Hypercalcaemia

Question 1

What is involved in the regulation of calcium?

Answer 1

• PTH (neg feedback by iCa)
• Calcitriol (promoted by PTH, inhibited by FGF23)
• Calcitonin

Question 2

What are the possible causes of hypercalcaemia?

Answer 2

• Increased PTH activity: primary hyperparathyroidism
• Increased Vit D activity: dietary/ toxin
• Osteolysis: local destruction of bone
• Hypoadrenocorticism

Question 3

What is PTHrP?

Answer 3

• PTH related protein

- Produced by cartilage, bone, muscle, epithelium, CNS

Question 4

List some differential diagnoses for hypercalcaemia

Answer 4

• Parathyroid adenoma
• Parathyroid hyperplasia
• Vit D excess
• Osteolysis
• Raisin toxicity

Question 5

What are the causes of total hypercalcaemia in dogs?

Answer 5

• Malignancy (most common)
• Hypoadrenocorticism
• Primary hyperparathyroidism
• Chronic renal failure
• Vit D toxicosis
• Granulomatous disease(least common)

Question 6

What are the causes of hypercalcaemia in cats?

Answer 6

• Idiopathic hypercalcaemia (most common)
• Renal failure
• Malignancy
• Primary hyperparathyroidism (least common)

Question 7

What are the causes of hypercalcaemia in horses?

Answer 7

-Chronical renal failure (most common)
-Vit D toxicosis
-Hypercalcaemia of malignancy
Primary hyperparathyroidism (least common)

Question 8

What are the clinical signs of hypercalcaemia?

Answer 8

• PU/PD (antagonism of ADH)
• Weakness
• Depression (decreased excitability of nervous tissue)
• Anorexia
• Constipation (decrease in the excitability of GI smooth muscle)
• Muscle twitching, shivering, seizures
• Bradycardia
• SOFT TISSUE MINERALISATION

Question 9

How do you diagnose hypercalcaemia?

Answer 9

• Review history= focus on diet and access to vit D
• Look at signalment
• Clinical exam- check lymph nodes, anal sac masses, angiostrongylus

Question 10

Discuss how the total calcium, iCa and phosphorus concentrations in blood would be affected in PTH/ PTHrH excess cases

Answer 10

• Total calcium= increase
• ICa= increasd
• Phosphorus= decreased

Question 11

Discuss how the total calcium, iCa and phosphorus concentrations in blood would be affected in Vit D excess cases

Answer 11

• Total calcium= elevated
• iCa= elevated
• Phosphrus= elevated

Question 12

What are the clinical signs of soft tissue mineralisation?

Answer 12

-Vomiting, anorexia, lethargy
PU/PD
-Acute renal failure
-Death
-Seizures

Question 13

FACTSHEET

Answer 13

Need to distinguish between PTH dependant and PTH independent hypercalcaemia (if calcium stays high when PTH is low= independent)

Question 14

What affects does hypoadrenocorticism normally have on calcium levels?

Answer 14

Normally only raises total calcium= ionised calcium usually remains normal

Question 15

Describe idiopathic hypercalcaemia

Answer 15

• Occurs in young to middle ages cats
• Phosphorus is normal
• Intact PTH normal or lowered
• PTHrP undetectable
• Vit D3 normal
• Both total and ionised calcium elevated

Question 16

What PTH concentration would you expect to see in an animal with secondary renal hyperparathyroidism?

Answer 16

Either lowered ICa or normal

whereas in primary hyperparathyroidism you expect to see increased calcium