Clinical biochemistry (year 2) Flashcards
1
Q
what is the role of diagnostic tests?
A
to conform/refute a clinical hypothesis so shouldn’t be carried out blind
2
Q
what must be done before taking blood?
A
history
physical exam
identify clinical problems
differential diagnosis
3
Q
what are the two types of tests?
A
screening
confirmation
4
Q
what samples can be taken?
A
urine, blood, faeces, cavitary fluid, synovial fluid, CSF
5
Q
define clinical biochemistry
A
analysis of samples of bodily fluid
6
Q
what is plasma?
A
extracellular fluids plus additional proteins
7
Q
what are the functions of plasma?
A
transport - nutrients, hormones, metabolites
clotting
osmolarity maintenance
oncotic pressure maintenance
8
Q
what is the difference between whole blood and plasma?
A
plasma doesn’t have any cells
9
Q
what is the main difference between the collection of plasma and serum?
A
serum is allowed to clot so doesn’t contain clotting factors
plasma still contains coagulation factors by using an anticoagulant
10
Q
what is chemicals is blood placed in to prevent clotting to obtain plasma?
A
lithium heparin
sodium citrate
11
Q
when measuring glucose in plasma/serum what tube is blood collected into?
A
NaFluoride/oxalate or NaFluoride/EDTA tube
12
Q
what colour are NaFluoride/oxalate or NaFluoride/EDTA tubes?
A
grey top
13
Q
what does fluoride inhibit?
A
glycolysis - so glucose isn’t used up and can be measured
14
Q
why may a decrease in concentration of analytes in serum occur?
A
decreased input
increased output
15
Q
why might input be decreased causing a decrease in concentration of serum analytes?
A
decrease synthesis, nutritional deficiency, poor absorption, lack of precursors
16
Q
why might input be increased causing a decrease in concentration of serum analytes?
A
excessive demand, increased excretion, pathological loss
17
Q
why may an increase in concentration of analytes in serum occur?
A
increased input
decreased output
18
Q
some changes to plasma analytes can be relative, what does this mean?
A
changes caused by increased/decreased water - haemoconcentration
19
Q
what is the reference interval?
A
range of values encompassing 95% of a tested population of apparently healthy animals
20
Q
why is 95% used as a reference interval instead of 100%?
A
maximise detection of diseased animals
21
Q
what is the term used for decreased albumin in serum?
A
hypoalbuminaemia
22
Q
what are pre-analytical errors?
A
errors that happen before test is carried out
23
Q
what are some common pre-analytical errors?
A
labelling, anticoagulation, contamination, improper handling, inappropriate storage
24
Q
what may an abnormal increase in potassium during blood sampling be due to?
A
EDTA contamination
25
what is accuracy?
how close the result is to the true value
26
what is precision?
reproducibility of the laboratory methods
27
what is sensitivity?
likelihood of a positive result when disease is present
28
what is specificity?
likelihood of a negative result when disease is absent
29
what is a positive predictive value?
likelihood that a patient with a positive result has the disease
30
what is a negative predictive value?
likelihood that a patient with a negative result does not have the disease
31
what are the proteins measured in total protein?
albumin
| globulins (include clotting factors)
32
how can total protein be measured?
refractometry
| biuret method
33
where is albumin produced?
hepatocytes
34
where is albumin catabolised?
most tissues
35
what is the function of albumin?
carrier protein
| role in oncotic pressure
36
what is albumin a carrier protein for?
```
unconjugated bilirubin
bile acid
free-fatty acid
drugs
hormones
calcium
```
37
where are globulins produced?
B lymphocytes
plasma cells
liver
38
what does serum protein electrophoresis separate proteins based on?
size of molecule
| electrical charge
39
what is increased levels of albumin called?
hyperalbuminaemia
40
hyperalbuminaemia is usually only relative, what does this mean?
body doesn't overproduce albumin
41
what may be a causes of hyperalbuminaemia?
dehydration
42
what may hyperalbuminaemia be accompanied by?
increased PCV
azotaemia
increase of all proteins
43
what is increased levels of globulins called?
hyperglobulinaemia
44
what could cause hyperglobulinaemia?
dehydration
| inflammation
45
how is hyperglobulinaemia characterised by electrophoresis?
monoclonal or polyclonal
46
what is monoclonal hyperglobulinaemia?
production of a single type of immunoglobulin usually due to neoplasia
47
what is the most common neoplasia that causes monoclonal hyperglobulinaemia?
