Hyperthyroidism Flashcards
State of thyroid hormone excess of ANY etiology
Thyrotoxicosis
State of thyroid hormone excess due specifically to excessive thyroid gland function
Hyperthyroidism
Primary thyroid disorder is a disorder that originates from the
thyroid gland
Secondary thyroid disorder is a disorder due to the stimulation of thyroid gland by excess
TSH
HCG
The most common cause of hyperthyroidism
Grave’s disease
Life-threatening exacerbation of hyperthyroidism
Thyroid storm
Throid crisis
Grave’s disease prevalence
Lifetime risk
Associated with increased intake of
Sex
Age
1%
Iodine intake
F>M 7-10:1
Rare before adolescence
Typical range: 20-50
May occur in elderly as “apathetic hyperthyroidism”
Most common etiology of thyrotoxicosis
Grave’s (60-80%)
Genetic risk factors for Grave’s
HLA DR
Cytotoxic T lymphocyte-associated antigen 4 variants
Protein tyrosine phosphatase-22 (PTPN22)
A cell regulatory gene
PTPN22
Monozygotic concordance of Grave’s
Dizygotic twin concordance of Grave’s
20-30%
<5%
Smoking in
Grave’s
Ophthalmopathy
Minor risk factor for Grave’s
Major risk factor for ophthalmopathy
Sudden increase in dietary iodine intake
Radiocontrast materials containing high iodine content
Medications (amiodarone)
Iodine intake
Grave’s
3 fold increase in Grave’s
Postpartum
Grave’s disease is caused by thyroid-stimulating
immunoglobulin against the thyrotropin TSH receptor
Antibodies against the thyrotropin TSH receptor in Grave’s cause
Autonomous growth of thyroid
Autonomous production of thyroid hormones
Intrathyroidal inflammatory cells in Grave’s produce cytokines:
IL-1
TNF a
IFN a
cytokines help sustain intrathyroidal autoimmune process
IL-1
TNFa
IFNa
induce expression of
adhesion
regulatory
HLA II
which in turn activate local inflammatory cells
Edema
Inflammation of EOM
Increase in orbital connective tissue and fat
Thyroid-associated ophthalmopathy
Edema in Grave’s ophthalmopathy is due to hydrophilic action of
secreted by
Glycosaminoglycans
Fibroblast
Inflammation in Grave’s ophthalmopathy is due to infiltration of EOMs and orbital connective tissue by
lymphocytes
macrophages
Thyroid associated opthalmopathy may result from immunoglobulins directed to specific antigens ie
thyrotropin TSH receptors on preadipocyte subpopulation of orbital FIBROBLASTS
Lymphocytic infiltration of dermis
Accumulation of glycosaminoglycans
Non-pitting edema
Dermopathy
Pretibial myxedema
Unusual disorder associated with
hyperthroidism
sporadic episodes of acute muscle weakness
hypokalemia
Asian men
Prodrome: muscle ache, stiffness, LE proximal muscle weakness progressing to flaccid quadriplegia
Serum K not always below normal
Subtle hyperthyroidism symptom
Thyrotoxic period paralysis
Tx: K supplement