Calcium and bone

Question 1

What is bone made up mostly of?

Answer 1

Collagen and calcium phosphate

Question 2

What adds the strength to bone?

Answer 2

Calcium phosphate

Question 3

What are the two types of bone?

Answer 3

Trabecular and cortical

Question 4

What are the characteristics of trabecular bone?

Answer 4

Porous, sponge like bone

Question 5

What are the characteristics of cortical bone?

Answer 5

Forms majority of the outside of bone - very dense material

Question 6

What is bone constantly going through?

Answer 6

A remodelling process

Question 7

What is the remodelling process a balance between?

Answer 7

Bone formation and resorption

Question 8

What cell is responsible for bone formation?

Answer 8

Osteoblasts

Question 9

What cell is responsible for bone resorption?

Answer 9

Osteoclasts

Question 10

What concentrations are important in the body to maintain strong healthy bone?

Answer 10

Calcium and phosphate

Question 11

Where is the body’s calcium found?

Answer 11

Intracellular, skeleton and extracellular

Question 12

Where is the majority of the body’s calcium found?

Answer 12

In the skeleton

Question 13

What three hormones are involved in the regulation of extracellular body calcium?

Answer 13

Calcitonin, parathyroid hormone and vitamin D

Question 14

What does parathyroid hormone do?

Answer 14

Senses calcium levels within the body

Question 15

What is calcitonin?

Answer 15

A polypeptide

Question 16

Where is calcitonin secreted from?

Answer 16

Parafollicular C cells in thyroid gland

Question 17

What activates vitamin D?

Answer 17

Enzymes within the liver and kidneys

Question 18

Besides maintaining bone strength, what else is calcium essential in?

Answer 18

Excitability of smooth and cardiac muscle, secretion of peptides and hormones in body, role in blood clotting and excitability of skeletal neuromuscular junctions

Question 19

What stimulates parathyroid hormone?

Answer 19

Hypocalcaemia

Question 20

What are the functions of parathyroid hormone?

Answer 20

Increases serum calcium, decreases serum phosphate and activates vitamin D within the kidney

Question 21

How does PTH increase serum calcium and decrease serum phosphate in bone?

Answer 21

Increase osteoclastic activity - causing increased resorption of bone - calcium released from labile pool of calcium phosphate

Question 22

How does PTH increase serum calcium and decrease serum phosphate in kidney?

Answer 22

Increases resorption of calcium and causes increased secretion of phosphate in the urine

Question 23

What needs to happen to vitamin D before it has any effect in the body?

Answer 23

Must be hydroxylated

Question 24

How does vitamin D in its active form (steroid) work in the kidney?

Answer 24

Increases absorption resulting in increase absorption of both calcium and phosphate

Question 25

What important role does activated vitamin D have in bone?

Answer 25

Maintaining mineralisation of bone

Question 26

Compare the role of calcitonin and PTH/vit D in role of serum calcium?

Answer 26

Low

Question 27

When is calcitonin secreted?

Answer 27

Extreme cases of hypercalcaemia

Question 28

What is the action of calcitonin?

Answer 28

Decreases serum calcium

Question 29

What effect does deficiency or excess of calcitonin have on bone?

Answer 29

Has no effect on bone quality

Question 30

How does calcitonin work in bone?

Answer 30

Inhibits osteoclasts - decreases bone resorption | Also moves calcium from plasma to labile pool of calcium phosphate

Question 31

What does decreased bone resorption mean with regards to calcium levels?

Answer 31

Extracellular calcium levels are lower

Question 32

How does calcitonin work in the intestines?

Answer 32

Decreases absorption - lowers levels of calcium and phosphate

Question 33

How does calcitonin work in the kidneys?

Answer 33

Decreases reabsorption of calcium and phosphate - increased excretion

Question 34

What are the clinical features of hypercalcaemia?