multiple myeloma
48
what are the types of protein associated with inflammation? (3)
positive acute-phase
negative acute phase
delayer response
49
what are some examples of positive acute phase proteins?
haptoglobin
| fibrinogen
50
what are some examples of negative acute phase proteins?
albumin
| transferrin
51
what are some examples of delayed response proteins?
complement
| immunoglobulin
52
what do positive acute phase proteins do during inflammation?
increase in number
53
what do negative acute phase proteins do during inflammation?
decrease in number
54
are acute phase proteins specific?
no (non-specific)
55
what are acute phase proteins under the influence of?
cytokines
56
what do rapid reacting acute phase proteins do?
increase within 24 hours then decrease rapidly after the insult is removed
57
what are some examples of rapid reacting acute phase proteins?
serum amyloid A
| C reactive protein
58
what are some examples of late reacting acute phase proteins?
haptoglobin
| fibrinogen
59
what are the causes of hyperfibrinogenaemia?
inflammation
| dehydration
60
how can hyperfibrinogenaemia be measured?
heat precipitation
| coagulation assay
61
what may cause hypofibrinogenaemia?
```
decreased synthesis from liver
increased consumption (fibrinogeneolysis)
```
62
what tests can be effected by decreased fibrinogen production?
fibrinogen concentration
PT
PTT
TP
63
what is the term used if all proteins are low?
panhypoproteinaemia
64
what could cause panhypoproteinaemia?
acute haemorrhage
| GI loss
65
what are some causes of hypoaluminaemia due to decreased production?
chronic liver disease
prolonged malnutrition
maldigestion/malabsorption
66
what are some causes of hypoaluminaemia due to increased loss?
kidney-glomerular leakage
GI loss
burns
67
when is hypoglobulinaemia seen?
failure of passive transfer in neonates
| combine immunodeficiency in foals
68
what are cholesterol and triglyceride required to be incorporated with to be transported in blood?
into a soluble lipid-protein complex (lipoprotein)
69
what are the types of lipoproteins?
chylomicrons
very low density lipoprotein
low density lipoprotein
high density lipoprotein
70
what do chylomicrons deliver to cells?
dietary triglycerides
71
what do very low density lipoproteins deliver to cells?
triglycerides made by the liver
72
what do low density lipoproteins deliver to cells?
cholesterol
73
what do high density lipoproteins do?
pick up tissue cholesterol for elimination in bile
74
what lipids are tested for in blood?
total cholesterol and triglycerides
75
what is lipaemia primarily caused by?
increased chylomicrons
| increased VLDLs
76
what does plasma look like during lipaemia?
opaque plasma
77
what artefacts can be caused by lipaemia?
```
enhanced tendency to haemolysis
falsely high haemoglobin
falsely high TP
unreliable fructosamine
low sodium
```
78
what is requires when measuring triglycerides?
the animal has fasted
79
what may cause hypercholesterolaemia?
```
endocrine disease
hepatic disease
steroid administration
diet
nephrotic syndrome
```
80
why may enzyme activity be increased? (5)
```
cell damage
impaired enzyme clearance
physiological
induction
artifactual
```
81
what are typical diagnostic uses of enzyme activity in serum? (3)
hepatocyte damage
exocrine pancreas damage
myocyte damage
82
why may enzymes leak from myocytes? (3)
degradation
necrosis
inflammation
83
what are enzymes of muscles that can be measured?
```
creatine kinase (CK)
aspartate aminotransferase (AST)
lactate dehydrogenase (LDH)
```
84
what is the most tissue specific enzyme of muscle that can be measured?
creatine kinase (CK)
85
what is the function of creatine kinase?
make ATP available for muscle contraction
86
what is creatinine?
waste product from the spontaneous breakdown of creatine
87
what is creatinine used to assess?
kidney function
88
where in the cell in creatine kinase found?
cytoplasm
89
where else (other than skeletal muscle) is creatine kinase found?
brain (CSF)
90
is creatine kinase sensitive and specific?
yes (rapid increase/decrease)
91
what is the degree of increase of creatine kinase proportional to?
degree of muscle damage
92
what could a small increase in creatine kinase be due to?
IM injections
| traumatic venupuncture
93
what does persistent increase of creatine kinase mean?
ongoing muscle damage
94
what are some causes of muscle injury?
```
degenerative (hypoxia)
metabolic
neoplasia
nutritional
inflammatory
toxic
trauma
```
95
what can interfere with creatine kinase levels, causing an artifictual increase?
haemolyiss (releases other enzymes)
| hyperbilirubinaemia
96
what enzymes are used to identify injury to pancreatic cells? (2)
amylase
| lipase
97
what is the most common reason for increase in amylase and lipase?
inflammation (pancreatitis)
98
what enzymes can be used to assess liver function?
