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Block 2 > Path > Flashcards

Path Flashcards

1
Q

appositional vs interstitial growth of cartilage

A

new cartilage formation at surface just beneath perichondrium vs lacunae chondrocytes to chondroblasts to make new internal cartilage

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2
Q

perichondrium

A

layer of dense connective tissue surrounding cartilage; has reserve chondroblasts deep to perichondrium

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3
Q

what distinguishes the types of cartilage?

A

all have ground substance consisting of chondroitin sulfate but differ by fiber type

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4
Q

hyaline vs fibro vs articular cartilage

A

most abundant and hardest cartilage d/t few collagen fibers; in articular, tracheal, costal, thyroid cartilage; matrix only visible w/ e- microscopy vs more pliable than hyaline b/c more collagen fibers –> tensile strength; in intervertebral discs, pubic symphysis, knee meniscus; matrix visible w/ light microscopy vs most pliable d/t collagen fibers + elastic fibers –> can recoil back to position –> form and flexibility; in ear (external and eustachian tube), epiglottis, larynx

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5
Q

how are lacunae connected?

A

by canaliculi –> cn give nutrients to osteocytes residing in there

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6
Q

interstitial lamellae

A

lamellae that don’t have their own Haversian system d/t remodeling –> 1st/2nd/3rd generation Haversian systems

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7
Q

osteoprogenitor cells vs blasts vs cytes vs clasts

A

undifferentiated fibroblast-like cells that give rise to blasts vs make glycoproteins and mucopolysacch to make uncalcified ground substance at external surface => osteoid vs formed when blasts = surrounded by matrix –> encased in lacunae vs large multinucleated phagocytic cells that digest bone matrix along internal surface for remodeling; found in Howship’s lacunae in compact bone

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8
Q

know what bone consists of

A

ECM: organic osteoid (type I collagen, proteoglycan, glycoprotein) –> tensile strength, inorganic hydroxyapatite (Ca2+, PO43-) –> rigidity
Cells: stem/blasts/cytes/clasts

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9
Q

bone contains internal (endosteum) and external (periosteum) lining of simple sq epithelia plus…?

A

underlying dense irreg connective tissue; and Sharpey’s fibers (attach bone to periosteum)

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10
Q

intramembranous vs endochondral ossification

A

bone formed from mesenchymal tissue w/o cartilage model –> highly vasc –> rapid cell prolif –> osteoprogenitor become blasts –> osteoid; flat bones vs bone formed from hyaline cartilage model –> cartilage cells prolif and hypertrophy –> lacunae inc in size –> calcified by lime salts –> cells below perichondrium differentiate to progenitor to blasts –> periosteal buds infiltrate enlarged lacunae => marrow space –> lime salts replaced by hydroxyapatite; happens in primary oss center in diaphysis first, then secondary oss center in epiphysis after; cartilage remains b/w dia and epiphysis => epiphyseal plate –> epiphyseal line –> longitudinal growth stops; long & short bones

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11
Q

appositional vs longitudinal growth of bone

A

inc diameter via intramembranous oss on external surface and clast activity on internal surface vs Reserve cartilage zone: resting chondrocytes ready to build bone
Zone of prolif: dividing chondrocytes in lacunae secrete bone and collagen
Zone of hypertrophy: maturing chondrocytes
Zone of cartilage calcification
Zone of provisional ossification

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12
Q

synovial joints

A

fibrous capsule w/ synovial fluid and cartilaginous articular surfaces

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13
Q

intervertebral discs: annulus fibrosis vs nucleus pulposis

A

outer fibrocartilage layer w/ collagen fibers in 90 degree planes vs gel like material from notochord –> partially displaced by fibrocartilage in adults

