Bone Disorders Flashcards
What is DiGeorge Syndrome? What do you see?
Disorder of pharyngeal pouch dysgenesis, see aplasia of parathyroid gland = decreased PTH secretion
What is the action of estrogen?
Increases OB activity, decreases OC activity, increases OPG secretion = decreased bone turnover
What are osteoblasts stimulated by? What are osteoclasts stimulated by? What are osteoclasts inhibited by?
OB = Estrogen, calcitriol, calcitonin, GH, TTGF OC+ = RANK-L, PTH, glucocorticoids OC- = OPG, IL-10, TGF-beta
What does anorexia nervosa cause?
hypogonadism, excessive exercise, hypopituitarism = decreased estrogen = osteoporosis
What is the action of glucocorticoids, anticonvulsants, and antidepressants?
gluco = stimulate OC anti- = decrease serum Ca2+ levels
What drugs can cause osteoporosis?
Glucocorticoids, anti-convulsants, anti-depressants
What is the most common manifestation of osteoporosis? Is this symptomatic? What does this result in physiologically?
Vertebral compression fracture, 66% asymptomatic and just presents as height loss though can be symptomatic in acute presentations. Decreases TLC
What is the DEXA score? How is it used to dx osteoporosis/osteopenia? When should a pt get it?
measures bone density, osteoporosis if <2.5 from mean density, osteopenia -1 to -2.5. Should get in all women 65+
What are lab values for osteoporosis? osteopenia?
Normal = Ca2+, PO3-, ALP, PTH
What is the 1st line therapy for osteoporosis? What are other options? What is the MOA?
Oral bisphosphonates (-onate): prevent OC activity by binding to hydroxyapatite. Calcitonin: inhibits bone resorption. Denosumab: binds RANK-L. Teriparatide: similar to endogenous PTH (give only bolus, chronic would increase OC activity), Selective Estrogen R Modulator (SERM): Raloxifene, stimulates estrogen R –> increases OPG
What are complications of spine fractures?
chronic pain dvpmt, functional disability, kyphosis and Dowager’s hump, decreased quality of life, depression
What is pseudohypoparathyroidism? What are the sxs
when PTH R (Gs-alpha subunit) does not work - short stature, short 4 & 5th digits, high PTH and low Ca2+
What is osteogenesis imperfecta? What is another name for it? What is seen w/ it? What is it often confused with?
autosomal dominant pb, also called brittle bone disease, prevent collagen type 1 synthesis (makes up bones) –> multiple bone fractures w/o hx of trauma, blue sclera, can have hearing loss (bones don’t form properly), dental imperfections (can’t synthesize dentin). Often confused w/ child abuse
What happens during osteopetrosis?
genetic defect in Carbonic Anhydrase II = abnormal osteoclast activity results in thick dense bones made of immature substance since doesn’t reshape immature new bone made by OB. Bone marrow cavities fuller, less BM
What sxs are seen w/ osteopetrosis? What does this predispose the pt to?
anemia, thrombocytopenia, neutropenia = increased extramedullary hematopoiesis + possible CN palsy due to impingement from narrower foramina caused by bone enlargement, predispose to infection
What lab values are seen with osteopetrosis? Xray findings?
normal lab values, see erlenmeyer flask bones (bone-in-bone) that flare outwards, narrow foramina caused by bone enlargement
What acquired bone disorders lead to decreased bone formation
Osteoporosis, osteopenia, osteomalacia/rickets, hyperparathyroidism
what acquired bone disorders lead to increased bone formation?
Paget’s disease, Hypertrophic osteoarthropathy
What inherited disorder leads to decrease bone formation?
osteoporosis imperfecta
What inherited bone disorder leads to increased bone density?
Osteopetrosis
In what environment do OB secrete collagen? in what environment do OC secrete collagenases?