Answer 34

``` Patient will feel tired, confused and depressed May be history of kidney stones Arrhythmias - ECG changes Muscle weakness Constipation STONES, BONES, MOANS and ABDO GROANS ```

Question 35

What are the clinical features of hypocalcaemia?

Answer 35

Cramp and tetany of muscles Pins and needles in extremities Generally those opposite to hypercalcaemia

Question 36

What is an extreme complication of hypocalcaemia?

Answer 36

Death due to asphyxiation - unrelieved contraction of rest muscles

Question 37

What are the symptoms of hyperparathyroidism?

Answer 37

Same as hypercalcaemia | However with osteoporosis - more likely to develop bone fractures

Question 38

What is the cause of primary hyperparathyroidism?

Answer 38

Overactivity off parathyroid gland

Question 39

What are the serum levels in primary hyperparathyroidism?

Answer 39

PTH raised | Ca raised

Question 40

What is the cause of secondary hyperparathyroidism?

Answer 40

Physiological response to low calcium

Question 41

What are the serum levels in secondary hyperparathyroidism?

Answer 41

PTH raised | Ca low

Question 42

What is the cause of tertiary hyperparathyroidism?

Answer 42

Parathyroid gland becomes autonomous after many years of secondary

Question 43

What are the serum levels in tertiary hyperparathyroidism?

Answer 43

PTH raised | Ca raised

Question 44

How is primary hyperparathyroidism diagnosed?

Answer 44

Achieved from finding: - raised serum PTH - raised serum calcium - increased urine calcium excretion

Question 45

What is the management of an adenoma causing hyperparathyroidism?

Answer 45

Surgery and removal

Question 46

When is removal of can adenoma causing hyperparathyroidism encouraged?

Answer 46

When the patient is suffering from: - Renal stones - Renal impairment - Severe osteoporosis

Question 47

What is the medical management of hyperparathyroidism?

Answer 47

There is none however patients are encouraged to have a high fluid diet and high calcium and fit D diet should be avoided

Question 48

What is the most common cause of primary hyperparathyroidism?

Answer 48

Adenoma of parathyroid gland

Question 49

How does hypoparathyroidism arise?

Answer 49

Lack of cells within parathyroid gland that actively secrete PTH

Question 50

What are the causes of hypoparathyroidism?

Answer 50

Di George syndrome, malignancy, autoimmune disease

Question 51

How does Di George syndrome cause hypoparathyroidism?

Answer 51

Congenital absence of parathyroid glands

Question 52

How does malignancy cause hypoparathyroidism?

Answer 52

Destruction of cells

Question 53

How does autoimmune disease cause hypoparathyroidism?

Answer 53

Autoantibodies destroy parafollicular cells

Question 54

What are the serum levels in hypoparathyroidism?

Answer 54

Low calcium High phosphate Little or no PTH

Question 55

What are the signs and symptoms in hypoparathyroidism?

Answer 55

Same as for hypocalcaemia as well as: - Chvostek's sign - Trousseau's sign - Higher rate of fractures due to abnormalities in bone remodelling

Question 56

What is Chvostek's sign?

Answer 56

Twitching of facial muscle when gentle tapping is applied to facial nerve

Question 57

What is Trousseau's sign?

Answer 57

Inflation of BP cuff over systolic pressure for a period of time will result in tetany of muscles in hand and wrist

Question 58

How is hypoparathyroidism diagnosed?

Answer 58

Blood samples of hormone and serum electrolytes

Question 59

What is the management of hypoparathyroidism

Answer 59

Calcium and vitamin D supplements

Question 60

What is pseudohypoparathyroidism?

Answer 60

Condition caused by genetic receptor abnormality - leads to resistance of PTH

Question 61

What are the serum levels in pseudohypoparathyroidism?

Answer 61

Increased PTH decreased calcium Increased phosphate

Question 62

Why is there an increased level of PTH in pseudohypoparathyroidism?

Answer 62

Hypocalcaemia stimulates release of even more PTH

Question 63

What are the complications of pseudohypoparathyroidism?

Answer 63

Subcut calcificano, mental retardation, blunting of fourth metacarpal, obesity and bone abnormalities

Question 64

What are the causes of a lack of bit D?

Answer 64

Lack of sunlight absorption (winter, skin pigment, indoors too much) Lack of absorption of pre hormone (poor diet, coeliac) Problem with activation (Liver failure, kidney failure)

Question 65

What happens in the intestines when there is a lack of vitamin D in the body?

Answer 65

Absorption of both calcium and phosphate will be decreased

Question 66

What happens in the bone when there is a lack of vitamin D?

Answer 66

Lack of mineralisation of bone - decreased bone quality as well as increased resorption (less dense and weaker)

Question 67

What is rickets?

Answer 67

Condition in children where low vitamin D levels causes bone to become soft

Question 68

What happens when there isn't enough vitamin D in a child?

Answer 68

Legs bow as they aren't dense enough to support weight of body

Question 69

How does neonatal rickets present?

Answer 69

Soft skull and tenderness - craniotabes

Question 70

What happens at the wrists in rickets?

Answer 70

Widened epiphyses

Question 71

What is osteomalacia?

Answer 71

Similar to rickets but in adults

Question 72

How do patients present with osteomalacia?

Answer 72

Bone and muscle tenderness Pathological fractures Gait deformities (proximal myopathy)