Page 112 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

102 ELECTROLYTE DISORDERS

• Administration of K-deficient fluids?
• Drug administration
(e.g., loop diuretics, thiazides)
Yes No

Consider • Administration of insulin and glucose?
iatrogenic hypokalemia • Alkalemia?
• Catecholamines?
• Albuterol overdosage?
• Burmese cat?
Yes No
+
Translocation of K ECF Æ ICF Vomiting or diarrhea?
FE £ 6% Yes No FE > 6%
K
K
Gastrointestinal loss of K + Recent relief of
urethral obstruction?
Yes No

Post-obstructive diuresis Azotemia, isosthenuria,
PU/PD?
Yes No
• Chronic renal failure (cats > dogs) Hyperchloremic
• Diet-induced hypokalemic nephropathy (cats) metabolic acidosis?
Yes No

Renal tubular acidosis Mineralocorticoid excess
(hyperaldosteronism)
Figure 5-11 Algorithm for the clinical approach to hypokalemia. (Drawing by Tim Vojt.)

BOX 5-1 Causes of Hypokalemia

Decreased Intake Urinary (FE K >4%-6%)
Alone unlikely to cause hypokalemia unless Chronic renal failure in cats
diet is aberrant Diet-induced hypokalemic nephropathy in cats
Administration of potassium-free (e.g., 0.9% NaCl, 5% Distal (type I) renal tubular acidosis (RTA)
dextrose in water) or deficient fluids (e.g., lactated Proximal (type II) RTA after NaHCO 3 treatment
Ringer’s solution over several days) Postobstructive diuresis
Bentonite clay ingestion (e.g., cat litter) Dialysis
Translocation (ECF ! ICF) Mineralocorticoid excess
Alkalemia Hyperadrenocorticism
Primary hyperaldosteronism (adenoma,
Insulin/glucose-containing fluids
adenocarcinoma, hyperplasia)
Catecholamines
Drugs
Hypothermia
Loop diuretics (e.g., furosemide, ethacrynic acid)
Hypokalemic periodic paralysis (Burmese cats)
Thiazide diuretics (e.g., chlorothiazide,
Albuterol overdosage
hydrochlorothiazide)
Increased Loss Amphotericin B
Gastrointestinal (FE K <4%-6%) Penicillins
Vomiting of stomach contents Unknown mechanism
Diarrhea Rattlesnake envenomation
was used in a dog with hypoadrenocorticism to assess the Effects of Potassium Depletion on
contribution of concurrent trimethoprim administration Acid-Base Balance
on the observed hyperkalemia. 166 The causes of hypoka-
Hypokalemia often is said to be associated with metabolic
lemia are listed in Box 5-1, and the diagnostic approach to
alkalosis, but early studies used diuretics or mineralo-
hypokalemia is presented in Figure 5-11.
corticoids to induce potassium depletion. These methods