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VETERINARY
HANDBOOK
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GASTROINTESTINAL |
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Trypsin-Like
Immunoreactivity (TLI) |
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Serum
TLI will detect exocrine pancreatic insufficiency (EPI)
in dogs and cats in a single blood sample. Samples must
be serum and the animals need to be fasted for at least
6 hours and preferably overnight.
Interpretation
Animals with EPI have very low levels of TLI. Animals
with pancreatitis have very high levels of TLI.
Acute pancreatitis gives rise to very high levels due
to increased amounts of trypsinogen released into the
general circulation. It is very important to sample suspected
cases of pancreatitis as early as possible to obtain an
accurate diagnosis, as the levels of TLI decrease as the
condition progresses. |
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Vitamin B12/Folate |
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Serum vitamin B12 and folate
concentrations are useful in diagnosing small intestinal
malabsorption or bacterial overgrowth in dogs and cats.
A single serum sample is required.
Interpretation
Low serum folate suggests malabsorption in the proximal
small intestine.
Low vitamin B12 suggests malabsorption in the distal small
intestine.
Low or normal vitamin B12 together with high folate suggests
bacterial overgrowth. |
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Insulin |
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Insulin levels in normal fasting
dogs are less than 20 mU/mL. Samples for insulin assay should
be taken during a period of hypoglycaemia, if the insulin levels
are greater than 20 mU/mL this is considered to be excessive
secretion.
Guidelines for the interpretation of
fasting insulin
| Insulin greater than 20 mU/mL |
High insulin, insulinoma very
likely |
| Insulin 10 - 20 mU/mL |
High/normal insulin, insulinoma likely |
| Insulin 5 - 10 mU/mL |
Low/normal insulin, insulinoma possible
if glucose very low |
| Insulin less than 5.0 mU/mL |
Undetectable/low insulin - insulinoma very
unlikely |
Repeat estimation of borderline results may be required to confirm
the diagnosis of insulinoma. |
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Insulin:Glucose
Ratio (IGR) |
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The IGR is useful when absolute
hyperinsulinaemia (insulin >20 mU/mL) is not present and the
insulin levels are not diagnostic alone. Glucose and insulin
are measured on the same sample.
Calculate as follows:-
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Serum Insulin
(mU/mL)
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= IGR (U/mol) |
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Serum Glucose (mmol/L)
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Interpretation
IGR of >4.2 U/mol is consistent with insulinoma. |
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Amended Insulin/Glucose
Ratio (AIGR) |
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The AIGR is reported to be more
helpful in some cases and is calculated on the assumption that
insulin levels should be undetectable if the blood glucose falls
below 30 mg/dL.
NOTE: If glucose is <30mg/dL then
the divisor becomes 1.0.
Calculate as follows:-
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Serum Insulin
(mU/mL) x 100
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= AIGR (U/mol) |
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(Serum Glucose mmol/L
x 18.02) - 30
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Interpretation
AIGR of >30 is consistent with insulinoma. |
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Equine Insulin |
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Equine Insulin Horses with PIA
often have very high serum insulin levels due to peripheral
insulin resistance. |
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Fructosamine |
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Fructosamine is useful to assess
long term glycaemic control in dogs and cats. It is a measure
of plasma proteins which have undergone non-enzymatic glycation
and is therefore related to the mean blood glucose concentration
over the previous 1 - 3 weeks.
Fructosamine levels greater than 400 mmol/L are consistent with
poor diabetic control. |
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