Parathyroid & Calcium Metabolism

Question 1

What is the overall effect of parathyroid hormone?

Answer 1

To increase serum calcium and decrease serum phosphate

Question 2

What effect does PTH have on bone?

Answer 2

Increases bone turnover, by increasing osteoclast activity

Question 3

What effect does PTH have on reabsorption in the kidneys?

Answer 3

Increases reabsorption of calcium, decreases reabsorption of phosphate

Question 4

PTH increases the production of what in the kidneys?

Answer 4

Calcitriol (1, 25-dihydroxy-vitamin D3)

Question 5

What is the effect of calcitriol (1, 25- dihydroxy-vitamin D3)?

Answer 5

Increases calcium absorption from the gut

Question 6

What triggers the secretion of PTH from the parathyroid gland?

Answer 6

Low serum calcium levels

Question 7

What effect does a low serum calcium have on PTH levels?

Answer 7

Increased

Question 8

What effect does a high serum calcium have on PTH levels?

Answer 8

Decreased

Question 9

What other substance plays a synergistic role with PTH by increased calcium reabsorption from the kidneys and increasing bone turnover, but at a much slower rate?

Answer 9

Vitamin D3

Question 10

Where is calcitonin produced?

Answer 10

The parafollicular ‘C’ cells of the thyroid gland

Question 11

What is the effect of calcitonin?

Answer 11

Decrease serum calcium and phosphate

Question 12

What electrolyte is required in order to allow PTH release from the parathyroid glands?

Answer 12

Magnesium

Question 13

How are the features of hypercalcaemia typically remembered?

Answer 13

Bones, stones, groans and psychic moans

Question 14

What are some gastrointestinal features of hypercalcaemia?

Answer 14

Abdominal pain, vomiting, constipation, peptic ulcers

Question 15

What are some renal/urological features of hypercalcaemia?

Answer 15

Polyuria, polydipsia, renal stones

Question 16

What effect does hypercalcaemia have on bones, clinically?

Answer 16

Osteopenia/osteoporosis, and increased risk of fractures

Question 17

Patients with hypercalcaemia should always undergo what investigation to screen for osteoporosis?

Answer 17

DEXA bone scan

Question 18

What ECG change may be seen in individuals with hypercalcaemia?

Answer 18

Shortened QT interval

Question 19

What are the three causes of primary hyperparathyroidism?

Answer 19

Parathyroid adenoma (85%), parathyroid hyperplasia (15%), parathyroid carcinoma (< 1%)

Question 20

What are the three main causes of hypercalcaemia of malignancy?

Answer 20

Bony metastases, myeloma, ectopic production of PTH related peptide

Question 21

What are some malignancies which may result in the release of PTH related protein?

Answer 21

Squamous cell lung cancer, breast carcinoma, renal cell carcinoma

Question 22

What will the levels of PTH and calcium be in individuals with malignant hyperparathyroidism?

Answer 22

High calcium, low PTH (because PTH related protein doesn’t show up on the assay)

Question 23

When is acute treatment required for hypercalcaemia?

Answer 23

If calcium is > 3.5mmol/L or the patient is symptomatic

Question 24

What are the two main steps in the acute treatment of hypercalcaemia?

Answer 24

Rehydration and bisphosphonates

Question 25

How are patients with hypercalcaemia rehydrated?

Answer 25

4-6L of IV 0.9% saline are given over 24 hours

Question 26

What happens to phosphate levels in primary hyperparathyroidism?

Answer 26

Low

Question 27

What happens to ALP levels in primary hyperparathyroidism?

Answer 27

High

Question 28

Secondary hyperparathyroidism is a reactive increase in PTH production to compensate for hypocalcaemia. This is usually caused by one of what two things?

Answer 28

Chronic renal failure or vitamin D deficiency (osteomalacia)

Question 29

How should secondary hyperparathyroidism be treated?

Answer 29

Treat the underlying cause, give phosphate binders and vitamin D supplements

Question 30

For tertiary hyperparathyroidism to occur, hypersecretion of PTH for many years due to secondary hyperparathyroidism leads to the development of what?

