Hypercalcemia Hypocalcemia 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. Puerperal tetany-Eclampsia 2. Hypoparathyroidism 3. Renal failure 4. Pancreatitis 5. 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