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14
Q

ex of dense regular connective tissue

A

tendons and ligaments

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15
Q

tendon vs ligament

A

muscle to bone; all collagen fibers run parallel; fibroblasts arranged in rows and flattened b/w thick collagen fibers; minimum vasc –> slow to heal; lubricated in tough fibrous sheet to minimize friction vs bone to bone; collagen + elastic fibers run parallel; irreg arrangement of fibroblasts

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16
Q

red/aerobic vs white/anaerobic fibers

A

small w/ rich mgb and blood supply –> slow twitch ctx and resistant to fatigue, darker ATPase, for maintenance and posture vs large w/ little mgb and blood supply –> fast twitch ctx and easily fatigued, lighter ATPase, for brief exertion of force

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17
Q

muscle spindles vs Golgi tendon

A

both = proprioceptors. senses muscle length and rate of change in muscle length –> prevent hyperelongation of muscle and tissue dmg; intrafusal muscle fibers enclosed in sheaths running parallel to extrafusal muscle fibers vs senses tendon tension and rate change of tension –> prevent excess tension in muscle and tissue dmg

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18
Q

can skel vs smooth muscle cells regenerate?

A

very limited –> replace by fibrous connective tissue scar or hypertrophy vs yes

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19
Q

Epimysium vs Perimysium vs Endomysium

A

surrounds entire muscle (ie. group of fasicles); continuous w/ tendon vs surrounds fascicle vs surrounds muscle fibers

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20
Q

skel vs cardiac vs sm muscle characteristics

A

striated, polynucleated voluntary vs striated, mono/binucleated, involuntary vs not striated, mononucleated, involuntary

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21
Q

Multi unit vs unitary smooth muscle

A

Each smooth muscle cell = innervated –> precisely controlled by ANS vs some muscle cells = innervated —> communicate via gap jxns –> synchronized ctx

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22
Q

achondroplasia vs thanatophoric dysplasia

A

both short stature and limb shortening, auto dom (homo dom = lethal). nml trunk, psychomotor nml; gain of fxn mutation in transmembrane domain of FGFR3 gene vs thoracic hypoplasia –> resp insufficiency –> lethal; gain of fxn mutation in intra/extracellular domain of FGFR3 gene

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23
Q

osteopetrosis

A

failure of clast activity –> no bone resorption –> inc bone density on XR, impaired bone re/modeling, abnlly shaped bones

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24
Q

3 types of osteopetrosis: infantile malignant vs intermediate vs adult/benign

A

most severe; Mutation in TCIRG1 gene; Inc in bone density –> weakens bone –> fx and osteomyelitis; no bone marrow development –> dec hematopoiesis –> dec leuks, RBC, PLT –> enlarged liver and spleen to compensate –> recurrent resp infxns vs Mutation in CLCN7 gene; auto rec; same pres as infant x/ moderate bone marrow vs Mutation in CLCN7 gene, auto dom; same pres as infant x/ nml bone marrow

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25
Q

imging of ostepetrosis

A

wide metaphysis –> erlenmyer flask deformity, no distinction b/w cortex and medulla

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26
Q

osteogenesis imperfecta

A

hypomineralization of skel and propensity to fx w/ minimal trauma; d/t mutation in COL1A1/2 for alpha1/2 in type I collagen; auto dom

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27
Q

type I vs II vs III vs IV collagen

A

Bone, dentin, ligament, sclera, skin vs hyaline cartilage vs Stroma of internal organs: liver, kidney, LN, blood vessels, intestines, ut vs basement membrane

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28
Q

collagen synthesis

A

Fibroblasts and osteoblasts make procollagen –> 2 α1 chains and 1 α2 chain make triple helix in Golgi –> tropocollagen –> collagen fibrils; need vit C for hydroxylation of pro/lys to make helix

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29
Q

4 types of OI: I vs II vs III vs IV

A

fx, blue sclerae for all. most common and mildest; nml stature, no bone deformity vs most severe; short vs most severe if survive neonatal; short, mod to severe bone deformity, hearing loss vs moderate; short, bone deformity, hearing loss

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30
Q

Marfan syndrome

A

multisystem d/o of connective tissue –> changes in skel, eyes, cardiovascular system; missense mutation in FBN1 gene (double neg mechanism) –> can’t make microfibrils or elastin in bone, eyes, heart/aorta

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31
Q

how to dx Marfan?

