Vitamin D Flashcards
Below what level of vitamin D, is considered deficiency?
Less than 15 nmol/l
What condition results from vitamin D deficiency in childreN?
Rickets
What changes occur to the growth plate of bones with rickets?
The growth plate does not mineralise and it becomes thick, wide and irregular
What condition results from vitamin D deficiency in adults?
Osteomalcia
What are the symptoms of osteomalacia?
Can be asymptomatic
Bone pain particularly in tibia
Bone tenderness
Proximal muscle weakness without atrophy - waddlin gait
If a patient had osteomalacia, what we be the results if imaging tests?
It would show osteopenia with cortical bone thinning and pseudo fractures
An isotope bone scan can show multiple hot spots in a patient with osteomalacia. However, this could also be a sign of…?
Multiple metastases
What would the biochemical test results be for a patient with osteomalacia? (Calcium, phosphate, ALP, vit D and PTH)
Calcium low or normal Phosphate low or normal ALP normal or high Vitamin D low PTH high
What would the biochemical test results be for a patient with osteoporosis? (Calcium, phosphate, ALP, vit D and PTH)
Calcium normal Phosphate normal ALP normal Vitamin D normal or low PTH normal
What would the biochemical test results be for a patient with hyperparathyroidism? (Calcium, phosphate, ALP, vit D and PTH)
Calcium high Phosphate normal or low ALP normal or high Vitamin D normal or low PTH high
What groups of people are most susceptible to primary vitamin D deficiency?
Dark skinned immigrants to a less sunny country
Elderly and other housebound people
People with bizrr diets
What are the possible secondary causes of vitamin D deficiency?
Partial gastrectomy Small bowel malabsorption Pancreatic disease Chronic renal failure Anticonvulsants
What is the cause of type 1a vitamin d dependent rickets?
Mutation of the gene which codes for 1 alpha hydroxylase
What is the cause of type 1b vitamin d dependent rickets?
25 hydroxylase deficiency
What is the cause of type 2a vitamin d dependent rickets?
Defect in the vitamin d receptor gene
What is the cause of type 2b vitamin d dependent rickets?
Abnormal expression of hormone response element binding proteins that interfere with the normal function of the vitamin d receptor
Which protein is the primary controller of phosphate metabolism and reduces phosphate reabsorption in the kidneys?
FGF 23
What stimulates FGF23 production?
PTH
Active vitamin D
Autosomal dominant hypophosphataemic rickets is the result of a mutation in the gene for what protein?
FGF23
X linked hypophosphataemic rickets is the result ima mutation in which gene?
PHEX gene
What is the role of DMP1 in relation to vitamin D?
It is involved in osetoblast maturation and is exported to the ECm where it regulates hydroxyapetite
DMP1 inhibits FGF23 expression
What type of rickets is dentin matrix protein 1 involved in?
Autosomal recessive hypophosphataemic rickets
