Pathophysiology of Graves Disease
1)Â Graves disease is marked by hyperfunctioning of thyroid gland owing to stimulation by autoantibodies
2) has exacerbations and remissions
3) if untreated, leads to eventual thyroid failure
Signs and Symptoms
1) fine hair
2) muscle wasting
3) exophthalmos
4) pretibial myxedema
5) fatigue/weakness
6) palpitations/nervousness/tremor/sweating
7) diffuse goiter
8) emotional lability
9) weight loss
10) tachycardia
11) bruit and thrill over thyroid
12) some Graves disease patients can have loss of eyebrows particularly laterally in the later stages of the disease
Characteristic Test Findings
Laboratory
1) heterogenous autoantibodies to TSH receptors (some of which are IgG)
2) increased T3
3) increased T4
Nuclear Medicine
4) increased radioiodine uptake by thyroid
Histology/Gross Pathology
1) grossly symmetrical enlarged thyroid (diffuse thyroid hyperplasia)
2) cut surface is firm and beefy
3) highly vascular
4) enlargement of extraocular muscles
5) decrease of stored colloid
Associated Conditions
1) atrial fibrillation
2) pernicious anemia
3) Hashimoto’s thyroiditis
4) increased frequency of HLA-B8 and HLA-DR3 in white patients
5) increased incidence in smokers with particularly serious eye sequelae
Biochemistry
1) Type II hypersensitivity reaction
2) defect in antigen-specific suppressor T cells
3) sensitization to antigens of Yersinia enterocolitica plays a role
Inheritance/Epidemiology
1) female to male, 9:1
2) affects 2-4% of USA population sometime during their lifetime
3) in women, onset is during puberty, pregnancy, and menopause
4) onset in men is in old age
Treatment
1) destruction with radioactive iodine
2) anti-thyroid medication to temporize Graves disease
3) exophthalmos does not always reverse
Tips for USMLE
1) key pathologic fact of Graves disease is the presence of antibodies against the TSH receptors that mimic TSH and cause overstimulation of the thyroid
2) another term for these autoantibodies is long-acting thyroid stimulator (LATS)
3) other causes than Graves disease of exophthalmoos are orbital dermoid cysts and hemangiomas
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