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62 Section I: Diagnostics and Planning

comprehensive internal medicine or clinical biochemistry texts.
Considerations for some common serum biochemical clinical find-
ings are as follows [13,20].

Alterations in Glucose Levels
• Hypoglycemia: associated with hepatic disease, insulinoma,
hypoadrenocorticism, sepsis/toxemia, neonatal.
• Hyperglycemia: associated with diabetes mellitus, stress in cats.

Alterations in Blood Urea Nitrogen (BUN) and Creatinine
Levels
• Azotemia: prerenal, renal, or postrenal causes (evaluation of
urine specific gravity before fluid therapy is necessary to differen-
tiate prerenal from renal causes).
• Low BUN: due to hepatic insufficiency or low‐protein diet.
Increased Alkaline Phosphatase Activity
• Due to hepatic disease, steroid or anticonvulsant therapy, extra-
hepatic biliary obstruction, neoplasia, and normal increases
Figure 6.4 Dog with scleral hemorrhage due to immune‐mediated throm-
bocytopenia. Source: Courtesy of Dr. Shauna Blois. related to osteoblastic bone activity in growing animals.
Increased Alanine Aminotransferase Activity
• Associated with hepatic disease and severe muscle injury.
• Increased production: drugs (vincristine), myeloproliferative • Alanine aminotransferase levels may be normal in some animals
syndrome. with severe hepatic disease.
• Mixed or idiosyncratic: neoplasia, iron deficiency.
Decreased Albumin Concentration
Thrombocytopenia • Associated with hepatic disease, protein‐losing nephropathy or
• Increased destruction: immune‐mediated (Figure 6.4). enteropathy, severe exudative cutaneous lesions.
• Accelerated utilization: DIC, major vessel thrombosis, acute
severe hemorrhage. Alterations in Calcium Levels
• Increased storage site sequestration: splenic disease/neoplasia, • Hypercalcemia: paraneoplastic syndrome (lymphoma, anal sac
anaphylaxis, endotoxemia, drugs (barbiturates), hypoadrenocorticism. adenocarcinoma), primary hyperparathyroidism, hypervitami-
• Decreased production: pancytopenic syndrome, bone marrow nosis D, hypoadrenocorticism, chronic renal failure.
infiltration, chemotherapy. • Hypocalcemia: renal disease, pregnancy (eclampsia), hypovita-
• Mixed or idiosyncratic: infectious (rickettsial, FeLV, histoplasmo- minosis D, hypoparathyroidism.
sis), nonleukemic neoplasia, bacterial septicemia or endotox-
emia, severe inflammation or necrosis, uremia. Hypernatremia
Although automated platelet counts may be accurate, it is always • Associated with vomiting, diarrhea, renal failure, diabetes insipi-
indicated to review a peripheral blood smear, as platelet clumping dus, inappropriate fluid therapy, adipsia.
or changes in mean platelet volume can result in erroneous values,
especially in cats. In a blood smear, each platelet observed on a 100× Alterations in Potassium Levels
high‐power field represents approximately 20 × 10 /μL circulating • Hyperkalemia: acute or chronic renal failure, urinary tract
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platelets [15]. obstruction or uroabdomen, rhabdomyolysis, hypoadrenocorti-
In the absence of other concurrent hemostatic defects, excessive cism, diabetes mellitus with ketoacidosis, excessive supplementa-
surgical bleeding is uncommon if the platelet count is greater than tion and secondary to administration of some diuretics and
50 × 10 /μL and spontaneous bleeding is unlikely with counts above cardiac drugs. Pseudohyperkalemia has been reported in certain
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30 × 10 /μL [15,16]. However, no specific values have been shown to breeds such as the Shar‐pei, Akita and Shiba Inu [21,22].
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be predictive of surgical bleeding, despite data proving that human • Hypokalemia: vomiting, diarrhea, diuretic therapy, chronic renal
critical care patients with counts below 100 × 10 /μL present a failure, inappropriate fluid therapy.
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10‐fold increased risk of bleeding compared with those with counts Other frequently performed but more specific serum biochemi-
of 100–150 × 10 /μL [17–19]. cal tests include, but are not limited to:
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• blood gases;
• bile acids (preprandrial and postprandrial) and ammonia level
Serum Biochemistry (to evaluate hepatic function);
A comprehensive serum biochemistry panel is necessary to look for • endocrine assays such as thyroid, parathyroid hormone, adreno-
metabolic diseases that could be associated with the spinal neuro- corticotropic hormone, and cortisol levels;
surgical condition or could increase the anesthetic and surgical • anticonvulsant serum concentration;
risks. Review of all serum biochemical tests and possible alterations • serum osmolality and osmolal gap;
is beyond the scope of this chapter and the reader is referred to • serum protein electrophoresis;