A

Ghent criteria; Major involvement of 2 of 4 organ systems (skel, eye, cardiovasc, skin) w/ minor involvement of another organ

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32
Q

Ehlers-Danlos Syndrome

A

13 heritable connective tissue d/o of joint hypermobility, skin hyperextensibility, tissue fragility; Mutation in TNXB gene, PLOD1 gene, ADAMTS2 gene

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33
Q

EDS: joint hypermobility vs skin hyperextensibility vs tissue fragility

A

can move joint beyond ROM –> luxation, sprains vs stretch skin for 4cm till feeling resistance and snaps back after release; fragile can split easily –> “cig paper scars” vs easy bruising/ecchymosis, hematoma

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34
Q

3 types of EDS: classic vs hypermobility vs vascular

A

mutation in COL5A1/2 gene –> triad of joint hypermobility, skin hyperextensibility, easy bruising; auto dom vs joint hypermobility, mild skin hyperextensibility vs mutation in COL3A1 gene –> rupture of blood vessels; auto dom

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35
Q

Paget’s

A

Inactivating mutation in SQSTM1 gene –> inc osteoclastogenesis –> inc clasts –> inc sRANKL –> bone resorption –> enlarged, deformed, densely sclerotic brittle bone; mono or polyostotic, doesn’t spread from bone to bone

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36
Q

3 phases of Pagets: Osteolytic vs mixed clast-blast vs final phase/burned out PDB

A

Predominant clast activity, 9 nuclei in giant multinucleated clasts (nmlly they have 3) vs predominant blast activity –> lamellar bone laid down unorganized –> mosaic pattern –> thick trabeculae –> encroach bone marrow cavity; clasts persist vs Bone resorption and formation slow and stop –> enlarged, deformed, densely sclerotic brittle bone

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37
Q

clinical pres of Pagets

A

asx; localized bone pain d/t bone overgrowth, fx, nerve compression, secondary osteoarthritis; skull enlargement, kyphosis, bowing

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38
Q

how to tx Pagets?

A

bisphosphonates –> dec bone resorption –> clast apop

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39
Q

labs for Pagets

A

o Inc serumALP –> bone formation
o Inc procollagen I N-terminal propeptide (PINP), serum C-telopeptide (CTx), urinary N-telopeptide (NTx), urinary hydroxyproline –> bone resorption
o Nml serum calcium and phosphate

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40
Q

Metaphyseal Fibrous Defect

A

prolif of benign fibrous tissue involving metaphysis of long bones (femur, tibia, knee) in children; Granular, red-brown area of bone w/ rubbery consistency

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41
Q

how to tx Metaphyseal Fibrous Defect?

A

curettage and bone grafting

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42
Q

fibrous dysplasia

A

mutation in GNAS1 gene –> inc cAMP –> mutated blasts –> differentiate to immature fibroblasts –> produce spicules of woven bone meshed in dysplastic fibrous tissue (looks like Chinese characters)

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43
Q

fibrous dysplasia = somatic mosaic dz, meaning?

