LDL, triglycerides
-Glucose
-Arterial blood gas measurements - point of care testing
-CSF analyses: protein, glucose, xanthochromia
-Other misc. tests include: amylase, AST, GGT, ACE, bile acids, CRP, urate, ammonia
What will be tested for in toxicology?
-Alcohol, paracetamol, salicylate
What is tested for in tumour markers (TMs)?
-CEA (CRC), CA 19-9 (pancreatic adenocarcinoma), CA 15-3 (breast ca)
What does diagnosis mean?
-Establish underlying reason for the signs, symptoms and complaints
What does monitor mean?
Follow the course of condition or monitor blood concentrations of drugs
What does screen mean?
Detection of sub-clinical disease, or detection of conditions in the absence of signs or symptoms
-Population screen e.g newborn screening programs- 9 metabolic diseases screened at birth
-Screening based on risk e.g screening for colon cancer using faecal occult blood (FOC) testing – increasing age is an established risk for colon cancer
What does prognosis mean?
Establish risk and potential timeline for future events
Sign vs Symptom
Sign - something that is observed externally
Symptom - manifestation of disease perceived only by the person affected (subjective)
Examples of biochem sample types?
Blood (serum)
Urine, cerebrospinal fluid (CSF)
Stool, amniotic fluid, tissue specimen
What are factors that affect the choice of blood source?
-Analyte under investigation
-Vascular status of patient, ease of collection
Describe the fractionation/separation of blood and what is in each fraction?
- Upper phase: plasma or serum
-Clear often straw coloured fluid
-95% water, plasma proteins (albumin, globulin, fibrinogen), clotting factors, electrolytes, glucose, acute phase proteins, hormones, blood gases etc - Middle phase: buffy coat
-WBCs and platelets
-Usually white in colour - Lower phase: RBCs
-Dense
What can be seen in the fractionation of blood in a neutrophilia sample?
-Buffy coat has green discolouration
How is urobilin produced?
Bilirubin is broken down by microbes in the intestines, producing urobilinogen
This can then be absorbed into the bloodstream and oxidised to produce urobilin
Urobilin is excreted by the kidneys and gives urine is yellow xolour
Production of Haemoglobin? Why does blood turn brown?
Haemoglobin is a protein found in blood, built up of smaller subunits containing ‘haems’
These haems contain iron and their structures give rise to our blood and its red colour when oxygenated
As blood dries it gradually turns brown as haemoglobin is oxidised to methaemoglobin
Production and colpours of biliverdin and bilirubin?
Haem in old and damaged RBCs can be broken down, first into green pigment biliverdin, which itself is converted to the brown pigment bilirubin
Both are found in bile and can also cazse the colouration around bruises.
How is stercobilin produced?
Urobilinogen produced by the breakdown of bilirubin in the intestines can continue through the digestive system and be reduced to stercobilin
This is excreted from the body in the faeces and is responsibe for their brown colouration
What is TPN?
Total parental nutrition - a method of feeding that bypasses the GI tract
A special formula given through a vein (superior vena cava) provides most of the nutrients the body needs
Serum vs Plasma
Serum is the liquid that remains after the blood has clotted (recommended)
Plasma is the liquid that remains when clotting is prevented w the addition of an anticoagulant
What are examples of anticoagulants?
Heparin, EDTA (ethylenediaminetetraaceticacid), Oxalate/Fluoride
How does heparin work?
Its a glycosaminoglycan polymer
-Inhibits action of thrombin (Factor II) which an a natural anticoagulant
How does EDTA work?
Chelates divalent cations (including Ca2+ - required for coagulation cascade)
How does Oxalate/fluoride work?
Oxalate binds Ca2+, fluoride inhibits glycolysis, used preserve glucose concentration, if measuring glucose and its going to be a while before sample is tested and want glucose levels to remain as they were
