Page 121 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Disorders of Potassium: Hypokalemia and Hyperkalemia 111

• Platelet count > 1,000,000/µL?
• Hemolysis of HK RBC (e.g., Akita, Shiba)?
Yes No

Pseudohyperkalemia Drug administration?
• ACE inhibitors • NSAIDs • Cyclosporin A,
• AII receptor blockers • Heparin tacrolimus
• K + -sparing diuretics • Trimethoprim
Yes No

Consider iatrogenic hyperkalemia, especially when
drug administration is combined with decreased
renal function or potassium supplementation
Thrombolytic therapy? Translocation of K+ ICF Æ ECF
Yes No
Reperfusion injury Hyperglycemia, glucosuria, ketonuria?
Yes No
Diabetic ketoacidosis Azotemia?
Yes No

Cancer chemotherapy? Drug administration?
Yes No Yes No

Acute tumor • Acute mineral acidosis (e.g., NH4Cl)
lysis syndrome • b-blockers
• Cardiac glycosides
• Lysine or arginine infusion
Large bladder? Unable to urinate?
• Hypoadrenocorticism-like syndrome with GI losses
(e.g., trichuriasis, salmonellosis)
Yes No
• Pleural or peritoneal effusion (third space loss)
• Late pregnancy
Urethral obstruction Trauma?
Yes No
Ruptured bladder Pre and post-ACTH
cortisol concentrations
< 1.0 µg/dL?
Yes No
Hypoadrenocorticism Oliguric acute renal failure
Figure 5-13 Algorithm for the clinical approach to hyperkalemia. (Drawing by Tim Vojt.)

renal disease have reduced ability to tolerate an acute occurred commonly in a population of dogs with natu-
potassium load and may require 1 to 3 days to reestablish rally occurring chronic renal disease and responded well
external potassium balance when intake of potassium is in 18 of 26 dogs managed by feeding them a potas-
abruptly increased. Dogs with experimentally induced sium-reduced, home-prepared diet. 184
renal disease demonstrate decreased ability to excrete a Oliguria or anuria with hyperkalemia is more likely to
potassium load. In the first 5 hours after a potassium load, occur in acute renal failure (e.g., ethylene glycol ingestion),
dogs with experimentally induced renal disease excreted but these findings may be observed terminally in chronic
30% to 37% of administered potassium, whereas control renal failure. Acute renal failure with oliguria or anuria is
dogs excreted 56% to 67%. 24,25 Kaliuresis was blunted associatedwithhyperkalemiaforseveralreasons.First,there
in the dogs with remnant kidneys despite exaggerated has been insufficient time for renal adaptation to nephron
hyperkalemia and increased secretion of aldosterone, loss, as occurs with chronic renal failure. Severe reductions
and approximately 24 hours were required for complete in GFR and urine output result in inadequate distal tubular
excretion of the potassium load. Episodes of moderate flow for effective urinary excretion of potassium. Finally,
(>5.3 mEq/L) or severe (6.5 mEq/L) hyperkalemia increased release of potassium from tissues during this