Intro to Biochem Flashcards
List 5 clinical pathology tests
Hematology (CBC) Clotting profile Biochemistry Urinalysis Cytology
What is biochemistry used for?
Evaluate different organ systems
Measure enzymes, metabolites etc.
Use with urinalysis and CBC
What fraction of blood is evaluated for buichemistry?
Serum (lacking clotting factors but means nothing is added to tube) vs. plasma which would have clotting factors (inc fibrinogen)
When may plasma be used?
Heparinized plasma used for reptiles and birds due to small sample size
What colour are serum tubes?
Red or brown
What additional chemicals may be added to serum tubes
Serum separator separates cells from serum to prevent RBCs metabolising glucose etc. affecting serum levels
What is another term for serum?
Supernatent
How should serum be stored?
4 degrees c
How is plasma collected?
Into EDTA, Heparin or citrate tubes
Separate plasma from cells by centrifuge
Store at 4 deg C
What does within reference interval (WRI) mean?
95% animals will be within the range when healthy
If multiple parameters assessed ^ chance of finding an out of range result.
What are blood levels of analytes dependent on?
Amount produced and amount excreted.
Remember if ^ production and concurrent ^ excretion, values will appear within normal range
Where is total protein measured from?
Serum or plasma
Which value of total protein will be higher (serum v plasma)?
Plasma greater as includes fibrinogen
What does total protein consist of?
Albumin and globulins
How may total protein be measured? How does this mean results may be affected?
Refractometer (in clinic) or colorimeter (in lab)
Results may be falsely raised by icterus, hemolysis and lipemia
When may increased total protein be seen?
Dehydration
Inflammation
Neoplasia
When may decreased total protein be seen?
Loss (nephropathy or enteropathy)
Decreased synthesis
Dilution
How is albumin measured? In which species is this unrelable and how is this overcome?
Dye binding method
Unreliable in birds - use electrophoresis instead
When is increased albumin seen?
Dehydration
When is decreased albumin seen?
Loss (renal, hemorrhage, GI) v synthesis (liver) 3rd spacing (effusions)
How is globulin concentration calculated?
Total protein - albumen
Globulins = all remaining proteins
How would individual globulins be separated and what may this show?
Electrophoresis
If polyclonal shows inflamation (eg. FIP)
If monoclonal shows neoplasia (eg. plasma cell tumour)
What 3 things are evaluated when looking at the liver?
Enzymes
Metabolites
Function tests
What 2 enzymes, detectable in the blood, does the pancreas secrete most of? Are they pancreas specific?
Amylase and lipase
Not pancreas specific - can come from other sources
When are increases in amylase and lipase seen?
Renal insufficiency
Pancreatitis - 4/5 fold increase in dogs, NOT cats
Which two analyses must be carried out to evaluate urinary system function?
Serum/plasma chemistry and urine
What are urea and creatinine indicators of? What else may they be associated with?
Glomerular filtration
Urea produced by liver so reflects liver function too
Creatinine produced in muscle breakdown (recumbency and IM injections can ^)
What is azotemia and what are the possible causes?
^ urea and creatinine in circulation Causes - pre-renal: dehydration - renal: renal disease - post renal: obstruction
How may the cause of azotemia be diagnosed?
Check urine specific gravity - measure of kidneys ability to concentrate urine
If USG low, renal funciton is impaired
If USG normal, dehydration is the cause
If urea and creatinine are increased in the serum/plasma, what should USG be in horse, cat and horse/ruminant?
- 030 dog (1.010 would indicate imparied renal function)
- 035 cat
- 025 horse/ruminant
In which species is urea not a reliable indicator of renal disease? Why?
Ruminants - use creatinine only
Urea can be excreted into saliva and digested by rumenal microbes, so blood levels may be normal despite impaired renal function
What are urea levels influenced by?
Protein intake - high protein meal OR GI bleeding
What is the main ion in the ECF?
Sodium
What regulates sodium levels? Which other substance follows this?
Kidney
Water balance intrinsically linked
How may hypernatraemia occour? Hypo?
Hyper- ^ intake Na ^ water loss v water intake Hypo - ^ loss ^ water intake
In what paradoxical situations may sodium levels be unuseful in analysing biochemistry of the body?
Na levels always relative to water
SO
HypERnatraemia can result from LOSS of Na IF loss of water is GREATER
Hyponatreamia can result from NORMAL Na levels with increased water intake
etc.
Na only ion that behaves in this way
Where is the majority of potassium found? What will affect K+ levels?
Intracellular space
Acid/base balance (Inorganic acidosis -> H+ secretion to cells -> K+ ejected into blood stream to balance charges; alkalosis due to H+ loss draws H+ from cells -> K+ taken up by cells to balance charges; Alkalosis due to K+ loss -> H+ taken into cells out of blood stream), intake and renal function all affect levels
What does increased K+ indicate?
Renal failure
Hypoadrenocorticism
Muscle/tissue damage allowing leakage eg. leukaemia, rhadomyolysis
What does decreased K+ indicate?
Loss (renal/VD) or decreased intake
Must shift of parameters always be outside of references ranges to be abnormal?
No, relative to previous concentrations ie. if start extremely low and progress to normal, have actually increased massively
What do changes in Cl- usually coincide with?
Changes in Na
When are changes in Cl- without changes in Na+ seen?
Acid base balance issues
Vomiting/abomasal displacment
What may affect recorded levels of Cl-?
Other halides (test is non-specific) eg. if treating seizures with Bromide
Why is total calcium usually measured? Which fraction of calcium is actually relevant?
Its cheap!
Free calcium is the active form
What is calcium bound to? How can this be accounted for when total calcium levels are interpretted?
Albumin
If albumen decreased, bound Ca levels will be decreased and vice versa. So if total calcium high with low albumen, majority of Ca will be free.
Always look at Ca levels in conjunction with albumen
(NB. if increased then would further test free calcium to confirm)
What are caclium levels regulated by?
PTH and calcitonin
Which other ion is regulated by PTH and calcitonin?
Phosphorus
What are increases in phosphorus usually associated with?
Renal disease Young animals (growing) along with elevated Calcium and ALP *reference ranges are for adult animals*
How may renal damage be compensated for? What does this mean for path diagnostics?
PTH ^ can compensate Phosporus, Vit D and Calcium levels until complete renal failure is imminent
What is assessed in a urinalysis?
Gross appearance
Chemical analysis - SG, Urine strip
Sediment analysis - Cells, crystals, casts
