Page 1045 - Cote clinical veterinary advisor dogs and cats 4th

Hypokalemia 517

However, findings attributable directly to Recommended Amount Potassium Chloride and Rate of Infusion
hypokalemia (if present) may include Serum Potassium
VetBooks.ir • Short, limited stride + Concentration mEq KCl to Add mEq KCl to Add Maximal Fluid Infusion Diseases and Disorders
• Weakness
Rate* (mL/kg/h)
(mEq/L)
to 250 mL Fluid
to 1 L Fluid
• Flaccid ventral cervical flexion
• Shallow respiratory movements/apnea (K
< 2.4 mEq/L) <2.0 20 80 6
+
• Cardiac arrhythmias (K < 2.4 mEq/L) 2.1-2.5 15 60 8
2.6-3.0 10 40 12
Etiology and Pathophysiology 3.1-3.5 7 28 18
See Hypokalemia on p. 516. 3.6-5.0 5 20 25
Pathophysiology:
• Two main causes: increased loss (most CAN DOSE ON BASIS OF mEq/L OVER 24 HOURS
common/severe) and translocation between +
fluid compartments Serum K Concentration (mEq/L) Dose of KCl in mEq/kg/24 Hours
• Hypokalemia increases cellular repolarization 3.0-3.5 2-3
and adversely affects cell depolarization.
• Hypokalemia affects cardiac excitation and 2.5-3.0 3-5
conduction, and renal function. <2.5 5-10
*So as not to exceed 0.5 mEq/kg/h. This rate can be exceeded in life-threatening hypokalemia by giving up to 1.5 mEq/kg/h with
DIAGNOSIS simultaneous electrocardiographic monitoring.
Modified from Greene RW, et al: Lower urinary tract disease. In Ettinger SJ, editor: Textbook of veterinary internal medicine, Philadelphia,
Diagnostic Overview 1975, Saunders, p 1572.
Potassium concentration should be measured
in any animal with weakness or a disorder
known to cause hypokalemia. Diagnostic Acute General Treatment chronic muscle functional impairment if fibrosis
efforts are typically geared toward the underly- • Potassium chloride typically favored for occurs.
ing disorder rather than the complication of parenteral use as additive to intravenous
hypokalemia. fluids PEARLS & CONSIDERATIONS
• When there is coexisting hypophosphatemia
Differential Diagnosis (e.g., during treatment for diabetic ketoaci- Comments
Any cause of weakness (p. 1295) dosis), potassium phosphate can be used to Recalcitrant hypokalemia sometimes improves
+
supply one-half of the K supplementation. when concurrent hypomagnesemia is addressed.
Initial Database
CBC, serum chemistry profile, urinalyses, ± Chronic Treatment Prevention
imaging studies performed to find cause of Oral potassium gluconate (commercial gel or • Supplement IV fluids with appropriate
+
+
hypokalemia (by definition, serum/plasma K powder): typical starting dose 1.0 mEq/kg/day quantity of K , especially in anorexic animals
< 3.5 mEq/L), with special attention to divided two or three times per day; adjust based or those with diuresis.
+
+
• Creatinine and blood urea nitrogen (kidney on recheck of [K ] • Monitor K regularly when there are condi-
failure) tions that predispose to hypokalemia.
• Urine specific gravity (isosthenuria in CKD, Drug Interactions
isosthenuria to hyposthenuria with diuresis) Angiotensin-converting enzyme (ACE) inhibi- Technician Tips
• Serum sodium (increased if hyperaldoster- tors, beta-adrenergic blockers may lead to excess • Flaccid ventral neck flexion in a cat should
+
+
onism) K retention during supplementation. prompt K measurement.
+
• Serum chloride (hypochloremic metabolic • K -containing fluids should not be used for
alkalosis) Possible Complications bolus administration as during cardiopulmo-
• Bicarbonate (increased with metabolic alka- Post-supplementation hyperkalemia, cardiac nary resuscitation.
losis, decreased with renal tubular acidosis) arrhythmia/arrest from overly rapid supple-
• CK and AST (increase with rhabdomyolysis) mentation SUGGESTED READING
DiBartola SP: Disorders of sodium and water:
Advanced or Confirmatory Testing Recommended Monitoring hypernatremia and hyponatremia. In DiBartola SP,
+
As based on clinical suspicion; may include Appropriate K supplementation is best gauged editor: Fluid, electrolyte and acid base disorders
+
blood gas analysis, diagnostic imaging, measure- by repeat serum K determinations. While on in small animal practice, ed 4, St. Louis, 2012,
ment of aldosterone and renin, or genetic testing IV fluids, daily monitoring is ideal. For oral Saunders.
(periodic polymyopathy in cats) home supplementation, repeat measures once AUTHOR: Michael Schaer, DVM, DACVIM, DACVECC
per week until stable; then recheck at routine EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
TREATMENT appointments (p. 169).
Treatment Overview PROGNOSIS & OUTCOME
+
Must address the underlying disorder; K
supplementation (orally or parenterally, depend- Depends on ability to resolve/address underly-
ing on presentation) is often indicated. ing cause. Hypokalemic myopathy may cause

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