Page 2580 - Cote clinical veterinary advisor dogs and cats 4th

1304 Alkaline Phosphatase (ALP)

Causes of Abnormally High Levels stim) to evaluate the hypothalamic-pituitary- Pearls
Adrenal neoplasia, low sodium intake, non- adrenal axis. • This test is rarely indicated as other simpler
VetBooks.ir hyponatremia Drug Effects hyperaldosteronism (e.g., ultrasonographic
methods are available for discovery of
adrenal diseases that result in hypovolemia or
imaging of adrenal mass).
• Decrease: ACE inhibitors and nonsteroidal
Next Diagnostic Steps to Consider
antiinflammatory drugs
if Levels Are High • Increase: spironolactone • Plasma aldosterone to renin ratios may aid
in interpretation of inappropriate versus
Abdominal ultrasound to rule out adrenal appropriate circulating values. However, may
neoplasia. Specimen Collection and Handling have limited clinical value due to availability
Plasma collected from EDTA tube (lavender of renin assay and collection requirements.
Causes of Abnormally Low Levels top tube) or heparin (green top tube). Plasma
Hypoadrenocorticism (Addison’s disease), adrenal should be separated from the erythrocyte mass AUTHOR: Erin N. Burton, DVM, MS
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
atrophy (idiopathic, secondary to medication, as soon as possible and frozen until shipment.
pituitary disease), high sodium intake Ship on ice.
Next Diagnostic Steps to Consider Relative Cost: $$
if Levels Are Low
Rule out medication administration. Adreno-
corticotropic hormone stimulation test (ACTH

Alkaline Phosphatase (ALP)

Definition activity (bone growth, fracture repair, Relative Cost: $ (total serum); $$ (C-ALP
Membrane-associated enzyme found in liver, osteosarcoma) specific)
bone, colostrum, and many other tissues.
Physiologic role is not established. Next Diagnostic Steps to Consider Pearls
if Levels Are High • Most dogs with increased ALP activity do
Synonyms Review medication history; evaluate hepato- not have hyperadrenocorticism. Increased
AKP, sALP, SAP, ALKP biliary structure and function; pursue possible ALP warrants a detailed review of history
causes based on relevant history, exam, and and physical examination before determining
Physiology other clinicopathologic findings. Young, healthy whether testing for hyperadrenocorticism is
Total ALP activity in most domestic mammals dogs may have slightly to moderately elevated justified.
results from two isoforms of a single isoenzyme ALP attributed to bone growth. • C-ALP is used as a screening test but is not
produced by the tissue-nonspecific ALP gene: specific for hyperadrenocorticism, as stress or
liver (and biliary) associated (L-ALP) and Important Interspecies Differences an iatrogenically administered corticosteroid
bone associated (B-ALP). The tissue-specific • Dogs: corticosteroid induction unique to may increase C-ALP.
(intestinal associated) isoenzyme produced by dogs • Increased ALP activity, especially without
the I-ALP gene does not result in increases • Cats: up to 75% of hyperthyroid cats have increased bilirubin, warrants investigation
in total serum ALP activity. A third isoform, increased ALP activity caused by L- and for hyperthyroidism in older cats.
corticosteroid-induced ALP (C-ALP), is B-ALP. Short serum half-life (6 hours in • Benign familial increase in ALP (B-ALP)
unique to the dog. Its activity is stimulated cats vs. 3 days in dogs), so slightly increased has been reported in related Siberian Husky
by endogenous and exogenous corticosteroids. serum ALP activity in cats may be more puppies.
Most ALP assays include total enzyme activity, clinically significant than a slight increase • Scottish terriers are more likely to have
but specific tests for liver and corticosteroid in dogs. increased ALP with and without associated
isoenzymes of ALP are available. disease compared to other dog breeds.
Drug Effects
Reference Interval Increase: corticosteroids, phenobarbital, AUTHOR: Carrie L. Flint, DVM, DACVP
Dogs: 0 to 150 U/L; cats: 4 to 80 U/L primidone, prednisone, thyroxine EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
Causes of Abnormally High Levels Specimen Collection and Handling
Cholestasis, endocrinopathy (e.g., hyperadre- Serum (red top tube); allow to clot, centrifuge,
nocorticism, hyperthyroidism in cats), drug collect serum, refrigerate, ship chilled. Can also
(glucocorticoids, phenobarbital), osteoblast be assessed from plasma (green top tube).

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