Disorders of Calcium Homeostasis Flashcards
Where is the majority of the bodys calcium?
Bone
What does PTH do?
Raise serum calcium levels
Activates osteoclasts
Promotes calcium reabsorption
What is Vitamin D essential for?
GI uptake of calcium
What does Calcitonin do?
Lower serum calcium levels
Inhibits osteoclasts
Inhibits calcium reabsorption
What do osteoclasts do?
Release stored calcium
Part of the macrophage family
What is ionized calcium (iCa)?
The metabolically active portion
Defines true hypo- or hypercalcemia
What is protein bound calcium?
Mostly bound to albumin
Influenced by acid-base status
What defines true hyper- or hypo-calcemia?
Ionized calcium
What are the three mechanisms for hypercalcemia?
Excessive vitamin D activity
Excessive PTH activity
Excessive direct osteolytic activity
What are the most common differentials for canine hypercalcemia?
TUMORS
Drugs
Hyperparathyroidism
Granulomatous
What are the most common differentials for feline hypercalcemia?
IDIOPATHIC
Tumors
Renal
Hyperparathyroidism
Spurious
What are the three common presentations for hypercalcemia patients?
They come in sick from their underlying disease
They come in with signs reflecting increased calcium
You stumble across hypercalcemia during a wellness visit (cats)
What is the most common sign of hypercalcemia in the canine patient?
PU/PD
What is the most common sign of hypercalcemia in the feline patient?
ADR or dysuria from urolithiasis
When would you expect to see tissue mineralization?
Calcium x Phosphorus > 70
What would you expect to see with mild hypercalcemia (tCa < 13 mg/dl)?
Compromised ability to concentrate urine (dogs)
Increased risk of urolithiasis from calcium oxalate stone formation
GI issues (primarily cats)
What would you expect to see with moderate hypercalcemia (tCa 13-15 mg/dl)?
Mild signs
Renal damage (depending on phosphorus)
Possibly triggers pancreatitis (dogs)
Personality change
What would you expect to see with severe hypercalcemia (tCa > 15 mg/dl)?
Decreased neuromuscular excitability
Cardiac arrhythmias
What is the most common cause of hypercalcemia in dogs?
Hypercalcemia of malignancy / humoral hypercalcemia