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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