Vitamin D

Question 1

Below what level of vitamin D, is considered deficiency?

Answer 1

Less than 15 nmol/l

Question 2

What condition results from vitamin D deficiency in childreN?

Answer 2

Rickets

Question 3

What changes occur to the growth plate of bones with rickets?

Answer 3

The growth plate does not mineralise and it becomes thick, wide and irregular

Question 4

What condition results from vitamin D deficiency in adults?

Answer 4

Osteomalcia

Question 5

What are the symptoms of osteomalacia?

Answer 5

Can be asymptomatic
Bone pain particularly in tibia
Bone tenderness
Proximal muscle weakness without atrophy - waddlin gait

Question 6

If a patient had osteomalacia, what we be the results if imaging tests?

Answer 6

It would show osteopenia with cortical bone thinning and pseudo fractures

Question 7

An isotope bone scan can show multiple hot spots in a patient with osteomalacia. However, this could also be a sign of…?

Answer 7

Multiple metastases

Question 8

What would the biochemical test results be for a patient with osteomalacia? (Calcium, phosphate, ALP, vit D and PTH)

Answer 8

Calcium low or normal
Phosphate low or normal
ALP normal or high
Vitamin D low
PTH high

Question 9

What would the biochemical test results be for a patient with osteoporosis? (Calcium, phosphate, ALP, vit D and PTH)

Answer 9

Calcium normal
Phosphate normal
ALP normal
Vitamin D normal or low
PTH normal

Question 10

What would the biochemical test results be for a patient with hyperparathyroidism? (Calcium, phosphate, ALP, vit D and PTH)

Answer 10

Calcium high
Phosphate normal or low
ALP normal or high
Vitamin D normal or low
PTH high

Question 11

What groups of people are most susceptible to primary vitamin D deficiency?

Answer 11

Dark skinned immigrants to a less sunny country
Elderly and other housebound people
People with bizrr diets

Question 12

What are the possible secondary causes of vitamin D deficiency?

Answer 12

Partial gastrectomy
Small bowel malabsorption
Pancreatic disease
Chronic renal failure
Anticonvulsants

Question 13

What is the cause of type 1a vitamin d dependent rickets?

Answer 13

Mutation of the gene which codes for 1 alpha hydroxylase

Question 14

What is the cause of type 1b vitamin d dependent rickets?

Answer 14

25 hydroxylase deficiency

Question 15

What is the cause of type 2a vitamin d dependent rickets?

Answer 15

Defect in the vitamin d receptor gene

Question 16

What is the cause of type 2b vitamin d dependent rickets?

Answer 16

Abnormal expression of hormone response element binding proteins that interfere with the normal function of the vitamin d receptor

Question 17

Which protein is the primary controller of phosphate metabolism and reduces phosphate reabsorption in the kidneys?

Answer 17

FGF 23

Question 18

What stimulates FGF23 production?

Answer 18

PTH

Active vitamin D

Question 19

Autosomal dominant hypophosphataemic rickets is the result of a mutation in the gene for what protein?

Answer 19

FGF23

Question 20

X linked hypophosphataemic rickets is the result ima mutation in which gene?

Answer 20

PHEX gene

Question 21

What is the role of DMP1 in relation to vitamin D?

Answer 21

It is involved in osetoblast maturation and is exported to the ECm where it regulates hydroxyapetite
DMP1 inhibits FGF23 expression

Question 22

What type of rickets is dentin matrix protein 1 involved in?

Answer 22

Autosomal recessive hypophosphataemic rickets