A

Mutation occurs after fert in somatic cells –> all cells derived from mutated cells have dysplastic features

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44
Q

imging of fibrous dysplasia

A

Radiolucent lesion w/ “ground glass” pattern

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45
Q

Syndromic forms of fibrous dysplasia: Mazabraud Syndrome vs McCune-Albright Syndrome

A

benign d/o of soft tissue myxomas w/ fibrous dysplasia vs Post-zygotic, sporadic, somatic mutation of GNAS1 gene –> inc Gs –> polyostotic fibrous dysplasia, melanin prod/cafe au lait spots, estrogen prod/precocious puberty

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46
Q

osteoporosis

A

metabolic bone dz w/ low bone mass, microarchitectural disruption and skeletal fragility –> dec bone strength and inc risk of fx

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47
Q

primary osteoporosis: type I vs type II

A

Cancellous > cortical bone loss at menopause b/c no estrogen; Estrogen promotes antipop blast and proapop clast vs Cortical bone loss b/c dec bone stem cell precursor –> dec blast –> dec bone formation

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48
Q

secondary osteoporosis: hypogonadism vs hyperthyroid vs Immobilization/Disuse osteoporosis vs meds

A

No testosterone, estrogen, or androgen receptors in blasts –> accelerated bone loss vs Excess thyroid hormone –> accelerated bone resorption vs eh vs long term corticosteroids, anticoag like heparin (inc resorption, dec formation), anticonvulsant

49
Q

juvenile idiopathic osteoporosis

A

Primary bone demineralization b/c low bone formation

50
Q

clinical pres of osteoporosis

A

o Back pain, chronic dull back ache
o Loss of height, kyphosis; unsure of gait

51
Q

labs of osteoporosis

A

Ca2+, PO43-, and ALP nml in primary osteoporosis; Likely not nml in secondary osteoporosis

52
Q

imging for osteoporosis

A

verticalization (Non-weight bearing/horizontal trabeculae = resorbed first –> prominent weight bearing/vertical trabeculae), pic frame (Trabecular bone = radiolucent –> vertebrae has “picture frame” appearance), cortical thinning

53
Q

osteonecrosis

A

bone death d/t compromised blood flow in bone and bone marrow; multifactorial

54
Q

traumatic vs nontraumatic osteonecrosis

A

fx –> disruption of arteries vs glucocorticoids, immunosuppressants, alc

55
Q

clinical pres for osteonecrosis

A

o Pain in groin, thigh, buttock, walking
o Reduced ROM in hip joint
o Crepitus

56
Q

imging for osteonecrosis

A

CT or MRI showing avasc necrosis

57
Q

osteoarthritis/DJD

A

genetic chronic dz of synovial joints from breakdown of articular cartilage –> lose hyaline cartilage; most common form of arthritis

58
Q

risk factors of osteoarthritis

A

o inc w/ age, more in women and athletes, obesity
o radiologic OA > symptomatic OA
o osteoporosis, previous joint injuries

59
Q

3 stages of OA

A

o Stage 1: absolute or relative overload of cartilage matrix –> IL-1 and TNFα communicate in auto/paracrine fashion in cartilage –> activate matrix-degrading enzymes
o Stage 2: fibrillation and erosion of cartilage –> release proteoglycan and collagen into synovial fluid
o Stage 3: breakdown products of cartilage activate inflamm response in synovial membrane –> irreversible loss of cartilage –> compensatory bone overgrowth to stabilize joint

60
Q

what is nml cartilage like? superficial vs middle vs deep zone vs tidemark vs Calcified cartilage ?

A

Articular surfaces at synovial joints = lined by hyaline cartilage (type II collagen + water). collagen and flat chondrocytes parallel to surface vs collagen and chondrocytes in random orientation vs collagen and chondrocytes perpendicular to surface vs boundary layer b/w uncalcified and calcified cartilage vs chondrocytes and calcium apatite crystals; intermediate b/w cartilage and bone

61
Q

clinical pres of OA

A

o Pain, morning stiffness, reduced ROM, joint effusions, gross joint deformities
o Crepitus
o Tenderness to palpation
o Osteophytes
o Muscle atrophy

62
Q

types of OA: primary vs secondary

A

 Age, women
 Localized
 Bouchard nodes at PIP, Heberden nodes at DIP vs Genetic, obesity
 Monoarticular or polyarticular

