Transcript Calcium
Calcium Hypercalcemia Hypocalcemia Calcium • 99% of the bodies calcium is in the bone in calcium phosphate compounds Calcium • Calcium ions serve many important roles in the body. • Components of bone and teeth • Responsible for the excitation and contraction of muscle cells • Important is regulating cardiac function • Required for nerve function • Activates metabolic enzymes • Serves as a cofactor for several blood-clotting proteins Calcium Regulation • Calcium homeostasis Total blood calcium is usually 10 mg/dl Ionized Calcium • Ionized calcium is considered the biologically active form of calcium and is the component that regulates the secretion of PTH. • Total calcium is made up of three components :protein bound calcium, ionized calcium and calcium that is complexed with other anions such as phosphate, citrate, bicarbonate and lactate Thyroid Parathyroid Parathyroid Hormone PTH • Parathyroid glands are found in all air-breathing vertebrates • The parathyroid glands act to increase serum calcium via production of parathyroid hormone (PTH). • Parathyroid gland cells have receptors for ionized Calcium that regulate secretion of PTH in a tight negative-feedback relation. • Small increases in ionized calcium inhibit secretion of PTH and small decreases of ionized calcium prompt the release of PTH PTH Parathyroid Hormone • The primary function of PTH is to elevate the serum ionized Ca++ concentration. • This is accomplished by • 1. Stimulating bone resorption (dissolution) • 2. Increase the Reabsorption of Ca++ in the kidneys • 3. Decrease renal Phosphate reabsorbtion • 4. Stimulate activation of Vit D in the kidneys • Vit D increases the efficiency of Ca++ absorption in the small intestine Hypercalcemia • Calcium is intimately involved with muscle and nerve function • The biologically active form of calcium is the ionized portion • Ionized calcium has a negative feedback on parathyroid hormone (PTH) production • Normal total blood calcium levels are 10mg/dl • Clinical signs appear around 15mg/dl Hypercalcemia Symptoms • • • • • • • Often related to underlying disease Lethargy Weakness PU/PD Cardiac irregularities Anorexia +/- seizures and muscle twitching Hypercalcemia Etiology • • • • • • • • Laboratory error Hypercalcemia of malignancy Addison’s disease (30-40%) Primary hyperparathyroidism Granulomatous disease (Blasto, Cocci) Cholecalciferol rodenticide poisoning Bone cancer Bone infection (osteomyelitis) Parathyroid Hormone Analysis • Measurement of PTH currently is accomplished using commercially available immunoradiometric assays (IRMAs) for human PTH. • PTH degrades quickly . Samples are usually frozen. Large commercial labs and the University of Michigan can run the analysis Hypercalcemia Diagnosis • Total Calcium is routinely measured on chemistry panels. Hypercalcemia Malignant Causes • >40% of all cases of hypercalcemia in dogs and <30% in cats are caused by malignant tumors. • Humoral Hypercalcemia of Malignancy (HHM)Parathyroid hormone related protein. (PTHrP) • 1. Lymphosarcoma (especially medianstinal forms) • 2. Adenocarcinoma of the anal sacs • 3. Multiple Myeloma Hypercalcemia Hyperparathyroidism • Usually caused by adenomas of one of the parathyroid glands • Moans, groans, stones and bones Hyperparathyroidism Treatment • Treat and lower the hypercalcemia • Surgically remove all enlarged thyroid glands • Hypocalcaemia commonly occurs after surgery Hypercalcemia Treatment • 1. Detecting and treating the underlying cause • 2. Fluid therapy preferably with .9%NaCl • 3. Furosemide (lasix) diuretic • 4. Prednislone reduces calcium reabsorbtion • 5. Calcitonin (thyroid) Hypercalcemia Prognosis • 1. Primary Hyperparathyroidism • 2. Malignant Hypercalcemia • 3. Assorted diseases Hypocalcemia • A common biochemical abnormality in dogs and cats caused by numerous conditions. Common conditions associated with Hypocalcemia are puerperal tetany, iatrogenic hypoparathyroidism and primary hypoparathyroidism Hypocalcemia • • • • • 1. 2. 3. 4. 5. Puerperal tetany-Eclampsia Hypoparathyroidism Renal failure Pancreatitis Antifreeze, ethylene glycol toxicity Hypocalcemia Symptoms • Tetany, Stiff gait, muscle fasciculations and generalized tremors • Facial rubbing and pawing • Generalized seizures • Drooling (cats) • Hyperthermia** • Panting and Hyperventilation** • Puerperal tetany usually occurs postpartum but can occur near the end of pregnancy Laboratory Findings • Physical Examination • Medical History-Recent Thyroid surgery • Low Total blood calcium