Presumptive increase in protein-bound serum calcium in a dog with multiple myeloma

• Published in: Veterinary clinical pathology 2009-03, Vol.38 (1), p.87-90
• Main Authors: Tripp, Chelsea D, Bryan, Jeffrey N, Willis, Tamara B
• Format: Article
• Language: English
• Subjects: Animals; blood chemistry; blood plasma; Calcium; Calcium - blood; case studies; dietary minerals; dog; dog diseases; Dog Diseases - blood; Dog Diseases - metabolism; Dogs; globulins; hypercalcemia; Hypercalcemia - blood; Hypercalcemia - veterinary; hyperglobulinemia; Male; monoclonal gammopathy; multiple myeloma; Multiple Myeloma - blood; Multiple Myeloma - metabolism; Multiple Myeloma - veterinary; myeloma; neoplasms; pets; protein binding; radiography; signs and symptoms (animals and humans); spleen; splenic multiple myeloma; thrombocytopenia; urine
• ISSN: 0275-6382; 1939-165X
• DOI: 10.1111/j.1939-165X.2008.00102.x

: An 11‐year‐old male castrated Australian Shepherd was presented with a history of lethargy, panting, and weight loss for 1 month. Physical examination revealed a moderately enlarged spleen. Laboratory abnormalities included thrombocytopenia and marked hypercalcemia, with hyperglobulinemia, hypoalbuminemia, and a monoclonal spike in the β‐globulin region on serum protein electrophoresis. Serum total calcium concentration was markedly increased (16.5 mg/dL, reference interval 8.9–11.4 mg/dL) but ionized calcium concentration (1.39 mmol/L) was within the reference interval (1.25–1.45 mmol/L). Isosthenuria was noted, but the dog was not polyuric or polydipsic. Serum parathyroid hormone concentration was within reference limits and parathyroid hormone‐related peptide concentration was 0 pmol/L. Radiographic findings were largely unremarkable. Results of cytologic evaluation of a fine‐needle aspirate specimen from the spleen indicated plasma cell neoplasia. Based on the results of the electrophoresis, splenic aspirates, radiographs, and hypercalcemia, a diagnosis of splenic multiple myeloma was made. The marked hypercalcemia, normal ionized calcium and parathyroid hormone concentrations, and lack of osteolytic lesions indicated a presumptive increase in protein‐bound serum calcium, likely due to binding to molecules of the paraprotein (M protein). Protein binding of calcium in dogs with multiple myeloma should be considered as a potential mechanism of elevated total serum calcium concentration.