Page 1043 - Cote clinical veterinary advisor dogs and cats 4th

516 Hypokalemia

Differential Diagnosis Chronic Treatment PEARLS & CONSIDERATIONS
See p. 1239 for detailed differential diagnoses. • Vitamin D: calcitriol is the form recom- Comments
VetBooks.ir • Increased loss onset of action and short half-life. • Hypoalbuminemia is a common cause of
mended for maintenance therapy for its rapid
• Decreased absorption
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○ Loading dose is 10-15 ng/kg q 12h PO
• Laboratory error
incidental (total) hypocalcemia (ionized Ca
for 4 days.
• Sequestration
within reference range).
○ Maintenance dose is 5-10 ng/kg q 12h PO. • The most common causes of clinical
Initial Database Adjust dose to maintain normocalcemia. hypocalcemia are eclampsia, protein-losing
• CBC, serum biochemistry panel, urinalysis ○ Maximal effect is seen in 1-4 days. enteropathy, and surgical removal of para-
• Serum ionized calcium concentration ○ Recommend compounding as a liquid thyroid glands (e.g., bilateral thyroidectomy).
formulation to allow for small dosage • Do not measure calcium in EDTA-treated
Advanced or Confirmatory Testing adjustments. blood; EDTA chelates calcium, decreasing
Specific testing depends on history, exam, and • Calcium supplementation: calcium carbonate its concentration.
routine blood tests but may include (1 g contains 400 mg of elemental calcium) • Avoid the use of calcium chloride because
• Serum PTH concentration is recommended at a dosage of 12.5-25 mg/ it is caustic.
• Serum magnesium concentration kg elemental calcium q 12h PO. • Correction formulas used to compensate for
• Ethylene glycol test • After normocalcemia is achieved, the dose hypoalbuminemia are not accurate; measure
• Serum 25-hydroxyvitamin D and calcitriol of oral calcium can be slowly tapered and ionized calcium instead.
concentrations discontinued. Vitamin D must be continued
until the underlying disorder is corrected. Prevention
TREATMENT • Therapy with synthetic PTH is not currently • The modified intracapsular thyroidectomy
available. technique reduces the occurrence of post-
Treatment Overview operative hypocalcemia.
The goals of therapy are to increase serum Drug Interactions • Maintain pregnant bitch on high-quality
calcium concentration to a level that alleviates Calcium salts should not be added to fluids food throughout pregnancy.
clinical signs (but is not necessarily in the normal that contain lactate, acetate, bicarbonate, or
range), minimize the likelihood of hypercalcemia, phosphates because calcium may precipitate. Technician Tips
and reduce the magnitude of hypercalciuria. Facial pruritus is the earliest symptom of
Possible Complications hypocalcemia patients may display.
Acute General Treatment Subcutaneous administration of calcium should
Intravenous calcium infusion: be avoided because cases of severe, extensive Client Education
• Administer 10% calcium gluconate IV at a calcinosis cutis and epidermal necrosis resulting Patients receiving calcitriol should be monitored
dose of 0.5-1.5 mL/kg or 5-15 mg/kg slowly in euthanasia have been reported. for signs of hypercalcemia: polydipsia, polyuria,
to effect over 15-30 minutes. anorexia, vomiting, and lethargy.
• Electrographic monitoring is recommended Recommended Monitoring
during IV calcium administration. The • Monitor total serum calcium. Target level SUGGESTED READING
infusion should be slowed/discontinued if is 8-9.5 mg/dL (2-2.4 mmol/L) (i.e., just de Brito Galvão JF, et al: A quick reference on
bradycardia, ventricular premature complexes, below reference interval). hypocalcemia. Vet Clin North Am Small Anim
or shortening of the QT interval is observed. • Monitor for resolution of signs. Pract 47:249-256, 2017.
After clinical signs have improved, continue AUTHOR: Karen M. Tefft, DVM, MVSc, DACVIM
parenteral calcium administration. Calcium PROGNOSIS & OUTCOME EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
can be given as a continuous IV infusion at
60-90 mg/kg/day of elemental calcium (10% Depend on the underlying cause but are
calcium gluconate contains 9.3 mg/mL of generally good.
elemental calcium).

Hypokalemia

BASIC INFORMATION RISK FACTORS diuresis). However, signs attributable directly
Conditions that increase potassium loss (e.g., to hypokalemia include
Definition CKD, vomiting/diarrhea), or cause translocation • Muscle weakness or paralysis
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Serum potassium (K ) concentration < 3.5 mEq/L of potassium between the fluid compartments • Limb discomfort
• Limp neck posture
Epidemiology Clinical Presentation • Mental dullness
SPECIES, AGE, SEX DISEASE FORMS/SUBTYPES • Bowel hypomotility (species susceptibility
Any animal is susceptible. Hypokalemia related Usually a complication of other disorders, varies)
to chronic kidney disease (CKD) is most likely hypokalemia can be severe and result in acute • Polyuria/polydipsia
in older cats. Hypokalemic periodic paralysis or chronic clinical manifestations or can be an • Episodic muscular weakness (periodic familial
occurs in the first year of life. incidental finding. hypokalemia in cats)
GENETICS, BREED PREDISPOSITION HISTORY, CHIEF COMPLAINT PHYSICAL EXAM FINDINGS
Hypokalemic periodic polymyopathy (Burmese, History is often related to an underlying cause of Exam findings are often due to the underlying
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Bombay, Tonkinese cats, WNK3 mutation) K loss (e.g., vomiting/diarrhea, postobstructive cause of K loss (e.g., small, irregular kidneys).
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