Introduction to Biochemistry Flashcards
Why/how do you use biochemistry?
- used to evaluate different organ systems (liver, kidney etc.)
- measure enzymes/metabolites, electrolytes etc
- use with urinalysis and CBC
- in most cases serum is recommended but can use plasma for some tests
- anticoagulant in plasma can interfere with some tests
- use heparinised plasma for birds and reptiles due to small sample size
What is the difference between serum and plasma?
- PLASMA contains all CFs including fibrinogen. From blood collected into EDTA (haematology), heparin or citrate. Blood will not clot so need to separate plasma from cells by centrifugation. Store at 4 degrees.
- SERUM is the fluid part of the blood after clot formation. Collect blood into tubes without anticoagulant. Serum tubes have a red or brown top. Serum separator tubes with layer of gel which separates serum from cells. Allow blood to clot and remove supernatant (serum), centrifuge, serum separator tubes (gel), separate immediately if possible, store at 4 degrees.
What is looked at in a biochemistry profile?
Total protein, albumin, globulin, Bicarbonate anion gap calcium phosphorus glucose electrolytes - Na, K, Cl urea nitrogen creatinine bilirubin cholesterol amylase lipase CK ALT ALP SDH (large animals) GLDH (small animals)
How do you measure total protein?
Serum or plasma (these are slightly greater and fibrinogen is included). Made of albumin and globulins.
Measure by refractometer or colorimetric method.
What do increased and decreased protein indicate? (3 each).
INCREASED: dehydration, inflammation, neoplasia
DECREASED: loss (kidney, GIT), decreased synthesis, dilution.
FALSELY INCREASED: icterus, severe hemolysis and lipaemia.
How do you measure albumin? What do increased (1) and decreased (3) levels suggest?
HOW: dye binding method. Unreliable in birds - use electrophoresis.
INCREASED: dehydration
DECREASED: increased loss (renal, haemorrhage, GIT), decreased synthesis (liver), third spacing (effusions)
How do you measure globulins? What types are there? What do increased globulins indicate? (2)
HOW: calculated (total protein-albumin=globulin)
TYPES: gamma, beta etc. Separated by electrophoresis (not routine but if looking for a specific anomlay)
INCREASE: inflammation e.g. FIP (polyclonal), neoplasia e.g plasma cell tumour (monoclonal)
How do you evaluate the liver? (3)
enzymes, metabolites, function tests
How do you evaluate the pancreas? (2)
Amylase and lipase (but from other sources too so not specific)
INCREASES: dogs with pancreatitis (4-5 times, not cats), renal insufficiency
How do you evaluate the urinary system?
Look at BOTH serum/plasma chemistry and urine collected at the same time.
Urea and creatininte both indicate glomerular filtration.
Define azotemia. Causes? (3) Diagnosis?
=Increases in nitrogenous wastes (urea and/or creatinine) in the circulation
- CAUSES: pre-renal (dehydration), renal (renal disease), post-renal (obstruction)
- DIAGNOSE: check USG (ability of kidneys to concentrate urine), compare with serum/plasma urea and creatinine. If both of urea and creatinine are increased, USG should be at least 1.030 (dog), 1.035 (cat) and 1.025 (horse/ruminant)/ If USG is less then there is decreased concentrating ability and renal failure is present.
How do you investigate renal disease in ruminants?
Use creatinine only (urea is not a reliable indicator)
What are urea levels influenced by (2)?
Protein intake (e.g. high protein meal) or GI bleeding.
Why do sodium levels change?
Main ECF ion. Along with water, levels are regulated by kidneys (the only ion to be linked so closely to water)
INCREASED: increased intake, increased water loss or decreased water intake
DECREASED: increased loss or increased water intake.
Why do potassium levels change?
Main ion in intracellular space.
Levels affected by: acid-base chages, intake, renal function.
INCREASES: renal failure, hypoadrenocrticism, leakage from cells (tissue damage, thrombocytosis/leukaemia)
DECREASES: loss (renal, vomitting, diarrhoea), decreased intake
