4. Metabolic disorders Flashcards
(41 cards)
What is average total protein concentration in blood?
60-80 g/l
What test is most commonly used to measure total protein blood concentration?
Biuret test
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Best detection range for this test is 20-100 g/l
Biuret test
Used to chromatographically measure total protein concentration in blood.
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Schematic chemical reaction: CO-NH + Cu++ + alkaline = purple colour complex
What are protein fraction of total blood protein?
- albumin
- globulin
- fibrinogen
What are the methods to measure albumin concentration?
- Spectrophotometry (bromocresol green as reagent)
- Serum electrophoresis (more expensive than spectrophotometry but is used when protein fraction analysis is the basic aim). This method provides albumin as % of the total protein so it;s necessary to know TP concentration
What is the only reason for increased blood albumin concentration?
Dehydration
What are the reasons for decreased albumin blood concentration?
- decreased intake of proteins, decreased absorption
- decreased synthesis - liver failure, acute inflammation
- increased utilisation - physiologic conditions cause mild changes: pregnancy, exercise, production (milk, eggs etc) and chronic diseases: chronic inflammation, neoplasm
- increased loss:
- via kidneys (protein losing nephropathy - PLN)
- GIT (protein losing enteropathy - PLE)
- skin (burn)
- sequestration to the body cavities
What are methods to measure globulins?
- Calculated as TP - albumin
- Serum electrophoresis
In what 5 fractions proteins are separated during electrophoresis?
- Albumin
- Alpha-1-globulins
- Alpha-2-globulins
- Beta globulins
- Gamma globulins
What are percentages of protein fractions for plasma and serum?
Plasma contains 50% albumin, 30% globulin and 20% fibrinogen
Serum contains 60% albumin, 40% globulin
Polyclonal gammopathy. Causes
Broad-based peak in the beta or gamma region
Causes: chronic inflammatory diseases, liver disease, FIP, heart worm disease, Ehrlichiosis
Beta-gamma bridging occurs in disorders with increased IgA and IgM such as lymphoma, heart worm disease and chronic active hepatitis
Monoclonal gammopathy
Seen as sharp spike in the beta or gamma region. Peak can be compared to albumin one.
Both non-neoplastic and neoplastic disorders can cause monoclonal gammopathy
What is the most common cause of monoclonal gammopathy?
Multiple myeloma (producing IgG or IgA monoclonal)
Neoplastic causes of monoclonal gammopathy
- multiple myeloma (IgG or IgA)
- lymphoma (IgM or IgG)
- chronic lymphocytic leukaemia (usually IgG)
- extramedullary plasmacytomas
- Waldenstrom’s macroglobilinemia (neoplasm of B-cells)
Non-neoplastic causes of monoclonal gammopathy
Kinda rare
- occult heart worm disease
- FIPV (rarely)
- Ehrlichia canis
- lymphoplasmacytiv enteritis, dermatitis and amyloidosis
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What are methods to measure blood fibrinogen?
- TP plasma - TP serum
- Test used for thrombin time because clotting time directly depends on fibrinogen concentration. Reagent contains bovine thrombin and Ca++
Causes of fibrinogen concentration changes
Increase: acute inflammation (especially ruminants)
Decrease:
- liver function impairment
- advanced protein deficiency
- DIC
- sequestration after bleeding to body cavity
- chronic bleeding
- inherited a fibrinogenaemia (St. Bernard dog)
Measures to avoid in vitro glucose catabolism
- store sample cooled
- separate plasma from blood quickly
- coagulate RBC by i.e. 3% trichloric acetic acid
- take blood samples into tubes containing NaF (NaF inhibits enolase in RBCs by reaction between Mg and F)
Methods to measure blood glucose and theoretical background of these methods
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Glucometer.
It measures electric conductance in the fresh droplet of blood. Electric conductance is influenced by the ratio of cellular elements (mostly RBCs) - cells also conduct electricity but have a bigger resistance compared to plasma. Glucometers are callibrated for the physiological cell counts, thus if patient has anaemia the glucose level measured is lower and if patient has polycythaemia measured glucose is higher. In these cases enzymatic method can show reliable glucose concentration. - GOD/POD enzymatic method.
Causes of increased blood glucose concentration
TRANSIENT INCREASE
- lab errors
- stress (cats!)
- food intake
- xylazine effect
- cranial trauma or inflammation (rabies, Aujeszky disease)
- glucose containing fluid therapy
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CONSTANT INCREASE
- DM
- hyperadrenocorticism and GCC therapy
- progesterone effect
- enterotoxiemia (sheep)
Causes of decreased blood glucose
- lab error
- decreased energy status (ketosis of ruminants, growing pigs, puppies of small breeds!, starvation)
- insulin overdose
- anabolic steroid effect
- liver failure, terminal stage
- acute liver failure (fast depletion of liver glycogen after a very short hyperglycaemic phase)
- hypoadrenocorticism
- septicaemia
- hyperthyroidism
- paraneoplastic syndrome
Intravenous glucose tolerance test
IV glucose tolerance test is done when we suspect the onset of diabetes mellitus or insulinoma (if in two consecutive starving blood samples glucose concentration was above 11 mmol/l). Test should not be performed if blood glucose leve; is very high (>20 mmol/l)
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After 24 h starving glucose is applied IV (before that sample is taken too), then blood sampling at 5, 15, 30, 45, 60 min after the infusion, Blood glucose should be normalised at 30-60 min sampling point.
Oral glucose tolerance test (glucose absorption test)
We perform this test when we suspect chronic bowel disease, exocrine pancreatic insufficiency or it can be used instead of IV glucose tolerance test.
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After 24 h starvation glucose is given orally and blood conc is checked. Blood glucose should be increased twice as normal value at 30 min and should be normalised at q20 min after po administration.
What do we use as a marker of glucose average concentration in the 2-3 weeks period before sampling?
Fructosamine
