Serum ionized calcium in dogs with chronic renal failure and metabolic acidosis.
BACKGROUND
Chronic renal failure (CRF) is a common disease in dogs, and many metabolic disorders can be observed, including metabolic acidosis and calcium and phosphorus disturbances. Acidosis may change the ionized calcium (i-Ca) fraction, usually increasing its concentration.


OBJECTIVE
In this study we evaluated the influence of acidosis on the serum concentration of i-Ca in dogs with CRF and metabolic acidosis.


METHODS
Dogs were studied in 2 groups: group I (control group = 40 clinically normal dogs) and group II (25 dogs with CRF and metabolic acidosis). Serum i-Ca was measured by an ion-selective electrode method; other biochemical analytes were measured using routine methods.


RESULTS
The i-Ca concentration was significantly lower in dogs in group II than in group I; 56% of the dogs in group II were hypocalcemic. Hypocalcemia was observed in only 8% of dogs in group II when based on total calcium (t-Ca) concentration. No correlation between pH and i-Ca concentration was observed. A slight but significant correlation was detected between i-Ca and serum phosphorus concentration (r = -.284; P = .022), as well as between serum t-Ca and i-Ca concentration (r = .497; P < .0001).


CONCLUSIONS
The i-Ca concentration in dogs with CRF and metabolic acidosis varied widely from that of t-Ca, showing the importance of determining the biologically active form of calcium. Metabolic acidosis did not influence the increase in i-Ca concentration, so other factors besides acidosis in CRF might alter the i-Ca fraction, such as hyperphosphatemia and other compounds that may form complexes with calcium.
Kogika
Marcia M
MM
School of Veterinary Medicine, Universidade de São Paulo, Departamento de Clíníca Médica, São Paulo-SP, Brazil. mmkogika@usp.br
Lustoza
Marcio D
MD
Notomi
Marcia K
MK
Wirthl
Vera A B F
VA
Mirandola
Regina M S
RM
Hagiwara
Mitika K
MK
D000140:Acidosis, Lactic / Q000097:blood / Q000662:veterinary*; D000375:Aging; D000818:Animals; D002118:Calcium / Q000097:blood*; D004283:Dog Diseases / Q000097:blood*; D004285:Dogs; D006934:Hypercalcemia / Q000662:veterinary; D006996:Hypocalcemia / Q000662:veterinary; D007676:Kidney Failure, Chronic / Q000097:blood / Q000662:veterinary*
D002118:Calcium