Endocrine Function II Flashcards
List the thyroid hormone secreted in the greatest quantity.
T-4 is the main secretory product
List three thyroid binding proteins.
1 Throxine Binding Globulin (TBG)
2 Transthyretin (Thyroxine Binding Prealbumin) (TBPA)
3 Albumin
List the most potent, biologically active thyroid hormone.
T-3
Describe the structure and clinical significance of increased levels of reverse T-3.
biologically inactive form favored under stress
What is the cause of hyperthyroidism in Graves’ Disease?
autoimmune etiology; autoantibodies bind to TSH receptors in thyroid; the body thinks it is getting TSH but it is fooled by antibodies
What is the cause of hyperthyroidism in toxic multinodular goiters?
discrete portions of thyroid not under normal feedback control; no exophthalmopathy but still producing thyroid hormone
What is the cause hyperthyroidism in solitary toxic adenoma?
patients have thyroid nodules that avidly concentrate injected radioactive iodine; this benign tumor does not respond to normal feedback control
These are nodules concentrate injected radioactive iodine.
hot nodules
What causes hyperthyroidism in subacute thyroiditis?
inflammation of the thyroid gland; appears to be viral in origin; follicles become inflamed and disrupted
What causes hyperthyroidism in iatrogenic symptoms?
adverse mental or physical conditions caused by a medical procedure/physician
What causes hyperthyroidism in factitious symptoms?
Disorders that are not genuine or natural; physical or psychological symptoms are produced under the voluntary control of the patient
What causes hyperthyroidism in TSH-dependent hyperthyroidism?
caused by excess placental hormones (hCG) and TSH-secreting pituitary tumors (tertiary in hypothalamus)
List some symptoms associated with hyperthyroidism
heat intolerance, flushing, perspiration, increased appetite, weight loss, tachycardia, SOB, nervousness
List typical T-4, T-3, TSH, and/or TRH levels
-Graves’ Disease
Increased T-3/T-4 and Decreased TSH
List typical T-4, T-3, TSH, and/or TRH levels
-Toxic multinodular goiter
Increased T3/T4 and decreased TSH
List typical T-4, T-3, TSH, and/or TRH levels
-Solitary toxic adenoma
Increased T3/T4 and Decreased TSH
What are the five causes of adult hypothyroidism?
intrinsic disease of the thyroid, total thyroidectomy, complete blockage of thyroid function by irradiation or an antithyroid drug, or various diseases
What is the cause of hypothyroidism in cretinism?
failure to develop a thyroid gland in utero; if mother receives antithyroid drugs or radioactive iodine during pregnancy; if maternal antithyroid antibodies cross placenta (results in mental retardation)
What causes hypothyroidism in Hashimoto’s thyroiditis?
most common cause of hypothyroidism; autoimmune, chronic inflammatory disease of thyroid in which T-helper cells stimulate B-lymphs to produce antithyroid antibodies; defect in organification, causing lymphocytic infiltration of thyroid; makes antibodies against thyroid tissues
What symptoms are associated with hypothyroidism?
more common in women; cold intolerance, dry skin, decreased appetite, muscle weakness, slow heart rate, low blood pressure, weight gain, and hoarseness
What are typical T3/T4, TSH, and/or TRH levels for hypothyroidism?
decreased T3/T4, increased TSH (primary); decreased T3/T4, decreased TSH (secondary/tertiary)
What is the most common cause and typical total T4 and TSH levels in euthyroid “sick” syndrome?
Caused by Increase in level of serum binding proteins in certain diseases; no evidence of thyroid diease; decreased T3/T4 and normal TSH
Differentiate TSH levels associated with hypothyroid vs euthyroid “sick” patients.
Hypo: increased TSH, decreased T3/T4; Euthyroid: increased reverse T3, decreased T3/T4, normal TSH (increased with treatment), no signs/syptoms, normal thyroid
