Mehl. MSK Peds rickets, connective tissue 04-08 (1) Flashcards
Yra 2 brachial injuries.
Erb-Duchenne (C5-C6)
Klumpke (C8-T1)
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Rickets definition?
vitamin D deficiency in children.
Osteomalacia definition?
vitamin D deficiency in adults.
craniotabes (soft skull), rachitic rosary (bony knobs at costochondral junctions), genu varum (bowing of tibias). Dx?
Rickets
Activated vitamin D (1,25) is necessary to convert ??
to convert unmineralized osteoid into mineralized hydroxyapatite, therefore hardening bones.
In both rickets and osteomalacia, patient will have increased what?
“increased unmineralized osteoid,” or “deficient mineralization of osteoid.”
Important cause of Vit D deficiency on USMLE is impaired ???
Impaired intestinal malabsorption (i.e., CF, Crohn).
For CF, answer can be written as “exocrine pancreas insufficiency.”
x-ray is buzzy finding in osteomalacia/rickets.?????
“Pseudofracture”
“Pseudofracture” buzzy for what?
osteomalacia/rickets
Rickets arrows? Ca, PO4, PTH?
Decr. Ca
Decr. PO4
incr. PTH (due to ̄ negative feedback at parathyroid glands)
Osteopetrosis. Osteoclast dysfunction resulting in recurrent fractures in children due to bone density being too high. Sounds weird, but bone strength is based on balanced internal architecture of canals and networks, not just density alone.
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Osteopetrosis. HY DDx?????
HY DDx against osteogenesis imperfecta and child abuse.
Osteopetrosis.
Osteoclast dysfunction is due to deficiency of carbonic anhydrase II. This enzyme inside osteoclasts normally allows osteoclasts to form H+ to resorb bone.
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Osteopetrosis.
Granulocyte-macrophage colony-stimulating factor (GM-CSF) causes the differentiation of osteoclast precursors into osteoclasts. This is asked on one of the Step 1 NBME forms, where they give osteopetrosis and ask something along the lines of, “The cell lineage that’s fucked up in this condition requires which of the following”àanswer = GM-CSF.
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Collagen I defect that results in recurrent fractures in a child;?????
Osteogenesis imperfecta.
Osteogenesis imperfecta. HY DDX?
important DDx are child abuse and osteopetrosis.
Osteogenesis imperfecta. Buzzy CP?
Blue sclerae too buzzy and often not mentioned.
Osteogenesis imperfecta. What CP? ent
Conductive hearing loss due to defective ossicles (middle ear bones).
Osteogenesis imperfecta. Many different types of OI, some resulting in miscarriage. Harder vignette can mention child with multiple fractures, where the mom has Hx of recurrent miscarriage.
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Connective tissue disorders. Marfan.
Autosomal dominant; chromosome 15, FBN1/2.
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Connective tissue disorders. Marfan. Codes for fibrillin, which is a glycoprotein that forms a sheath around elastin.
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Connective tissue disorders. Marfan.
Tall, lanky body habitus with flat feet, chest wall abnormalities (i.e., pectus excavatum or carinatum), flat feet (pes planus), scoliosis, mitral valve prolapse (mid-systolic click), increased risk for aortic dissection (can retrograde propagate toward aortic root, causing root dilatation and aortic regurgitation [decrescendo diastolic murmur]).
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Connective tissue disorders. Marfan.
Is not associated with berry/saccular aneurysms (unlike Ehlers-Danlos and ADPKD).
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Ehlers-Danlos. defect in what?
Defect in collagen III synthesis; can be written as “Defect in synthesis of fibrillar collagen.”
This can be confusing because fibrillin is completely unrelated and refers to Marfan syndrome. It is just coincidental that “fibrillar collagen” means type III collagen.
Ehlers-Danlos.
Wrong answer = “abnormal synthesis of extracellular glycoprotein” (refers to fibrillin for Marfan syndrome, which as mentioned above, is a glycoprotein that forms a sheath around elastin.
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Ehlers-Danlos. CP?
Presents as easy bruising + hyperextensible skin.
Williams. Autosomal dominant; chromosome 7.
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Williams. what defect?
Defect in elastin
Elfin-like facies, hypercalcemia, well-developed verbal skills.?
Williams.
Williams. CP?
Elfin-like facies, hypercalcemia, well-developed verbal skills.
Williams. what cardio pathology?
BUVO CMS!!!
Can cause supravalvular aortic stenosis.
