10: Disorders of calcium metabolism

Question 1

Which chemicals increase blood calcium?

Answer 1

PTH

Vitamin D

Question 2

How do blood calcium levels increase?

Answer 2

Absorption from gut

Moves from bone to blood

Reabsorption from kidneys

Question 3

How is calcium excreted?

Answer 3

Kidneys

Question 4

Which gland regulates calcium concentration?

Answer 4

Parathyroid gland

Question 5

Which receptors on parathyroid glands sense calcium concentration?

Answer 5

Calcium sensing receptors

Question 6

How is Vitamin D obtained?

Answer 6

Diet (oily fish, red meat and eggs)

Sunlight

Question 7

What is the mnemonic for hypercalcaemia symptoms?

Answer 7

Stones (renal stones)

Bones (osteoporosis)

Groans (abdominal pain)

Psychic moans (depression)

add on polydipsia and polyuria as well

Question 8

What are the acute symptoms of hypercalcaemia?

Answer 8

Polydipsia

Polyuria

Confusion

Question 9

What is seen in chronic hypercalcaemia?

Answer 9

Myopathy

Osteoporosis > Fragility fracture

Hypertension

Abdo pain - pancreatitis, ulcers, kidney stones

Question 10

What is measured to diagnose hypercalcaemia itself?

Answer 10

Serum calcium

Question 11

What are the two most common causes of hypercalcaemia?

Answer 11

Primary hyperparathyroidism

Malignancy

Question 12

Which drugs cause hypercalcaemia?

Answer 12

Vit D - causes inc. calcium absorption, reabsorption and transfer from bones

Thiazide diuretics - increase calcium reabsorption from kidneys

Question 13

Which granulomatous diseases can cause hypercalcaemia?

Answer 13

Sarcoidosis

TB

Question 14

(High / low) bone turnover causes hypercalcaemia.

Answer 14

High bone turnover

so diseases like Paget’s

Question 15

Which tests are done to diagnose hyperparathyroidism?

Answer 15

Raised serum calcium

Raised PTH (or inappropriately normal for Ca levels)

Increased urine calcium secretion

Question 16

How does malignancy cause hypercalcaemia?

Answer 16

Bone destruction

PTHomas

Inflammatory factors activate osteoclasts

Question 17

Which liver enzyme will be elevated in hypercalcaemia secondary to malignancy?

Answer 17

ALP

Question 18

How is suspected malignancy investigated?

Answer 18

Imaging - X-ray, CT, MRI

Nuclear imaging - isotope bone scan

Question 19

How is hypercalcaemia treated?

Answer 19

Fluid resuscitation if dehydrated

LOOP diuretics (thiazides cause hypercalcaemia)

Bisphosphonates to reduce osteoclast activity

If granulomatous disease, steroids

Question 20

Which type of scan is used to view the activity of the thyroid and parathyroid together?

Answer 20

Sestamibi scan

Question 21

What is the only definitive treatment for hyperparathyroidism?

Answer 21

Surgery

i.e parathyroidectomy

Question 22

If surgery isn’t appropriate, how is hyperparathyroidism treated?

Answer 22

No treatment available

Question 23

What are some complications of hyperparathyroidism?

Answer 23

Bone disease inc. osteoporosis BONES

Peptic ulcers GROANS

Renal stones STONES

Depression PSYCHIC MOANS

Question 24

What is primary hyperparathyroidism?

Which PTH and Ca levels would you see?

Answer 24

Overactivity of parathyroids due to adenoma/carcinoma or hyperplasia

Raised PTH, raised Ca

Question 25

Which genetic syndromes are associated with primary hyperparathyroidism?

Answer 25

**MEN-1, MEN-2A** causing parathyroid tumours which secrete TSH, leading to hypercalcaemia

Question 26

What is secondary hyperparathyroidism? Which PTH and Ca levels would you see?

Answer 26

**Physiological response to low calcium levels** e.g in chronic kidney failure **Low Ca, raised PTH**

Question 27

What is tertiary hyperparathyroidism? Which PTH and Ca levels would you see?

Answer 27

**Autonomous parathyroids after years of secondary** **Ca raised, PTH raised**

Question 28

Why must you check **urinary calcium** levels as well as blood calcium when diagnosing hypercalcaemia??

Answer 28

**Hypercalcaemia w/ low urinary excretion of calcium indicates** FAMILIAL HYPOCALCIURIC HYPERCALCAEMIA, **a genetic condition**

Question 29

What is the problem in hypocalciuric hypercalcaemia?

Answer 29

**Calcium sensing receptor on parathyroid gland has higher set point for calcium** **So higher Ca conc. required before PTH is switched off**

Question 30

What are the symptoms of hypocalcaemia?

Answer 30

**Paraesthesia** **Muscle pain, tetany and weakness**

Question 31

What PTH level is seen in hypocalcaemia?

Answer 31

**High PTH level**

Question 32

What are two physical signs of hypocalcaemia?

Answer 32

**Chovstek's sign** - tapping on the parotid gland causes mouth to twitch **Trousseau's sign** - inflating BP cuff causes wrist and finger flexion

Question 33

What is an ECG sign of hypocalcaemia?

Answer 33

**Prolonged QT interval**

Question 34

What causes hypocalcaemia?

Answer 34

**Hypoparathyroidism** **Vitamin D deficiency** (causing osteomalacia/Rickets) **Chronic renal failure**

Question 35

How is **acute** hypocalcaemia treated?

Answer 35

**IV calcium**

Question 36

Which congenital syndrome causes hypoparathyroidism?

Answer 36

**DiGeorge syndrome** invariably causes absent parathyroids

Question 37

Deficiencies in which two chemicals can cause hypoparathyroidism?

Answer 37

**Vitamin D** **Magnesium** (causing hypoparathyroidism \> hypocalcaemia)

Question 38

What usually causes hypoparathyroidism?

Answer 38

**Destruction / removal of parathyroids**

Question 39

How is hypocalcaemia managed long-term?

Answer 39

**Calcium, Vitamin D supplements**

Question 40

Which ion is required to release calcium from cells?

Answer 40

**Magnesium**

Question 41

What name is given to hypocalcaemia in which PTH is **high**?

Answer 41

**Pseudohypoparathyroidism**

Question 42

What causes pseudohypoparathyroidism?

Answer 42

**Genetic mutation causing PTH resistance** rather than failure to produce PTH

Question 43

Which bone diseases are caused by Vitamin D deficiency? Which bone diseases can be caused by (amongst other things) calcium and phosphate deficiency?

Answer 43

**Rickets / Osteomalacia** ## Footnote **Osteoporosis**

Question 44

What causes Vitamin D deficiency?

Answer 44

**Lack of Vitamin D in diet** **Malabsorption** **Renal failure** **Lack of sunlight**

Question 45

**Chronic renal failure** causes a ___ \_ deficiency leading to which kind of hypoparathyroidism?

Answer 45

**Vitamin D** **secondary**

Question 46

Patients with osteomalacia / Rickets who are given Vitamin D supplements may not respond - why?

Answer 46

**X-linked hypophosphataemia**