Muscle Potassium Content and Potassium Gluconate Supplementation in Normokalemic Cats With Naturally Occurring Chronic Renal Failure

Abstract

Muscle potassium content and supplementation with potassium gluconate were evaluated in normokalemic cats with chronic renal failure (CRF). Affected cats received standard medical therapy for renal failure and either placebo (sodium gluconate) or potassium gluconate. At the beginning of the study and after 6 months of supplementation, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were estimated using 3H-inulin and '4C-tetraethylammonium bromide (TEA) clearances. Muscle potassium content was determined in biopsy specimens using atomic absorption spectroscopy. Muscle biopsy samples obtained from cats with CRF before treatment had significantly lower muscle potassium content than did those from normal control cats. Over the 6-month period of supplementation, muscle ats with chronic renal failure (CRF) are presented to C veterinarians for evaluation of chronic weight loss, anorexia, polyuria, polydipsia, and vomiting. In retrospective studies, hypokalemia occurred in 20% t o 30% of cats with CRF,'.' and CRF was the most common disease association in a survey of cats with hypokalemia.' Potassium is predominantly an intracellular cation, and approximately 95% of total body potassium resides in the skeletal muscles. Consequently, serum potassium concentration may not reflect total body potassium status, especially in the early stages of potassium depletion. The purposes of this study were to compare muscle potassium content in normokalemic cats with CRF and in normal control cats, and to determine whether supplementation of normokalemic cats with CRF using potassium gluconate would have beneficial effects over a 6-month period. Materials and Methods Criteria for Inclusion in the StudyClient-owned cats with spontaneously occurring CRF were eligible for entry in the study if the following criteria were met: (1) From the Departments of Veterinary Clinical Sciences (Theisen, DiBurtoh, Chew, Btlffingtonj and Veterinary Biosciences (Rudin) clinical evidence of small, irregular kidneys based on abdominal palpation, routine abdominal radiography, or abdominal ultrasonography; (2) serum creatinine concentration (SCr) of 2.0 to 7.0 mg/dL; (3) normal serum potassium concentration (>3.4 mEq/L); and (4) absence of urinary tract infection based on bacterial culture of urine obtained by cystocentesis. Informed consent of the owners was obtained, and cats were required to be available for study over a 6-month period. Renal biopsy specimens were not obtained from cats with CRF in an attempt to facilitate enrollment of client-owned cats in the study. Based on these criteria, 12 cats were enrolled over a 2-year period. Control cats for muscle potassium content determinations consisted of 13 middle-aged experimental cats (7 males, 6 females), determined to be normal based on physical examination, serum chemistry, and renal histopathology.

Potassium Disorders

“…In cats, hypokalemic myopathy typically is associated with chronic renal disease and poorly regulated diabetes mellitus. 2,8,12 In the myocardial cell, a high intracellular/extracellular potassium concentration ratio induces a state of electrical hyperpolarization leading to prolongation of the action potential. 14 More recently feline hyperaldosteronism as a result of aldosteronoma and adrenocortical hyperplasia has been described, although a diagnostic workup for these conditions is only indicated if the more common etiologies are not present.…”

Retrospective study of the efficacy of oral potassium supplementation in cats with kidney disease

“…7 Therefore, it is thought that serum potassium concentrations may not be representative of intracellular potassium concentrations as normokalemic cats with CKD have been demonstrated to have lower muscle potassium concentrations than normal control cats. 6 Clinical signs of moderate-to-severe hypokalemia can include muscle weakness, particularly cervical ventroflexion, polyuria and polydipsia, tachycardia, constipation and anorexia. 4 Although hypokalemia has not been shown to be a risk factor for disease progression or outcome in CKD cats, 8,9 studies in CKD cats have demonstrated improvement in renal function when normokalemia was restored with potassium supplementation.…”

Avaliação do cálcio sérico ionizado em gatos sadios e em gatos com insuficiência renal crônica

“…A hipercalcemia, conseqüente à IRC pode decorrer da diminuição da eliminação de cálcio e de PTH, bem como de seus metabólitos, pelos rins devido a baixa taxa de filtração glomerular, como também pelo aumento na formação de complexos cálcicos séricos estimulado pelo PTH, pela diminuição da sensibilidade da paratireóide ao cálcio sérico e do aumento da sensibilidade dos receptores intestinais para calcitriol, devido ao baixo nível de calcitriol sérico MEUTEN, 1982;KRUGER et al, 1996). , 1986;POLZIN et al, 2001;THEISEN et al, 1997). No presente estudo, a freqüência de hipopotassemia em 15,8% dos casos de IRC foi menor quando comparada aos relatos anteriores, possivelmente pelo fato de que alguns animais encontravam-se em terapia de suplementação oral de potássio (gluconato de potássio).…”

“…De acordo com um estudo realizado por Theisen et al (1997), a administração de gluconato de potássio assegura a manutenção de níveis séricos estáveis de potássio, entretanto, a presença de valores séricos normais de potássio não exclui a possibilidade de défice orgânico de potássio, uma vez que gatos com IRC, normocalêmicos, apresentavam valores diminuídos de potássio muscular, quando comparados com gatos sadios.…”