OB = alkalosis OC = acidosis, break down bone by secreting collagenases
What is an example of a collagenase? What is it secreted by? What disorder is it deficient in?
carbonic anhydrase II, secreted by OC, deficient in osteopetrosis
What causes osteomalacia? What do pts present w/? Labs?
vitamin D deficiency –> low VD, low Ca2+ and pO3- (low absorption from gut), high PTH, high Akl Phos –> diffuse bone pain, muscle weakness, fractures, bowing of long bones
What is the tx for osteomalacia?
VD and Ca2+ supplementation –> sxs often resolve in 6 months
What is seen on xray for osteomalacia?
osteopenia (low bone density), pseudofractures (loose zones, sclerotic margins)
Who is at risk for osteomalacia?
Adults in nursing homes
Populations in northern climates w/ little sun exposure
Pts w/ chronic diarrhea or IBD (malabsorption of VD)
Lack of dietary intake of VD
Pts w/ liver or K disease, can’t convert VD to active form
Genetic conditions (organs not sensitive to VD)
Which disease are due to inherited or acquired defects in bone architecture (not due to inappropriate hormonal or bone mineral regulation)?
Osteoporosis, osteopetrosis, Paget disease
Which diseases are due to defects in bone mineral metabolism/inappropriate hormonal regulation?
osteomalacia/ricket’s, osteitis fibrosa cystica, hypervitaminosis D
What is the cause of osteitis deformans? What is another name for it?
unknown underlying cause but due to abnormal OB and OC function, overactive bone remodeling = paget’s disease
What is histology associated w/ Paget’s? Lab? Sxs? Imaging? What can it possible lead to?
Histology = thickened trabeculae w/ mosaic pattern of woven and trabecullar bone. Lab = increased Alk phos, normal Ca2+ and PO3-. CT = widened bone medullary space w/ areas of sclerosis and irregular cortex. Can lead to osteosarcoma due to disordered bone growth
What is Ricket’s? What part of bone is affected? How does this differ from osteomalacia? What is required for ricket’s to occur?
children deficient in VD, growth plate affected not bone matrix (OM). Growth plates must be open
What are the sxs associated w/ ricket’s? Labs? Xray?
reduced height and growth, bow legs (genu varum). Low VD, low Ca2+ and PO3-. X-ray = widening of epiphyseal growth plates + rachitic rosary (bead-like nodularity in anterior ribcage)
What pts do we often see ricket’s in? When is the onset?
Infants who are breastfed (infant formulas and commercial milk fortified w/ VD) AND dark-skinned (block sunlight absorption and VD production)
Early-onset 6-23 months OR later 12-15 years (child’s nutritional needs increase dramatically)
What is the tx for ricket’s? Does it resolve?
VD and Ca2+ supplements, may not resolve, extreme cases may need surgery. prognosis good if detected early
What bone condition is seen with PHPT?
Osteitis Fibrosa Cystica
What are the sxs of osteitis fibrosa cystica?
bone pain, frequent fractures, cystic bone formation filled w/ hemosiderin brown tissue + sxs of PHPT/hyperC
What is the tx for PHPT?
parathyroidectomy
What are sxs of hypocalcemia?
perioral numbness, muscle cramps, tetany, seizures
What are sxs of Paget’s disease (osteitis deformans)?
Sxs = increased hat size, bone pain, hearing loss (narrowing of auditory foramen w/ compression of CN VIII, long bone chalk-stick fractures, osteoarthritis, possible high output HF due to AV shunt formation through bone.
What is the tx for osteitis deforman?
Bisphosphonate = (-dronate), inhibits OC activity
What is hypertrophic osteoarthropathy caused by?
underlying systemic cancer (usually lung) - paraneoplastic syndrome
What are the sxs of hypertrophic osteoarthropathy?
can be asymptomatic, bony overgrowth in fingers (clubbing and nail elevation), bone pain and swelling, periostitis (inflammation periosteal layer) of long bones: synovial effusions
What is the tx for hypertrophic osteoarthropathy?
NSAIDs for pain and discomfort, tx for underlying cancer
