15.3 - 15.6 Thyroid Flashcards
Cystic dilation of thyroglossal duct remnant
Thyroglossal duct cyst
Normally, the thyroid develops WHERE before traveling along the thyroglossal duct to the anterior neck
Back of tongue
What normally happens to the thyroglossal duct after the thyroid travels down it?
normally involutes, but if it persists, it may undergo cystic dilation
Persistance of thyroid tissue at the base of tongue (presents as mass at base of tongue)
Lingual thyroid
How does hyperthyroidism lead to increased BMR?
increased synthesis of Na+-K+ ATPase
How does hyperthyroidism lead to increased SNS activity?
increased expression of beta1-adrenergic receptors
cholesterol levels in hyperthyroidism
low
serum glucose in hyperthyroidism
high due to increased gluconeogenesis and glycogenenolysis
What type of autoantibody stimulates TSH receptor in Graves dz?
IgG
What type of HSR is Graves disease?
Type II HSR
HSR that is anaphylactic and atopic - free antigen cross-links IgE on presensitized mass cells and basophils, triggering release of vasoactive amines (histamine) that act at post capillary venules. Rxn develops rapidly after antigen exposure because of preformed antibody
Type I HSR
HSR that is cytotoxic (antibody mediated) - IgM, IgG bind to fixed antigen on “enemy” cell, leading to cellular destruction through 3 mechanisms
- opsonization leading to phagocytosis or complement activation
- complement-mediated lysis
- antibody-dependent cell-mediated cytotoxicity (ADCC), usually due to NK cells
Type II HSR
HSR that is immune-complex mediated - antigen-antibody (IgG) complexes activate complement which attracts PMNs, wh/ release lysosomal enzymes
Type III HSR
HSR that is delayed (T-cell-mediated) type - sensitized T lymphocytes encounter antigen and then release lymphokines (leads to macrophage activation; no antibody involved)
Type IV HSR
How do you test for type I HSR?
skin test for specific IgE
How do you test for type II HSR?
direct and indirect Coombes
How do you test for type III HSR?
immunofluorescent staining
How do you test for type IV HSR?
patch test, PPD
Muscle mass in hyperthyroidism
Decreased –> weakness