63
Q

labs for OA

A

o ESR, blood count, UA nml
o Synovial fluid nml (If inflamed: cloudy, translucent, less viscous w/ high leuks)

64
Q

imging for OA

A

o Intraarticular loose bodies (free bone or cartilage frag in synovial fluid)
o Joint space narrowing, change in contouring of joint
o Subchondral sclerosis, subchondral cyst
o Osteophytes

65
Q

neuropathic arthropathy

A

progressive joint destruction d/t disturbance in joint innervation; Caused by DM (tarsal bones), syphilis (hip, knee), syringomyelia (shoulder, elbow)

66
Q

clinical pres for neuropathic arthropathy

A

o No pain
o Swollen, warm, erythematous joint; joint instability or dislocation

67
Q

imging for neuropathic arthropathy

A

o Pencil-cup deformity (Bone resorption, Destruction of articular surface, Subchondral sclerosis)

68
Q

gout

A

Endogenous (from D/RNA) purine degradation → deaminated to hypoxanthine and xanthine → xanthine oxidase converts to uric acid → overprod (10% of gout) or underexcretion (90% of gout) of uric acid → high serum and urine uric acid conc => hyperuricemia and hyperuricosuria → MSU crystals in joints

69
Q

which organs elim uric acid?

A

o Kidney elim 2/3, GI tract elim 1/3 of uric acid

70
Q

primary uricemia = caused by?

A

HPRT defic
* Caused by X-linked mutation in HPRT1 gene encoding HPRT that converts purines back into nucleotides in salvage pathway
o Mutation –> excess purines –> uric acid –> MSU

71
Q

primary uricemia: Lesch-Myhan syndrome vs Kelley-Seegmiller syndrome vs Phosphoribosyl pyrophosphate synthetase superactivity

A

overprod of uric acid, o Psychomotor delay, cognitive disturbances, self-injuring behavior vs gouty arthritis vs o Gain of fxn mutation in PRSP gene encoding PRS enzyme that makes phosphoribosyl pyrophosphate; Mutation –> excess purines –> uric acid –> MSU; early onset severe form = gout, urolithiasis, neurodevelopmental anomalies, or late onset mild form = gouty arthritis

72
Q

risk factors of gout

A

age, men, immunosuppressants and alc inc uric acid, obesity, purine rich foods (red, organ meats)

73
Q

4 stages of gout

A

Stage 1: Asx hyperuricemia
Stage 2: monoarticular acute gouty arthritis; Can be resolved spont after days to weeks; Inflamm response: MSU crystals = phag by macs and synovial lining cells –> activate inflammasome in synovial macs –> activate caspase-1 –> IL-1β –> neu influx into synovium –> resp burst and cytokine release –> Use IL-1β antagonists to tx gout flares
Stage 3: Intercritical gout; Asx b/w attacks of gouty arthritis but ongoing deposition of uric acid crystals
Stage 4: Chronic tophaceous gout; Polyarticular gouty arthritis and tophi (deposit of MSU crystals w/ longstanding hyperuricemia; painless)

74
Q

labs for gout

A

joint aspiration –> neutrophilic leukocytosis, high ESR (nonspecific), intracellular MSU in synovial fluid via polarized light microscopy; needle shaped, strongly negative birefringent crystals

75
Q

imging for gout

A

“punched out” extraarticular erosions w/ overhanging edge

76
Q

Calcium pyrophosphate dihydrate deposition dz

A

metabolic joint dz from deposition of CPPD crystals in joints, esp articular hyaline and fibrocartilage

77
Q

familial vs secondary CPPD

A

Gain of fxn mutation in ANKH gene encoding transmembrane protein transporting PPi out of cells to ECM; Mutation –> more PPi in ECM –> CPPD crystals in joints; Auto dom vs From hypophosphatasia, hypomagnesemia, hyper/hypoparathyroidism, hemochromatosis

