08 Thyroid Disorders Quan Flashcards
What are the thyroid hormone functions?
Growth and development (long bone growth and neuronal maturation). Increase basal metabolic rate. Body temperature. Body homeostasis
What are the main steps in Thyroid Hormone Synthesis?
Hypothalamus releases thyrotropin-releasing hormone (TRH) to stimulate anterior pituitary. Pituitary releases thyroid stimulating hormone (TSH) to activate the thyroid gland. Thyroid gland produces T3/T4
For thyroid hormone regulation, what happens with Low T4/T3 levels?
Stimulates release of TRH from hypothalamus
For Thyroid Hormone Regulation, what happens with High T4/T3 levels?
Regulate negative feedback loop. Decrease production of TRH and TSH
What is Thyroxine?
T4
What is Triiodothyronine?
T3
What is the major circulating thyroid hormone?
T4, secreted by the thyroid
Which thyroid is more potent?
T3 is 4x more potent than T4
What is the half-life like for thyroid hormones?
T4 7 days. T3 1.5 days
What are the T3 concentrations like?
T3 has lower serum concentration than T4 (80% of T3 from T4 –> T3 conversion in the periphery)
What are the normal TSH concentrations?
0.5-5 milliinternational units/L
What are the TSH concentrations like in Hyperthyroidism?
Low
What are the TSH concentrations like in Hypothyroidism?
High
What are the normal Free T4 concentrations?
0.8-2.7 ng/dL
What are the Free T4 concentrations like in Hyperthyroidism?
High
What are the Free T4 concentrations like in Hypothyroidism?
Low
What are the normal Total T4 concentrations?
4.5-10.9 mcg/dL
What are the Total T4 concentrations like in Hyperthyroidism?
High
What are the Total T4 concentrations like in Hypothyroidism?
Low
What are the normal Total T3 concentrations?
60-181 ng/dL
What are the Total T3 concentrations like in Hyperthyroidism?
High or normal
What are the Total T3 concentrations like in Hypothyroidism?
Low or normal
What is the normal range for Thyroperoxidase (TPO)?
< 100 IU/mL
What are the normal Antithyroglobulin (ATgA) levels?
< 8%