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Hyperkalemia 495

• Co-oximetry (carbon monoxide intoxication) Possible Complications arrhythmias, or other systemic signs should
• CT or MRI (embolism evaluation) Reperfusion injury, tissue necrosis arouse the suspicion of mast cell tumor or
VetBooks.ir TREATMENT PROGNOSIS & OUTCOME Techician Tip Diseases and Disorders
pheochromocytoma.

Treatment Overview
perceived color change (e.g., reddening) is real.
Goal of treatment is resolution of the underlying Varies, depending on the underlying cause Good lighting is important in assessing if a
cause, with special attention paid to ensuring PEARLS & CONSIDERATIONS
adequate tissue perfusion. SUGGESTED READING
Comments Lima I, et al: The peripheral perfusion index in
Acute General Treatment • Presenting signs (true chief complaint vs. reactive hyperemia in critically ill patients. Crit
• Supportive as needed: analgesia, oxygen routine visit for preventive/annual exam) Care 8(suppl 1):53, 2004.
supplementation (p. 1146), restoration of are extremely valuable in determining the AUTHOR: Adam J. Reiss, DVM, DACVECC
perfusion, cooling and/or elevation of the importance of a patient’s hyperemia. EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
affected region • Intermittent/episodic hyperemia associ-
• Treat underlying disorder ated with behavioral changes, cardiac

Hyperkalemia

BASIC INFORMATION HISTORY, CHIEF COMPLAINT chylothorax, ascites, term pregnancy; these
• Acute: often dramatic and life-threatening; may be associated with hyponatremia (pseudo
Definition produces diffuse muscle weakness, mental Addison’s disease)
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A serum potassium (K ) concentration depression, anorexia. • Pseudohyperkalemia (e.g., thrombocy-
> 5.5 mEq/L; concentrations > 7.5 mEq/L are • Chronic: slower in onset and not as dramatic. tosis, extreme leukocytosis [>100,0000],
potentially harmful. Decreased appetite, weight loss, intermittent hemolysis [especially Japanese breed
vomiting and diarrhea, and skeletal muscle dogs])
Synonym weakness can occur. • Spurious
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Elevated serum potassium (K ) concentration • History often reflects cause of hyperkalemia Mechanism of damage due to hyperkalemia:
(e.g., stranguria with lower urinary obstruc- • Affects primarily skeletal and cardiac muscle
Epidemiology tion; vomiting with acute kidney injury tissues
SPECIES, AGE, SEX (AKI) or hypoadrenocorticism). • Life-threatening effects on heart
Any patient can be affected. ○ Initially increased and subsequently
PHYSICAL EXAM FINDINGS depressed excitability and conduction
GENETICS, BREED PREDISPOSITION • With severe hyperkalemia, may find: velocity secondary to persistent depolar-
• Hyperkalemia: hypoadrenocorticism (stan- ○ Generalized muscle weakness ization and inactivation of the sodium
dard poodles) ○ Weak pulse channels in the cell membranes, causing
• Pseudohyperkalemia: hemolysis or throm- ○ Prolonged capillary refill time cardiac conduction abnormalities
bocytosis in Japanese breeds (Akita, shiba); ○ Bradycardia, especially in setting of • Skeletal muscle weakness occurs.
English springer spaniel with phosphofruc- dehydration when heart rate should be
tokinase deficiency increased DIAGNOSIS
○ Irregular heart rate
RISK FACTORS ○ Body temperature normal or hypothermia Diagnostic Overview
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• Urinary obstruction • Other findings related to underlying cause (e.g., Confirm accurate K measurement. Cause is
• Urinary bladder rupture distended bladder from urethral obstruction) often readily identified by history, exam, and
• Hypoadrenocorticism (i.e., Addison’s disease) minimal laboratory testing and imaging studies.
• Oliguria and anuria Etiology and Pathophysiology Unless mild, perform ECG.
• Type 4 renal tubular acidosis Cause of hyperkalemia: see Hyperkalemia
• Mineral acid metabolic acidosis (not organic (p. 1235) Differential Diagnosis
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acidosis such as lactic acidosis) • Decreased K excretion, as in hypoaldoste- • Pseudohyperkalemia
• Iatrogenic factors (drugs, oversupplementa- ronism, AKI, urinary bladder rupture or • Any cause of bradycardia (p. 1204)
tion) outflow obstruction, or type 4 renal distal • Primary myocardial disease
tubular acidosis and with certain drugs • Many of the causes of skeletal muscle weak-
ASSOCIATED DISORDERS (e.g., angiotensin-converting enzyme [ACE] ness (p. 1295)
• Bradycardia inhibitors, potassium-sparing diuretics, beta-
• Atrial standstill blockers) Initial Database
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• Abnormal electrocardiogram (ECG) com- • K translocation from intracellular to extracel- • Thorough history and physical exam
plexes lular fluid space (e.g., mineral acid–caused • CBC: eosinophilia, lymphocytosis, and
• Skeletal muscle weakness metabolic acidosis, hypertonicity, tumor lysis anemia may occur with hypoadrenocorticism
syndrome, hyperkalemic periodic paralysis, • Serum biochemistry profile
Clinical Presentation massive tissue destruction [rare]) ○ Serum electrolytes: elevated K with
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DISEASE FORMS/SUBTYPES • Miscellaneous conditions (cause poorly simultaneous decreased sodium concentra-
Acute and chronic; subclinical or clinical understood), such as whipworm enterocolitis, tions can occur with hypoadrenocorticism,
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