Intro to Biochem Flashcards by Jamie Byrne

List 5 clinical pathology tests

Hematology (CBC)
Clotting profile
Biochemistry 
Urinalysis
Cytology

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What is biochemistry used for?

Evaluate different organ systems
Measure enzymes, metabolites etc.
Use with urinalysis and CBC

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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)

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When may plasma be used?

Heparinized plasma used for reptiles and birds due to small sample size

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What colour are serum tubes?

Red or brown

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What additional chemicals may be added to serum tubes

Serum separator separates cells from serum to prevent RBCs metabolising glucose etc. affecting serum levels

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What is another term for serum?

Supernatent

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How should serum be stored?

4 degrees c

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How is plasma collected?

Into EDTA, Heparin or citrate tubes
Separate plasma from cells by centrifuge
Store at 4 deg C

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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.

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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

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Where is total protein measured from?

Serum or plasma

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Which value of total protein will be higher (serum v plasma)?

Plasma greater as includes fibrinogen

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What does total protein consist of?

Albumin and globulins

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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

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When may increased total protein be seen?

Dehydration
Inflammation
Neoplasia

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When may decreased total protein be seen?

Loss (nephropathy or enteropathy)
Decreased synthesis
Dilution

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How is albumin measured? In which species is this unrelable and how is this overcome?

Dye binding method

Unreliable in birds - use electrophoresis instead

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When is increased albumin seen?

Dehydration

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When is decreased albumin seen?

Loss (renal, hemorrhage, GI)
v synthesis (liver) 
3rd spacing (effusions)

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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?

1. 030 dog (1.010 would indicate imparied renal function) 1. 035 cat 1. 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