MS UWorld 3 Flashcards
Effects of PTH on calcium and phosphate
Increases serum calcium by activating osteoclasts (via blasts, RANK) and increasing kidney absorption
Increases URINE phosphate by decreasing kidney absorption
Achondroplasia: mutation and inheritance
Autosomal dominant activating mutation of FGF-R3
Drug-induced lupus: what causes it, and how are these things metabolized
Drugs are acetylated in liver
Examples include hydralazine, procainamide, isoniazide
Artery at risk in femoral neck fracture
Medial circumflex
Drugs that can lower risk of breast cancer and bone fractures
Selective estrogen receptor modulators (SERMs) are agonists at bone (limit osteoporosis) and antagonists at mammary tissue
Clomiphene, tamoxifen, raloxifene
Tibeal nerve injury presentation
Inability to curl toes, loss of sensation on plantar foot. Foot is everted and dorsiflexed (can’t invert or plantarflex)
Bone density in black and white women
Higher in black women
Risk factors for osteoporosis
Smoking, menopause, corticosteroids, inactivity, white, low body weight, EtOH
In allergy, what cytokine is responsible for antibody class shift?
IL-4, secreted by Th2 cells after initial exposure, cause isotype switching to IgE
IL-5 stimulates IgA production
Alkaptonuria
Benign childhood deficiency of homogenistic acid oxidase, important in phenylalanine and tyrosine metabolism. Accumulation of homogenistic acid causes pigmentation prolems, and deposits also cause arthritis later in adulthood.
Trabecular thinning with fewer interconnections
osteoporosis
Osteoid matrix accumulation around trebeculae
Vitamin C deficiency
Subperiostial resorption with cystic degeneration
Hyperparathyroidism
Lamellar bone structure resembling a mosaic
Paget’s disease of bone
Avascular necrosis associated with
Sickle cell disease, SLE, steroids, EtOH
Osteomyelitis in sickle cell
salmonella
Bacillus anthracis capsule, appearance on culture
Contains D-Glutamate instead of polysaccharide
Forms non-hemolyzing adherent colonies, described as serpentine or medusa head.
Associate this with working with animals (especially goats), not in the USA.
Bisphosphonates
structural analogues of pyrophosphate, end in -dronate (alendronate, risedronate, ibandronate)
Make hydroxyapatite more insoluble and interfere with osteoclasts to decrease bone resorption
Used to treat Pagets, osteoporosis, malignancy-induced hypercalcemia.
Acute dystonia due to antipsychotic use
due to blockage of D2 receptors
sudden onset pain and stiffness
An extrapyramidal symptom, Happens abruptly between 4 hours and 4 days
Adverse effects of succinylcholine
Malignant hyperthermia in genetically susceptible patients or with halothane
Sever hyperkalemia in pts with burns, myopathies, crush injuries, denervation
Bradycardia from parasympathetic stimulation or tachycardia from symathetic ganglionic effects
How does succinylcholine work
Depolarizing neuromuscular blocking agent. Binds to nicotinic ACh receptor but is not degraded by AChE –> continuous stimulation and inactivation of end plate.
Phase I = flaccid paralysis, phase II = desensitization non-depolarizing blockade
Most common rotator cuff injury
Supraspinatus tendon, which is an abductor
Pseudogout crystals
Calcium pyrophosphate, rhomboid crystals with weakly positive birefringence
Note: knee is more often in pseudogout, Metatarsophalangeal more common in gout
Pityriasis versicolor (tinea versicolor)
Benign skin condition of hyper or hypo pigmented skin patches or papules. Caused by malassezia furfur. Common in areas with hot or humid climates
Serum sicknes
Type III HSR, produces fever, urticaria, arthralgias, glomerulonephritis, lymhadenopathy 5-10 days after exposure to antigen. Circulating immune complexes can develop and deposit, activate neutrophil infiltration, fibrinoid necrosis, and complement activation (low serum complement).
common rxn to sulfa drugs
Blue sclera and history of multiple fractures suggest
osteogenesis imperfecta - deficiency/abnormality in type I collagen –> impaired bone matrix formation
Osteoblast activity reflected by what lab value?
Alk phos
Which part of vitamin D metabolism uses sunlight?
First reaction: 7-dehydrocholesterol (provitamin D3) to cholecalciferol
Ulnar nerve injury
From a fracture or medial epicondyle of humerous or fracture hook of hamate
Loss of sensation of 5th and middle of 4th fingers, palmar and dorsal hand. Flattened hypothenar eminance. Ulnar claw on digit extension.
