Hyperparathyroidism

Question 1

What is PTH secreted in response to?

Answer 1

low ionised Ca2+ levels

Question 2

What is the function of PTH

Answer 2

1. ↑ osteoclast activity - releasing Ca2+ + PO4 from bones
2. ↑ Ca2+ + ↓PO4 reabsorption in kidney
3. ↑ active 1,25-dihydroxyvitamin D3 - ↑ absorption of Ca2+ in intestine
   OVERALL EFFECT = ↑Ca2+ and ↓PO4

Question 3

What secretes PTH?

Answer 3

chief cells of parathyroid glands

Question 4

What causes primary HPTH?

Answer 4

Solitary parathyroid adenoma (80%)
Parathyroid hyperplasia (20%)

Question 5

How does primary HPTH present?

Answer 5

often asymptomatic!! found incidentally on tests

1. ↑ Ca2+ - weak, tired, depressed, thirsty, dehydrated but polyuric
2. Bone resorption - pain, fractures + osteopenia, osteoporosis
3. ↑ BP, check Ca2+ in HTN

Question 6

What investigations would u do in primary HPTH?

Answer 6

1. ↑ Ca2+ and PTH (↑ or normal)
2. ↓ PO4
3. 24hr urinary Ca2+

Question 7

What test would u do once a diagnosis is confirmed?

Answer 7

DEXA scan

Question 8

What can be seen on imaging?

Answer 8

Skull XR - pepper pot skull

Question 9

What is the treatment of primary HPTH?

Answer 9

1. Increase fluid intake to prevent stones
2. Avoid thiazides + high ca2+ and vit D intake
3. Excise adenoma/hyperplastic glands

Question 10

what are indications for surgery in primary HPTH?

Answer 10

high serum or urinary Ca2+
Bone disease 
Osteoporosis
Renal calculi 
reduced renal function

Question 11

What are the complications of primary HPTH?

Answer 11

HypoPTH
Recurrent laryngeal nerve damage-> hoarseness
Symptomatic reduced Ca2+

Question 12

what are the causes of secondary HPTH?

Answer 12

Poor vit D intake

CKD - RF

Question 13

What Ca2+ and PTH levels are seen in secondary HPTH?

Answer 13

low Ca2+

high PTH

Question 14

What is the treatment of secondary HPTH?

Answer 14

Correct causes
Phosphate binders: vit D
Cinacalcet if PTH >85

Question 15

What Ca2+ and PTH levels are seen in tertiary HPTH?

Answer 15

Raised Ca2+

Extra raised PTH

Question 16

What causes tertiary HPTH?

Answer 16

Prolonged secondary hyperPTH
glands act autonomously having undergone hyperplastic or adenomatous change
Causes raised Ca2+ from increased secretion of PTH unlimited from feedback control

Question 17

What are causes of malignant HPTH?

Answer 17

1. Parathyroid related protein is produced by some SCLC, breast and renal carcinomas
   Mimics PTH resulting in hypercalcaemia
2. Bone infiltration resulting in Ca2+ mobilisation (MM, 2o metastases in bone)

Question 18

What are the levels of PTH and Ca2+ seen in malignant HPTH?

Answer 18

PTH low as parathyroid related protein not detected

Raised Ca2+