78
Q

inflamm response of CPPD

A

CPP crystals = phag by synovial macs –> activate inflammasome –> activate caspase-1 –> IL-1β –> neu influx into synovium –> resp burst and cytokine release

79
Q

clinical pres of CPPD

A

Asx; Similar to osteoarthritis, acute gouty arthritis, RA, neuropathic arthropathy

80
Q

labs for CPPD

A

Synovial fluid analysis shows CPPD crystals –> Rhomboid-shaped, weakly positively birefringent crystals; harder to detect than MSU crystals b/c polymorphic

81
Q

imging for CPPD

A

o Radiopaque
o Deposited in hyaline or fibrocartilage
o Thin, dense, linear calcifications parallel to articular surface separate from underlying subchondral bone

82
Q

Basic calcium phosphate deposition dz

A

basic calcium phosphate crystals in periarticular soft tissue

83
Q

Basic calcium phosphate deposition dz: Acute calcific periarthritis vs Milwaukee shoulder syndrome

A

Asx;
o Severe shoulder pain, swelling, warmth, erythema
o Women 30-50yo
vs
o Rapidly progressive and destructive shoulder arthritis
o Severe shoulder pain, swelling, limited ROM
o Women >70yo

84
Q

toxic myopathies: Statin-induced vs Glucocorticoid-induced vs Chloroquine-induced vs alc-induced

A

muscle pain, muscle weakness, rhabdomyolysis, inc serum kinase –> muscle bx shows necrosis, phag, regeneration vs muscle protein catab in type II fibers –> muscle bx shows atrophy of type II fibers vs Inhibit lysosomal fxn and autophagy in type I fibers –> autophagic vacuoles on light microscopy –> muscle weakness vs o Alc and acetaldehyde = inhibitors of muscle protein synthesis –> acute (muscle weakness, necrosis, inc serum creatine kinase and mgb) or chronic (atrophy of type II fibers)

85
Q

Dystrophinopathies

A

X linked rec d/o caused by mutation in DMD gene on Xp21 encoding dystrophin; no dystrophin –> Ca2+ flows in b/c inflamm mediators of dystrophic muscle inc nitric oxide synthase –> destabilize ryanodine receptors of SR –> excess Ca2+ enters –> muscle fiber necrosis –> replaced by adipose and fibrotic connective tissue –> muscle weakness

86
Q

clinical pres of Dystrophinopathies

A

Weakness in proximal and LE first then spreads up and out

87
Q

Becker muscular dystrophy vs Duchenne muscular dystrophy

A

mild; Dystrophin lvls = 30-80% of nml
Wheelchair by 16yo
Hypercontracted fibers (intensely stained red H&E fibers)
Dystrophin immunochemistry confirms irreg, reduced, discontinuous dystrophin
Moderate inc in serum CK
vs severe; Dystrophin lvls = 5% of nml
Mild cognitive impairment, delay in development of gross motor skills –> wheelchair by 12yo
Hypercontracted fibers (intensely stained red H&E fibers)
Dystrophin immunochemistry confirms complete absence of dystrophin
Severe inc in serum CK
Incomplete muscle repair –> muscle fiber necrosis/myonecrosis –> fibrosis from collagen fibers and adipose –> stiffness and contractures –> weakness
Dilated cardiomyopathy, conduction abnormalities, resp insufficiency –> all lead to death

88
Q

myotonic dystrophy: DM1 vs DM2

A

Gain of fxn mRNA mutation where hundreds to thousands of CTG trinucleotide rpt in DMPK gene –> DMPK mRNA transcript binds and sequesters musclebind-like splicing regulator 1 (MBL1) –> disrupts nml splicing –> abnl splicing of transcript for chloride channel CLC1 –> CLC1 can’t perform nml muscle ctx –> myotonia vs o Gain of fxn mRNA mutation where hundreds to thousands of CCTG tetranucleotide rpt in ZNF9 gene encoding RNA-binding protein