Antibodies in RA
anti-cyclic citrullinated peptide (anti-CCP)
Skeletal muscle contraction: Calcium binds to:
Troponin C on thin filaments, which shifts tropomyosin to expose myosin binding sites on actin filament
Rash and muscle weakness
dermatomyositis
What does the rash in dermatomyositis look like?
Grotton papules: red flat-topped papules with a light scale that appear over bony prominences such as MCP, PIP, DIP
Heliotrope rash: erythematous or violaceous eruption on upper eyelids and periorbital skin
Winged scapula shoulder injury: cannot abduct arm past horizontal, when pt presses anteriorly on wall the scapula isn’t anchored to thoracic cage
Injury of serratus anterior, due to lesion of the long thoracic nerve. Occurs in axillary node dissection after mastectomy
What drug promotes osteoporosis?
Chronic corticosteroids, like prednisone.
Side effects of prednisone
Cushing like symptoms (weight gain, central obesity, muscle breakdown), cataracts, acne, osteoporosis, htn, peptic ulcers, hyperglycemia, psychosis
Septic arthritis findings and treatment
High synovial WBCs, no crystals. With no other info, assume it is gonococcus and treat with ceftriaxone
Marfan’s is a defect in
fibrillin, which is a component of microfibrils that form sheath around elastin fibers
Bacteria associated with wool
bacillus anthracis
What toxins are associated with b. anthracis?
The anthrax exotoxin has several components
- Edema factor acts as adenylate cyclase, causing edema and phagocyte dysfunction
- Lethal factor is a protease, inhibits MAPK signaling, causes apoptosis and multisystem physiologic disruption
Homeless alcoholic M with recurrent nosebleeds, swollen gums, ecchymoses, hyperkeratosis, poor healing
Malnutrition –> scurvy, vitamin C deficiency
Symptoms of vitamin C deficiency
Collagen synthesis defect. VC is necessary for hydroxylation of proline and lysine in collagen synthesis. Capillary walls are fragile, prone to bruising and bleeding. Swollen gums, poor wound healing, “corkscrew” hair. Bony deformities, subperiosteal hemorrhages. Weakened immune response.
Radial head subluxation
Most common elbow injury in kids. Happens from sudden traction on outstretched and pronated arm. Torn annular ligament, which is what hold the radius to the ulna. Child is not in pain if not moving. Holds arm close to body, pronated and extended.
Fall on outstretched hand, persistent wrist pain and snuff box tenderness: dx and complication
Scaphoid fracture. The dorsal carpal branch of the radial artery goes over the scaphoid, and fracture can cause avascular necrosis.
Pain and numbness in dorsum of foot, cannot dorsiflex ankle. What nerve is injured and how did it happen?
Injury to the common peroneal nerve. Trauma or compression of lateral leg, or fibular neck fracture.
Fever, flank pain, difficulty walking, inguinal mass. Pain when hip is extended.
Potentially a psoas abscess. Risk factors are DM, IVDU, HIV, immunosuppression.
Nerve that passes through Obturator foramen
Obturator nerve. Supplies medial compartment of thigh. Injured during pelvic surgery and causes decreased adduction
Nerve associated with foot drop
Common peroneal
Most commonly dislocated joint in the body
Glenohumeral joint, aka shoulder. Most common is anterior dislocation, from forceful external rotation and abduction of arm at shoulder. Injures axillary nerve. Deltoid is flattened, protrusion of acromium, loss of sensation over deltoid and lateral arm, loss of arm abduction, sense of axillary fullness.
Dactylitis (sickle cell hand foot disease)
Painful swelling of hands and feet. Common presentation of sickle cell in young kids, due to decreased haptoglobin (which has bound to free hemoglobin from hemolysis)
Winged scapula: nerve, muscle, cause
Long thoracic, serratus anterior, axillary node dissection (mastectomy) or stab wound
Prepatellar bursitis
Due to prolonged kneeling. Common in roofers, carpenters, plumbers. Knee pain, erythema, swelling, inability to kneel
Most common rotator cuff injury
Supraspinatus muscle (suprascapular nerve)
Test for supraspinatus pathology
“Empty can test”, Abduct arms to 90 degrees, then flex 30 degrees with thumbs pointing to floor. Doctor pushes down on arms
Bones of hand likely to be injured on fall on outstretched hand
Lunar and schapoid
Injury grabbing a tree branch on a fall, or infant getting upward force on arm in delivery
Klumpke palsy, tear of lower trunk (C8-T1). Causes claw hand
