Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
Calcium is crucial to many physiologic processes, including enzymatic functions and the electrical activity of muscles and nerves.1,2 Typically, the calcium status of animals is assessed by the measurement of total serum or plasma calcium concentrations. The nonionized portion of this total calcium consists of calcium in complexed or protein-bound form. Ionized calcium is the biologically active form of calcium. It is normally kept within a narrow range by a variety of homeostatic mechanisms.3 Measurement of ionized calcium may provide a more accurate assessment of the calcium status of an animal.
Ionized calcium was measured in the plasma of 30 healthy green iguanas (Iguana iguana) to establish a normal range. The animals were housed outside at two separate locations in northern Florida. Blood samples were collected during July and August. Health was assessed by physical examination, complete blood count, and plasma biochemistry profile. Plasma calcium, glucose, phosphorus, uric acid, total protein, albumin, globulin, aspartate transaminase, sodium, potassium, ionized calcium, total carbon dioxide, and pH were measured. The average value of ionized calcium measured in whole blood was 1.47±0.10 mmol/L. The average plasma calcium was 12.8±0.93 mg/dl.
1. Capen CC, SL Martin. 1982. Calcium regulating hormones and diseases of the parathyroid glands. In: Textbook of Veterinary Internal Medicine. WB Saunders, Co, Philadelphia, Pennsylvania, pp. 1550–1592.
2. Chew DJ, DJ Meuten. 1982. Disorders of calcium and phosphorus metabolism. In: Vet Clin North Am (Small Anim Pract). 12:411–438.
3. Rose BD. 1994. Effects of hormones on renal function. In: Clinical Physiology of Acid-Base and Electrolyte Disorders. McGraw-Hill, Inc, New York, New York, pp. 184–198.