89
Q

Emery-Dreifuss muscular dystrophy

A

X-linked mutation in EMD gene encoding emerin, X-linked mutation in FHL1 gene encoding 4.5 LIM domains-1 protein, auto dom > rec mutation in LMNA gene encoding lamin A & C –> Triad of joint contractures, progressive muscle weakness and wasting from humero-peroneal distribution to scapular and pelvic girdle muscles, dilated cardiomyopathy

90
Q

Fascioscapulohumeral muscular dystrophy

A

Gain of fxn mutation of DUX4 gene –> reduction of satellite rpt array –> disrupts methylation –> chromatin relaxation –> inc DUX4 transcpxn; Progressive muscle weakness of face –> shoulder –> arms –> abd, foot

91
Q

Limb-girdle muscular dystrophy

A

auto rec > dom mutation in CAPN3 gene encoding calpain-3 for regulating sarcomere formation and remodeling –> Shoulder and pelvic girdle atrophy

92
Q

Congenital Myopathies: central core dz vs nemaline atrophy vs centronuclear myopathy vs Congenital fiber type disproportion

A

auto dom Mutation in RYR1 gene –> cores in muscle cells = present but oxidative activity absent vs auto rec Mutation in NEB gene encoding nebulin –> small rod-like inclusions in muscle fibers vs X-linked Mutation in myotubularin (MTM1) gene –> abnlly large, vesicular, central nuclei vs o auto dom or rec mutation in TPM3 gene –> smaller type I fibers than type II

93
Q

Ion channel myopathies: Hyperkalemic periodic paralysis (hyperPP) vs Hypokalemia periodic paralysis (hypoPP)

A

Mutation in SCN4A gene encoding for sodium channel –> depolarization vs Mutation in CACNA1S gene for calcium channel –> excitation-initiation ctx; low potassium = trigger

94
Q

osteomalacia

A

dec mineralization of newly formed osteoid in adults d/t vit D deficiency

95
Q

where to get D2 vs D3?

A
  • D2 = ergocalciferol, in food
  • UV –> 7-hydrocholesterol –> D3 = cholecalciferol
96
Q

how are D2/3 hydroxylated?

A

Hydroxylation of D2/3 via 25-hydroxylase in hepatocytes –> 25-hydroxycholecacliferol = calcidiol –> hydroxylation via 1α-hydroxylase –> active form of vit D = 1,25-(OH)2D = calcitriol

97
Q

how are D2/3 inactivated?

A

24-hydroxylase (CYP4A1) –> 24,25-dihydrocholecalicferol = calcitroic acid

98
Q

Low Ca2+ levels vs High Ca2+ levels

A

PTH inc –> calcitriol –> clast resorption –> Ca2+ and PO43- released in blood
 intestinal absorption of Ca2+ and PO43-
 Ca2+ and PO43- reabsorption in proximal tubules
 stimulate blasts to make calcium-binding protein osteocalcin for bone development
vs
o PTH dec  no calcitriol
o Thyroid secretes calcitonin  inhibit clast activity and excrete Ca2+ and PO43-

99
Q

3 stages of osteomalacia

A

o Stage I: calcidiol dec –> dec resorption and inc Ca2+ absorption –> hypocalcemia
o Stage II: hypocalcemia –> inc PTH (secondary hyperparathyroidism) –> inc clast activity; Inc plasma ALP; Dec plasma phosphate
o Stage III: secondary hyperparathyroidism can’t keep up –> hypocalcemia and hypophosphatemia

100
Q

clinical pres of osteomalacia

A

o Asx
o Diffuse bone pain, proximal muscle weakness/myopathy –> difficulty walking and getting up
o Bone fx w/ little trauma
o Bowing deformity of long bones in LE
o Neuromuscular irritability

101
Q

labs for osteomalacia and rickets

A

o Dec calcidiol, phosphate
o Inc PTH, calcitriol, ALP
o Low Ca2+ in stage I, nml in stage II, low in stage III

102
Q

img for osteomalacia

A

o Large and biconvex vertebral discs
o Looser zones representing incomplete fx
o Coxa profunda hip deformity: Hip socket = too deep –> severe pain

103
Q

how to dx osteomalacia?

