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37 Cards in this Set

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  • Back
Three substances that maintain calcium levels in the body
- Calcitonin
- Vitamin D
- PTH
3 organs where calcium regulation takes place
- Bone
- Kidney
- Intestines
3 effects of PTH on calcium
- Increased bone reabsorption
- Increased renal reabsorption
- Increased Vitamin D synthesis
Two roles of Vitamin D in calcium maintenance
- Enhanced reabsorption of Ca and P from intestine
- Decreased renal excretion of Ca
What is the primary hormone responsible for lowering Ca++ levels?
Calcitonin
Effects of an increase in Vitamin D on Ca and P levels
Increases both
Effects of an increase in Calcitonin on Ca and P levels
Decreases both
Effects of an increase in PTH on Ca and P levels
Increases Ca++, decreases P
How much of the calcium in blood is ionized on average?
50%
Which Calcium form is biologically active?
iCa
Effects of metabolic pH levels on iCa
Inverse
- Higher pH lowers iCa
Two test samples for Calcium measurement
- Serum (preferred)
- Plasma
What test sample should be avoided for Calcium measurement?
Any sample stored in a substance that chelates Ca++, such as EDTA.
4 values measured in a Calcium panel
- Total Ca++
- iCa
- PTH
- PTHrP
3 mechanisms of Calcium increase
- Increased mobilization from bone
- Increased absorption from intestine
- Decreased urinary excretion of calcium
What does the mnemonic, PARD IONS, for the disease states that cause hypercalcemia stand for?
P - Primary hyperparathyroidism
A - Addison's disease
R - Renal failure
D - Hypervitaminosis Vitamin D

I - Idiopathic
O - Osteolytic lesions
N - Neoplasia/nutrition
S - Schistosomiasis
4 conditions caused by hypercalcemia
- Soft tissue calcification
- PU/PD and hypothenosis
- Urinary calculi
- Neuromuscular signs
4 likely diagnosis' for extreme hypercalcemia
- Hypercalcemia of malignancy
- Primary hyperparathyroidism
- Hypervitaminosis D
- Schistosomiasis
Two tumors likely to cause hypercalcemia
- Lymphoma
- Adenocarcinoma of the anal sac
What should raise your suspicion of primary hyperparathyroidism induced hypercalcemia?
Hypercalcemia with a normal PTH level
- A 'normal' hypercalcemia would have a low PTH level due to negative feedback
Two sources of a vitamin D induced hypercalcemia
- Exogenous
- Endogenous (granulamatous disease)
Two likely diagnosis' for a mild hypercalcemia
- Hypoadrenocorticism
- Renal disease
Which species has a normal amount of calcium in their urine?
Horses
What is a mild increase in calcium in the urine due to renal disease common with?
Grape/raisin toxicity
Cause of renal secondary hyperparathyroidism
Decreased Vitamin D formation secondary to:
- Hyperphosphatemia
- Damaged tubular epithelial cells
What does the decrease in Vitamin D due to damaged tubular epithelial cells cause? (3)
- Decreased intestinal absorption of calcium
- Decreased resorption of bone
- Increased PTH due to decreased inhibition of PTH synthesis by Vitamin D
4 'other' causes of mild hypercalcemia
- Osteolytic lesions
- Young, growing dogs
- Thiazide diuretics
- Idiopathic
Causes of hypocalcemia as indicated by the mnemonic MATCHING DRAPES

MATCHING part
M - Malabsorption
A - Albumin decrease
T - Trauma, tumor lysis
C - Calcitonin, colic
H - Hypoparathyroidism
I - Infarct of parathyroid gland
N - Nutritional
G - GI disease (malabsorption), Grass Tetany
Causes of hypocalcemia as indicated by the mnemonic MATCHING DRAPES

DRAPES part
D - Drugs, diet, decreased Vitamin D
R - Renal failure
A - Albumin decrease
P - Pancreatitis, parathyroid atrophy
E - Ethylene glycol
S - sepsis (colic)
Clinical signs of hypocalcemia (4)
- Stiff gait (classical sign)
- Muscle tremors
- Seizures
- Weakness
What's the most common clinical sign of hypocalcemia in cattle?
Weakness
What is the most common cause of hypocalcemia by far?
Hypoalbuminemia
3 main mechanisms, aside from protein loss, that causes hypocalcemia
- Decreased PTH activity
- Inadequate intestinal absorption
- Excess urinary excretion
6 considerations for extreme hypocalcemia
PECAPA
- Primary hypoparathyroidism
- Ethylene glycol
- Cantharidin toxicity
- Acute pancreatitis
- Periparturient
- Artifact (EDTA)
Primary consideration for hypocalcemia in horses
Colic
How does ethylene glycol cause hypocalcemia?
Chelation due to oxalate crystals