Hyperkalemia in neonatal diarrheic calves depends on the degree of dehydration and the cause of the metabolic acidosis but does not require the presence of acidemia

Abstract

Hyperkalemia is a clinically important electrolyte imbalance in neonatal diarrheic calves that has previously been associated with skeletal muscle weakness and life-threatening cardiac arrhythmias. The aim of the present retrospective analysis was to identify risk factors for hyperkalemia in a convenience sample of 832 calves (≤ 21 d of age) with a clinical diagnosis of diarrhea admitted to a veterinary teaching hospital. Plasma potassium concentrations were most closely associated with parameters of dehydration and renal function such as serum creatinine [Spearman correlation (rs) = 0.61], urea (rs = 0.51), and inorganic phosphorus concentrations (rs = 0.64). Plasma potassium concentrations were weakly associated with venous blood pH (rs = -0.21). Although venous blood pH was not predictive in a multivariate linear regression analysis, the odds of having hyperkalemia (>5.8 mmol/L) in acidemic calves was found to be 8.6 times as high as in nonacidemic calves [95% confidence interval (CI): 4.8-15.4]. However, the presence of hyperkalemia depended on the nature of an existing acidosis, and the odds for the presence of hyperkalemia in acidemic calves with hyper-D-lactatemia (>3.96 mmol/L) were only 0.15 times as high as in acidemic calves with normal D-lactate concentrations (95% CI, 0.11-0.22). Acidemia in hyperkalemic diarrheic calves was associated with hyponatremia and increased concentrations of inorganic phosphorus, L-lactate, and unidentified strong anions that presumably included uremic anions such as sulfate. We conclude that hyper-D-lactatemia in neonatal diarrheic calves is not usually associated with elevated plasma potassium concentrations. Application of the simplified strong ion acid-base model indicated that dehydration is an important contributor to the pathogenesis of hyperkalemia and acidemia in neonatal calves with diarrhea.

Effect of Intravenous Small‐Volume Hypertonic Sodium Bicarbonate, Sodium Chloride, and Glucose Solutions in Decreasing Plasma Potassium Concentration in Hyperkalemic Neonatal Calves with Diarrhea

“…A similar increase after administration of sodium bicarbonate was not observed for D‐lactate in the present study. However, it needs to be emphasized that D‐lactate concentrations of most calves were within an established reference range for bucket‐fed calves of ≤3.96 mmol/L,66 which is in agreement with our previous findings that hyperkalemia in diarrheic calves is rarely associated with D‐lactic acidosis 4, 8. However given the fact that D‐lactate is only produced in minimal amounts in the methylglyoxal pathway in mammals,67 a therapeutic effect on D‐lactate concentrations could still be expected.…”

“…Based on anticipated mean and SD values for the plasma potassium concentration of 7.45 ± 1.28 mmol/L for the studied population based on data from 234 hyperkalemic calves of a previously published study,4 an alpha of 0.05 and a group size of 7, we calculated the power of the study to be 0.80.…”

“…However, recent studies indicate that hyperkalemia in diarrheic calves is dependent on the nature of the existing acidosis but not on acidemia per se, with D‐lactic acidosis being rarely associated with increased plasma potassium concentrations ( c K). More importantly, the c K in diarrheic calves is most closely associated with clinical and laboratory indices of dehydration, indicating that a decrease in renal glomerular filtration rate plays a central role in the development of a hyperkalemic state 4, 8…”

Risk Factors for the Development of Hypokalemia in Neonatal Diarrheic Calves

“…Classic papers stated that a 0.1 unit reduction in venous blood pH results in an increase of plasma K + of 0.3–0.5 mmol/L23 or 0.6 mmol/L 21. However, it was recently reported8 that this linear interrelation does not reflect the situation in diarrheic calves and that the presence of hyperkalemia depended on the nature of an existing acidosis but more importantly on the degree of dehydration. It was found that the presence of d ‐lactataemia in acidemic calves resulted in significantly lower odds for hyperkalemia but significantly higher odds for the presence of hypokalemia 8.…”

“…However, recent research has shown that dehydration and concomitant impairment of renal function represents an important mechanism in the pathogenesis of hyperkalemia in such animals. Additionally, the presence of hyperkalemia was reported to be dependent on the nature of an existing acidosis in such that d ‐lactic acidosis is only rarely associated with a hyperkalemic state 7, 8…”