Answer 30

Parathyroid hyperplasia

Question 31

What is some advice that can be given to patients with primary hyperparathyroidism if their case is mild or if surgery needs to be avoided?

Answer 31

Drink plenty fluids, avoid a high calcium/vitamin D intake, avoid thiazide diuretics

Question 32

If there is no obvious cause for hypercalcaemia then the underlying cause is most likely to be what?

Answer 32

Primary hyperparathyroidism

Question 33

What happens to PTH and calcium levels in primary hyperparathyroidism?

Answer 33

PTH high, calcium high

Question 34

What happens to PTH and calcium levels in secondary hyperparathyroidism?

Answer 34

PTH high, calcium low

Question 35

What happens to PTH and calcium levels in tertiary hyperparathyroidism?

Answer 35

PTH high, calcium high

Question 36

What are some drugs which may cause a high PTH and high calcium?

Answer 36

Lithium and thiazide diuretics

Question 37

What is the management option of choice for primary hyperparathyroidism?

Answer 37

Surgery

Question 38

What is the surgical management of choice for a parathyroid adenoma?

Answer 38

Parathyroidectomy of the affected gland

Question 39

What is the surgical management of choice for parathyroid hyperplasia?

Answer 39

Parathyroidectomy of all four glands, one gland is transplanted into the forearm

Question 40

Calcium levels should be monitored for how long after a parathyroidectomy?

Answer 40

14 days or more

Question 41

Parathyroid hyperplasia may occur as part of which two MEN syndromes?

Answer 41

MEN1 and MEN2A

Question 42

How is familial hypocalciuric hypercalcaemia inherited?

Answer 42

Autosomal dominant

Question 43

What is the most common feature of hypocalcaemia?

Answer 43

Paraesthesia (fingers, toes, peri-oral)

Question 44

What ECG change may be seen with hypocalcaemia?

Answer 44

Prolonged QT interval

Question 45

Chvostek's sign is seen individuals with hypocalcaemia. Describe this sign?

Answer 45

Tapping over the parotid gland causes facial muscles to twitch

Question 46

Trousseau's sign is seen in individuals with hypocalcaemia. Describe this sign?

Answer 46

Fingers draw together and wrist flexion occurs on inflation of a BP cuff

Question 47

A deficiency of what electrolyte can cause secondary hypoparathyroidism and hence hypocalcaemia?

Answer 47

Magnesium

Question 48

How is hypocalcaemia managed in the long term?

Answer 48

Oral calcium and vitamin D supplements

Question 49

What is the emergency treatment for hypocalcaemia?

Answer 49

10mls 10% calcium gluconate over 10 mins in 50ml saline or dextrose

Question 50

What are the two main causes of primary hypoparathyroidism?

Answer 50

Autoimmune or congenital

Question 51

Other than hypomagnesaemia, what are some potential causes of secondary hypoparathyroidism?

Answer 51

Radiation or surgery to the thyroid/parathyroid gland

Question 52

What happens in pseudohypoparathyroidism?

Answer 52

There is failure of the target cells to respond to PTH

Question 53

Short 4th + 5th metacarpals, a round face, short stature, calcified basal ganglia and low IQ are signs of what condition?

Answer 53

Pseudohypoparathyroidism

Question 54

What happens to PTH and calcium levels in primary hypoparathyroidism?

Answer 54

Low PTH, low calcium

Question 55

What happens to PTH and calcium levels in secondary hypoparathyroidism?

Answer 55

Low PTH, low calcium

Question 56

What happens to PTH and calcium levels in pseudohypoparathyroidism?

Answer 56

High PTH, low calcium

Question 57

What happens to PTH and calcium levels in pseudopseudohypoparathyroidism?

Answer 57

Both normal

Question 58

What is pseudopseudohypoparathyroidism?

Answer 58

The morphological features of pseudohypoparathyroidism but with normal biochemistry

Question 59

What is the cause for both pseudo and pseudopseudo hypoparathyroidism?

Answer 59

Genetic