A case of hyporeninemic hypoaldosteronism in the dog.

A 13-year-old female spayed Yorkshire Terrier, weighing 6.1 kg, was referred to the Internal Medicine Service of the Animal Medical Center for hypercalcemia and hyperkalemia. Active medical problems included mild stable azotemia of 11 months duration (International Renal Interest Society Stage II, http://www.iris-kidney.com) and collapsing trachea. The owner also reported a lifelong history of infrequent seizures. Medical treatments at presentation included hydrocodone (0.625mg PO), aminophylline (50mg PO), aluminum hydroxide (2.5mL PO q12h), PetTinic (2.5mL PO q12h), and lactated Ringer’s solution (150mL SC q24h). The dog was receiving a home-cooked diet consisting of ground turkey, rice, and various vegetables. The diet was not prescribed by a veterinarian for a specific medical indication. The dog was obese, with a body condition score of 8 of 9, and had a persistent honking cough during examination, which precluded thoracic auscultation. The remainder of the physical examination was unremarkable. During this initial evaluation, blood was drawn for serum biochemistry, including venous blood gas and plasma electrolyte concentrations, and ACTH stimulation test. The dog was discharged without adjustments in management plan pending review of the laboratory results. Serum biochemistry abnormalities (all reference ranges are for adult dogs) included increased alanine transferase (ALT) activity (75U/L; reference range, 5– 60U/L), increased creatine kinase (CK, 232U/L; reference range, 10–200U/L), increased urea nitrogen concentration (blood urea nitrogen [BUN], 71mg/dL; reference range, 7–27mg/dL), increased creatinine concentration (2.0mg/dL; reference range, 0.4–1.8mg/dL), hypercalcemia (tCa, 12.7mg/dL; reference range, 8.2– 12.4mg/dL), hyperkalemia (K, 7.5mEq/L; reference range, 4.0–5.6mEq/L), and decreased sodium/potassium ratio (Na/K, 19.9; reference range, 27–40). Evaluation of venous blood gases and plasma electrolyte concentrations indicated normal plasma ionized calcium (iCa) concentration (4.8mEq/L; reference range, 4.8–5.3mEq/L) and pH (7.41; reference range, 7.35– 7.45). Hyperkalemia (K, 5.94mEq/L; reference range, 3.50–5.30mEq/L) also was present. Hypocortisolism was excluded because adequate serum cortisol concentrations were present at baseline and in response to ACTH stimulation (baseline, 8.6 mg/dL; reference range, 2.0–6.0mg/dL; post-ACTH, 31.1mg/dL; reference range, 6–22 mg/dL). Re-evaluation was performed 6 weeks later and the owner reported no new problems. Blood was obtained for serum biochemistry and parathyroid hormone (PTH) concentration. A voided urine sample was obtained for urinalysis, urine protein:creatinine ratio (UPC), and fractional electrolyte excretion. A cervical ultrasound examination was declined by the owner. Serum biochemistry abnormalities included increased ALT activity (84U/L), increased urea nitrogen concentration (BUN, 73mg/dL), increased creatinine concentration (2.2mg/dL), hyperglycemia (142mg/dL; reference range, 60–125mg/dL), hypercalcemia (tCa, 14.9mg/dL), increased bicarbonate (28mEq/L; reference range, 17–24mEq/L), hyperkalemia (K, 6.3mEq/L), and decreased Na/K (23.5). PTA concentration was increased (22.7 pmol/L; reference range, 2–13 pmol/L) with a concurrent slight increase in iCa concentration (1.47mmol/L; reference range, 1.25–1.45mmol/L). Urinalysis disclosed isosthenuria with proteinuria and an inactive sediment. The UPC was 7.3 (reference range, o1.0). Evaluation of fractional electrolyte excretion indicated excessive From the Miami Veterinary Specialists, Miami, FL (Kreissler) and the Animal Medical Center, New York, NY (Langston). The patient reported in this manuscript was seen at the Animal Medical Center, New York, NY. The manuscript has not been previously presented. Corresponding author: J. J. Kreissler, DVM, Miami Veterinary Specialists, 8601 Sunset Drive, Miami, FL 33143; e-mail: [email protected]. Submitted January 27, 2011; Revised April 17, 2011; Accepted May 3, 2011. Copyright r 2011 by the American College of Veterinary Internal Medicine 10.1111/j.1939-1676.2011.0741.x Abbreviations: