Serum ionized calcium in dogs with chronic renal failure and metabolic acidosis

Authors

  • Marcia M. Kogika,

    1. From the School of Veterinary Medicine, Universidade de São Paulo, Departamento de Clínica Médica, São Paulo-SP, Brazil. Presented at the 27th Congress of the World Small Animal Veterinary Association, Granada, Spain, October 3–6, 2002. Corresponding author: Marcia Mery Kogika (mmkogika@usp.br)
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  • Marcio D. Lustoza,

    1. From the School of Veterinary Medicine, Universidade de São Paulo, Departamento de Clínica Médica, São Paulo-SP, Brazil. Presented at the 27th Congress of the World Small Animal Veterinary Association, Granada, Spain, October 3–6, 2002. Corresponding author: Marcia Mery Kogika (mmkogika@usp.br)
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  • Marcia K. Notomi,

    1. From the School of Veterinary Medicine, Universidade de São Paulo, Departamento de Clínica Médica, São Paulo-SP, Brazil. Presented at the 27th Congress of the World Small Animal Veterinary Association, Granada, Spain, October 3–6, 2002. Corresponding author: Marcia Mery Kogika (mmkogika@usp.br)
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  • Vera A. B. F. Wirthl,

    1. From the School of Veterinary Medicine, Universidade de São Paulo, Departamento de Clínica Médica, São Paulo-SP, Brazil. Presented at the 27th Congress of the World Small Animal Veterinary Association, Granada, Spain, October 3–6, 2002. Corresponding author: Marcia Mery Kogika (mmkogika@usp.br)
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  • Regina M. S. Mirandola,

    1. From the School of Veterinary Medicine, Universidade de São Paulo, Departamento de Clínica Médica, São Paulo-SP, Brazil. Presented at the 27th Congress of the World Small Animal Veterinary Association, Granada, Spain, October 3–6, 2002. Corresponding author: Marcia Mery Kogika (mmkogika@usp.br)
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  • Mitika K. Hagiwara

    1. From the School of Veterinary Medicine, Universidade de São Paulo, Departamento de Clínica Médica, São Paulo-SP, Brazil. Presented at the 27th Congress of the World Small Animal Veterinary Association, Granada, Spain, October 3–6, 2002. Corresponding author: Marcia Mery Kogika (mmkogika@usp.br)
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Abstract

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). Conclusion: 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.

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