Page 2639 - Cote clinical veterinary advisor dogs and cats 4th

1348 Glucose, Blood Glucosuria

Next Diagnostic Steps to Consider serum total protein concentration. If there Relative Cost: $$ (must order total protein
if Levels Are Low is concern for inaccuracy in either of these and albumin, or a panel)
VetBooks.ir and biochemistry values, particularly albumin, questioned. Sample hemolysis and/or lipemia Pearls
reported values, the globulin value should be
Consider with signalment, presenting complaint,
may impact results, but sources of interference
to prioritize differentials. If hypoalbuminemia
Electrophoretic evaluation is necessary to deter-
is present, interpret along with physical exam
findings and CBC results to determine likely vary with analyzer and method. mine increases in specific globulin fractions.
cause of panhypoproteinemia. Specimen Collection and Handling AUTHOR: Mary Leissinger, DVM, MS, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
Serum (red-top tube). If heparinized plasma
Lab Artifacts is substituted, total protein and calculated
Globulins are calculated by subtracting the globulins will be higher due to the presence
measured albumin concentration from measured of fibrinogen.

Glucose, Blood

Definition Causes of Abnormally Low Levels • Decrease: excess insulin (exogenous or
Blood concentration of the sugar utilized for Paraneoplastic (insulinoma, leiomyosarcoma, insulinoma), ethanol toxicity, treatment with
energy production others), insulin overdose, neonatal or juvenile salicylates, sulfonylurea, xylitol, o,p’-DDD
hypoglycemia, advanced liver disease, congenital
Physiology portosystemic shunt, extreme exertion, sepsis, Lab Artifacts
Carbohydrates in the diet are catabolized to hypoadrenocorticism, hypopituitarism, long- • Decrease: delayed separation of serum or
glucose for absorption and transport to tissues. term starvation (rare cause of hypoglycemia plasma from red blood cells results in artificial
The liver produces glucose via gluconeogenesis in adults) or malabsorption, glycogen storage depression due to utilization of glucose by
and glycogenolysis, and stores glucose as gly- diseases, intoxication (e.g., xylitol, oleander), blood cells.
cogen or converts glucose to amino acids and artifact (delay in separating red blood cells • Increase: lipemia
lipids. Blood glucose is primarily regulated by from serum/plasma, erythrocytosis or extreme • Point-of-care glucometers often underesti-
dietary intake and the hormones insulin and leukocytosis). See p. 1240. mate blood glucose (especially those designed
glucagon, which regulate its hepatic storage, for use in humans).
release, and tissue utilization. Next Diagnostic Steps to Consider
if Levels Are Low Specimen Collection and Handling
Reference Interval Resample to verify persistent hypoglycemia. Serum (red top tube) or heparinized plasma
• Dogs: 60-125 mg/dL (3.3-6.9 mmol/L); cats: Correlate with other clinical and laboratory (green top tube). Separate from cells within 30
70-150 mg/dL (3.9-8.3 mmol/L) findings. Evaluate for insulinoma (p. 552). minutes after sample collection. Use fluoride
• To convert from mg/dL to mmol/L, multiply oxalate anticoagulant (gray top tube) if plasma
by 0.0555. Important Interspecies Differences separation is not possible: stable at 2°C-8°C
Hyperglycemia due to excitement-induced for 4 days.
Causes of Abnormally High Levels epinephrine release is common in cats.
Diabetes mellitus, glucose-containing fluids, Relative Cost: Single test $; included in
hyperadrenocorticism, hyperthyroidism, Drug Effects many chemistry panels $-$$$
acromegaly/hyperpituitarism, acute pancreatitis, • Increase: glucocorticoids, adrenocorticotropic
excitement-induced epinephrine release (primar- hormone, intravenous fluids containing dex- AUTHOR: Ruanna E. Gossett, DVM, PhD, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
ily cats), postprandial (minor elevation). See trose, growth hormone, glucagon, megestrol
p. 1235. acetate, thiazide diuretics, xylazine, ketamine
(cats), morphine, and phenothiazine tranquil-
Next Diagnostic Steps to Consider izers
if Levels Are High
Assess for persistent hyperglycemia, glucosuria,
ketonuria, +/- serum fructosamine.

Glucosuria

Definition Physiology concentration of glucose in the ultrafiltrate
The presence of glucose in urine secondary Glucose is freely filtered by the glomerulus and exceeds the maximum reabsorptive capacity
to overwhelmed or defective renal tubular is subsequently reabsorbed by the proximal renal of the renal tubules. The point at which the
reabsorption tubular epithelial cells. Glucose reabsorption reabsorptive capacity of the renal tubules is
is dependent upon the glomerular filtration exceeded is termed the renal threshold and
Synonym rate, tubular reabsorption rate, and urine flow. differs among species.
Glycosuria During hyperglycemic states, the increased

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