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 HormonePTH

• 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

PTHParathyroid 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

HypercalcemiaSymptoms

• Often related to underlying disease

• Lethargy

• Weakness

• PU/PD

• Cardiac irregularities

• Anorexia

• +/- seizures and muscle twitching

HypercalcemiaEtiology

• 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 HormoneAnalysis

• 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

HypercalcemiaDiagnosis

• Total Calcium is routinely measured on chemistry panels.

HypercalcemiaMalignant 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

HypercalcemiaHyperparathyroidism

• Usually caused by adenomas of one of the parathyroid glands

• Moans, groans, stones and bones

HyperparathyroidismTreatment

• Treat and lower the hypercalcemia

• Surgically remove all enlarged thyroid glands

• Hypocalcaemia commonly occurs after surgery

HypercalcemiaTreatment

• 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)

HypercalcemiaPrognosis

• 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

HypocalcemiaSymptoms

• 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