```
alanine aminotransferase (ALT)
aspartate aminotransferase (AST)
lactic dehydrogenase (LDH)
sorbitol dehydrogenase (SDH)
glutamate dehydrogenase (GLDH)
```
99
where is ALT found?
mainly liver
| some in muscle
100
what animals is ALT mainly used in?
small
101
where is AST and LDH found?
liver
| muscle
102
where is SDH and GLDH found?
liver specific
103
what animals is GLDH mainly used in?
large
104
what are the liver leakage enzyme that are measured not correlative of? (3)
reversibility of injury
hepatic function
prognosis
105
what is cholestasis?
stopping of the flow of bile
106
what enzymes can be used to assess cholestasis? (cholestatic liver enzyme)
ALP (alkaline phosphatase)
| GGT (gammaglutamil transferase)
107
what is the major measurable isoform of ALP?
liver-ALP
108
during cholestasis what happens to the concentration of ALP?
increases
109
where is liver-ALP found?
bound to plasma membrane of hepatocytes and biliary epithelium
110
what does an increase in GGT indicate?
cholestasis
111
what species is GGT a more sensitive measure of cholestasis?
cats
horses
cattle
112
what may lead to decreased bile flow/excretion?
intrahepatic - hepatocellular swelling
extrahepatic - bile duct obstruction
functional
113
what are the markers of cholestasis?
bilerubin
bile acids
cholesterol
cholestatic enzymes
114
in horses why may be see hyperbilirubinaemia?
due to fasting/starving
115
what are the clinical signs of hyperbilirubinaemia?
jaundice
| bilirubinaemia
116
what could cause hyperbilirubinaemia? (4)
cholestasis
haemolytic anaemia
reduced hepatocellular function
fast/starving in horses
117
what functions of the liver can be testing in clinical biochemistry?
uptake/excretion of bilirubin/bile acids
ammonia to urea conversion
synthesis of metabolites
immunological function
118
what functions would be decreased if there was alterations of hepatic blood flow?
uptake/excretion of bile acids
ammonia to urea conversion
immunological function
119
what are the major sources of glucose? (2)
dietary absorption
| liver production
120
what are the processes that produce glucose in the liver?
glycogenolysis
| gluconeogenesis
121
what promotes the process of glycogenolysis?
catecholamines
| glucagon
122
what promotes the process of gluconeogenesis?
corticosteroids
glycogen
growth hormone
123
what regulates glucose metabolism?
absorption
insulin production
insulin antagonists
124
what is the best tube for collecting a glucose sample into if it is being sent off for analysis?
fluoride oxalate
125
what is a common cause of transient hyperglycaemia?
adrenalin (fear/excitement)
126
what are the causes of hypoglycaemia? (5)
```
excessive use
reduced hepatic storage
insufficient diet
excessive insulin/analogues
lack of corticosteroid
```
127
what could cause excessive use of glucose?
sepsis
neoplasia
excessive physical exertion
128
what are common causes of hyperglycaemia? (5)
```
after a meal
cathecolamines
iatrogenic (exogenous glucose administration)
insulin antagonism
diabetes mellitus
```
129
is glucose normally present in urine?
no (reabsorbed in proximal tubules)
130
what is glucose in urine called?
glucosuria
131
what does glucosuria usually mean in dogs?
diabetes mellitus
132
other than glucose concentration, what else can be measure to confirm diabetes?
glycated proteins
133
how are glycated proteins formed?
glucose slowly reacts with amino acid groups on all proteins
134
what is the rate of reaction of glycated protein formation dependant on?
blood glucose concentration
135
what is the glycated protein measured in animals?
fructosamine
136
what is fructosamine?
irreversibly glycated albumin
137
what will be the difference in fructosamine of a diabetic and stressed cat?
diabetic - high
| stress - low
138
what electrolytes are mainly present extracellularly?
sodium
chloride
bicarbonate
139
what mechanisms control sodium concentration? (3)
thirst
RAAS
ADH
140
what ways can alter sodium concentration?
loss of sodium/water
| loss of just water
141
what are the overall causes of hyponatraemia? (2)
loss of sodium
| water retention
142
what are some causes of loss of sodium rich fluids?
vomiting/diarrhoea
kidney
skin (burns/sweat)
143
what is the most common cause of hypernatraemia?