A

o Bone bx
 Give 2 courses of tetracycline 10d apart prior to full thickness undecalcified bone bx
 Tetracycline analysis w/ fluorescent microscopy
o Nml: separate fluorescent bands = 1 um for qd b/w courses of tetracycline
o Osteomalacia: no fluorescent line, or maybe single or double bands

104
Q

rickets

A

dec mineralization of cartilage in epiphyseal growth plates in children d/t vit D or phosphate deficiency

105
Q

how do kids get vit D vs phosphate defic?

A

o From prolonged breastfeeding + no sun exposure or vit D supplementation vs
o Renal phosphate wasting
o Hereditary

106
Q

clinical pres of rickets

A

skull deformities (craniotabes, frontal bossing, delayed suture fusion of anterior fontanelles), dental deformities, limb deformities (genu valgus/varus), chest deformities, muscle weakness

107
Q

imging for rickets

A

o Widening and disorganization of epiphyseal growth plate w/ cupping and fraying
o Long bone shafts = osteopenic
o Thin cortices
o Looser zones, greenstick fx

108
Q

Osteitis fibrosa cystica

A

metabolic bone dz d/t hyperparathyroidism (autonomous overprod of PTH)

109
Q

what happens if you inc PTH?

A

o Inc clast activity –> bone resorption –> inc serum Ca2+ –> inc renal tubular reabsorption of Ca2+ and dec reabsorption of PO43-
o Inc gastrointestinal Ca2+ absorption
o Inc 1α-hydroxylase –> inc calcidiol to calcitriol
o Stimulates both blasts and clasts –> bone formation and resorption

110
Q

labs for OFC

A

o Inc PTH, serum Ca2+, 24hr urinary Ca2+, calcitriol, ALP
o Dec serum PO43-, calcidiol

111
Q

imging for OFC

A

o Demineralization/diffuse osteopenia
o Thin cortices especially prox and middle phalanges of 2nd and 3rd fingers
o Salt and pepper sign
o Brown tumors w/ lytic lesions

112
Q

Renal Osteodystrophy

A

metabolic bone dz d/t renal failure or end-stage renal dz; * Chronic renal dz –> dmged kidneys –> dec 1α-hydroxylase –> no calcidiol to calcitriol –> calcitriol defic –> dec intestinal absorption of Ca2+ –> hypocalcemia –> inc PTH –> secondary hyperparathyroidism

113
Q

5 skel changes for ROD

A

o Inc clast bone resorption like osteitis fibrosa cystica
o Delayed mtrix mineralization like osteomalacia
o Bowing and softening of bones
o Inc bone mass like osteosclerosis
o Dec BMD via DEXA

114
Q

clinical pres for ROD

A

o Adults show osteitis fibrosa cystica and osteomalacia
o Children show rickets and growth retardation
o Basilar invagination

115
Q

labs for ROD

A

o Inc phosphate, PTH, ALP
o Dec calcium, calcidiol (can be nml), calcitriol

116
Q

imging for ROD

A

o Alternating bands of opaque sclerotic bone and nml dense bone => rugger jersey spine

117
Q

imging for Pagets

A

bone scintigraphy w/ technetium (pos when inc uptake of radionuclide)

118
Q

imging for MFD

A

metaphysis protruding into medullary cavity

119
Q

Marfan’s microfibrils in bones: in general vs Dolichocephaly vs Dolichostenomelia vs Arachnodactyly

A

Excessive linear growth of long bones and joint laxity –> taller vs long narrow skull vs disproportionately long limbs vs abnlly long and slender fingers

Block 2 (16 decks)

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