lecture 9: metabolic disorders Flashcards
metabolic disorder
a disorder pertaining to nutrition, often caused by poor dietary intake or nutrient absorption
anemia
general term for various red blood cell conditions affecting oxygen exchange in body
congenital anemia
i.e sickle cell, thalassemia. genetic condition affecting hemoglobin synthesis. homozygous often fatal, heterozygous often advantageous
acquired anemia
reduced hemoglobin level or RBC counts due to poor nutrition, other pathological factors, or environment
thalassemia
a group of anemic conditions characterized by deficient hemoglobin production
thalassemia major
high mortality rate. especially in infants and children with extensive skeletal involvement
thalassemia in subadults
- thickening of bones due to enlargement of marrow spaces
- abnormal ephiseal fusion
- involvement of facial bones
- decreased vertebral height
sickle cell anemia
- abnormal hemoglobin S gene
- in homozygous form, any hypoxemic stress can cause crystallization of the abnormal hemoglobin and RBC distortion
- heterozygous form often protects against malaria
how does sickle cell anemia affect the bones?
1) secondary response to expansion of hemopoietic marrow 2) areas of necrosis due to vascular disruption 3) secondary infection due to vascular disruption
1) secondary response to expansion of hemopoietic marrow
thickening of cranial vault, frontal bone, long bones, phalanges and vertebrae
2) areas of necrosis due to vascular disruption
- large and small areas of necrotic bone formation; multiple or spotty
- femoral head most commonly affected
3) secondary infection due to vascular disruption
associated with areas of necrosis
iron deficiency anemia
caused by iron deficiency in the body
2 ways body becomes iron deficient
1) heavy loss (bleeding etc.) 2) poor intake/nutrition/absorption
porotic hyperostosis/ cribra orbitalia
iron deficiency anemia causes areas of marrow expansion in cranium
- characterized by thickening of diploe
- evidence of “hair on end” orientation of trabeculae
what do porotic hyperostosis and cribra orbitalia indicate?
- congenital anemia, iron deficiency
- several other conditions (infectious, metabolic, vascular and neoplastic)
scurvy
deficiency in vitamin C intake
- high mortality when severe
- categorized by livers inability to synthesize ascorbic acid
infantile scurvy
1) Direct effects of vitamin C deficiency
- decreased mechanical stability
- decrease in osteoblasts
- continuation of osteoclasts and chrondroclasts
2) secondary changes due to trauma
- fractures, dislocation, hemorrhage
infantile scurvy on skull
-porous hypertrophic bone formation due to chronic bleeding
IS on ribs
fracture of osteochondral junction and posterior migration of sternum and costal cartilage
IS on long bones
metaphyseal fractures, epiphysial dislocation, cortical thinning
IS on scapula
porosity
Adult scurvy traits
- less chance for skeletal lesions as person ages
- ribs fracture at osteochondral junction
- inflammation of alveolar bone and tissue due to chronic gingival hemorrhage
vitamin D deficiency
poorly mineralized bone is prone to deformity and fracture from mechanical stress
Rickets
- chronic vitamin D deficiency in early childhood
- usually not before 4 months of age but quickly affects growing bones
- accumulation of unmineralized bone and osteoid
what do Rickets bone lesions reflect?
1) direct affects of metabolic disturbances 2) secondarty deformities 3) growth reduction
How does rickets affect the cranium?
1) Craniotabes: thinning and softening of cranial vault
2) Cranial Base: superior displacement
3) cranial vault and base: deposition of finely porous subperiosteal bone