water loss in excess of sodium
144
what could cause water loss in excess of sodium?
fever/panting
lack of ADH
inadequate water intake
osmotic diuresis
145
what is high blood sodium called?
hypernatraemia
146
what does chloride follow?
sodium (increase/decrease together)
147
what is a causes of chloride increasing/decreasing without sodium?
vomiting pure stomach continents (HCl)
148
what effect does aldosterone have on potassium?
increases excretion
149
what could cause hyperkalaemia?
increased intake
reduced renal excretion
movement out of cell
150
what could cause hypokalaemia?
reduced intake
renal losses
GI losses
movement into cells
151
what can cause potassium to move out of a cell?
acidosis
| lack of insulin
152
what can cause potassium to move into a cell?
alkalosis
| insulin
153
what regulates calcium and phosphorus? (3)
parathyroid hormone
vitamin D3
calcitonin
154
what effect does increased parathyroid hormone have on calcium and phosphorus?
hypercalcaemia
| hypophosphataemia
155
what else other than the parathyroid can release parathyroid hormone related protein?
tumours of some organs
156
what is parathyroid hormone opposed by?
calcitonin
157
where is calcitonin secreted?
thyroid C-cells
158
what are the byproducts of nitrogen metabolism used as markers of renal function? (2)
urea
| creatinine
159
what is a nephron?
functional unit of the kidney formed from glomerulus, bowman capsule and collecting duct
160
where is urea made?
liver
161
what group of animals is urea not used as a measure of GFR?
ruminants
162
why is urea not used to measure GFR in ruminants?
because the excrete some in saliva and its degrades in rumen
163
where is creatinine produced?
muscle
164
how is creatinine produced?
degradation of muscle (proportional to muscle mass)
165
is creatinine or urea reabsorbed in the kidney?
creatinine - no reabsorption
| urea - reabsorption
166
what is uraemia?
clinical syndrome resulting from loss of kidney function
167
are all uraemic patients azotaemic?
yes
168
are all azotaemic patients uraemic?
no
169
what is azotaemia?
increased creatinine/urea
170
what could be the cause of increased urea?
decreased GFR
GI haemorrhage
high protein diet
recent meal
171
what could be the cause of decreased urea?
reduced production
| low protein diet
172
what could be the cause of increased creatinine?
decreased GFR
| high muscle mass
173
what could be the cause of decreased creatinine?
low muscle mass
174
what is prerenal azotaemia due to?
dehydration
decreased CO
increased production
175
what is postrenal azotaemia due to?
urine leakage/blockage
176
how can prerenal azotaemia be differentiated from other azotaemia?
high urine concentration
dehydration/hypovolaemia signs
responds to fluid therapy
177
how can azotaemia be differentiated from other azotaemia?
low urine concentration
| no response to fluid therapy
178
how can postrenal azotaemia be differentiated from other azotaemia?
clinical evidence (eg. hyperkalaemia)
179
what are the renal influences on urine specific gravity? (3)
number of functional nephrons
tubular function
hydration status
180
what are the extra renal influences of urine specific gravity?
```
ADH release/action
medullary concentration gradient
osmotic forces
drug therapy
behaviour
```
181
why must urine be analysed rapidly after sampling? (5)
```
cells disintegrate
pH rises (carbon dioxide evaporates)
crystals form
bilirubin/urobilinogen breakdown
bacteria grow/die
```
182
what could a red coloured urine be due to? (3)
haematuria
haemoglobinuria
myoglobinuria
183
what could a dark yellow/brown coloured urine be due to?
bilirubinuria
184
how is haematuria and pigmenturia differentiated? (2)
haematuria contains erythrocytes in the sediment
| colour doesn't clear with centrifugation in pigmenturia
185
how can myoglobinuria and haemoglobinuria be differentiated?
myoglobin - urine red but plasma clear
| haemoglobinuria - urine red and plasma red
186
what could cloudy urine be due to?
```
mucus
bacteria
lipids
sperm
salts
increased cellular eliments
crystalluria
```
187
what is used to measure urine specific gravity?
refractometer
188
what is specific gravity?
measure total solute concentration of urine (weight compared to distilled water)
189
what is urine specific gravity used for?
confirm polyuria
evaluate kidney concentrating ability
differentiating renal and pre-renal azotaemia
190
what is the most common cause of protein in urine?
pyuria
191
what could be the cause of ketones in urine?
diabetes
| negative energy balance
192
what is the most common urinary crystals seen?
struvite (alkaline urine)
