MISC BONE DISORDERS- OSTEOMALACIA

Question 1

osteomalacia
- define
- children

Answer 1

softening of bones due to vit d, calcium, phosphorus deficiency resulting in faulty mineralization
- in children–> rickets (in growth plates)

Question 2

osteomalacia normal physio
- how are calcium and phosphorus regulated

Answer 2

osteoblasts secerte collagen to create framework then hardened with deposits of calcium and PO4 to form healthy strong bone

• Calcium and PO4 levels regualted by vit D

Question 3

what does vit D need to be effective

Answer 3

• adequate vit D levels (ingest/sunlight)
• conversion into active form (in liver and then kidneys
• calcitriol inc calcium absorp at kidney and intestine

Question 4

low blood calcium effects

Answer 4

• increases PTH secretion
• stim reabsorp of calcium and some phosphorus from bone into blood stream
• inc active vit D

Question 5

osteomalacia patho
- children v. adults

Answer 5

w out adequate Ca, vit D, PO4—> mineralization deos not occur

• in adults growth plates closed— inc risk fracture w/ diffuse bone/joint pain + difficult walking
• in children growth plates open — bone softening, impair growth, malformation

Question 6

osteomalacia causes

Answer 6

vit D deficiency MCC
- intestinal malabsorp (crohns, celiac)
- breastfeed child
- dec UV light exposure
- phenytoin
- liver + kidney ds

insuff Calcium intake
longstanding INC of PTH (hyperparathyroid)–> causes PO4 low, PTH will take Ca out of bone

Question 7

osteomalacia presentation

Answer 7

• bone pain, tenderness, musc weakness (lower spine, pelvis, LE)
• inc fracture
• difficult walking, waddling gait
• S/sx low calcium (musc spasm, troussea/chvosteks, tingling/numb)

Question 8

rickets specific sx

Answer 8

• softening of skull bones (craniotabes)
• genu varum (leg bowing)
• rachitic rosary (bumps on front chest)
• delayed closure fontanelles
• prominent frontal bones

Question 9

osteomalacia dx suspicion

Answer 9

suspect in case of bone pain assoc with GI malabsoprtions, chronic hep ds, or CKD

Question 10

osteomalacia dx
- labs
- xray
- rickets dx?

Answer 10

labs
- dec vit D, dec Ca, inc alk phos

xray
- +/- osteopenia
- looser zones- pseudo fractures (mc in inf/sup pubic rami)

rickets
- epiphysial/metaphyseal abnorm of bone (flaring, cupping, fraying)
- leg bowing

Question 11

osteomalacia tx

Answer 11

• tx underlying cause
• oral vit D supplement
• if pt w/intestinal malabsorp or poor PO intakes —-> PO calcium