Osteomalacia & Rickets

Question 1

def of osteomalacia

Answer 1

disorder of mineralisation of bone matrix

Question 2

def of rickets

Answer 2

disorder of defective mineralisation of cartilage in the epiphyseal growth plates of children

Question 3

aetiology

Answer 3

vitamin D deficiency
-lack of sunlight
-dietary deficiency & malabsorption
-decreased 25-hydroxylation of vitamin D (liver)
-decreased 1a-hydroxylation (kidneys)
renal phosphate wasting
-fanconis syndrome (phosphaturia, glycosuria, amino aciduria)
-renal tubular acidosis (type 2)

Question 4

epi

Answer 4

more common in females

Question 5

history of osteomalacia

Answer 5

bone pain (especially axial skeleton)
weakness
malaise

Question 6

history of rickets

Answer 6

hypotonia
growth retardation
skeletal deformities

Question 7

examination of osteomalacia

Answer 7

bone tenderness
proximal muscle weakness
waddling gait
trousseau’s sign - inflation of BP cuff above SBP for >3mins causes tetanic spasm of wrist & fingers
chvosteks sign - tapping over facial nerve causes twitching of ipsilateral facial muscles

Question 8

what is tetanic spasm

Answer 8

sudden involuntary contraction of muscles

Question 9

examination of rickets

Answer 9

pronounced frontal & parietal bones
swelling of costochondral junctions (rickety rosary)
bow legs in early childhood
knock knees in later childhood
short stature

Question 10

investigations

Answer 10

1 bloods
-low or normal ca
-low phosphate
-high alk phos
-low 25(OH) vitamin D
-high PTH in secondary hyperparathyroidism
2 radiographs
-may be normal or may show osteopenia
-looser's zones or pseudofractures in ribs or upper femur

Question 11

management

Answer 11

vit D & calcium replacement
monitor 24h urinary calcium, & serum calcium, phosphate, alk phos, PTH, vit D
treat cause (diet or sun exposure)

Question 12

where would you obtain vit D from your diet

Answer 12

fish and eggs

Question 13

what is the process for vit D synthesis from sunlight

Answer 13

sunlight converts 7-dehydrocholesterol to previtamin-D3 in the skin
this is converted in the liver to 25-hydroxyvitamin D3 by 25-hydroxylase
this is converted in the kidneys to 1,25-dihydroxyvitamin D3 by 1a-hydroxylase

Question 14

what are the functions of vit d

Answer 14

small bowel calcium absorption
bone calcium release
muscle health
bone health
BP regulation

Question 15

complications

Answer 15

bone deformities
hypocalcaemia may cause epileptic seizures
cardiac arrhythmias

Question 16

prognosis

Answer 16

improvement with vit D treatment

bone deformities in children are permanent