For the following thyroid diseases, predict the relative expected blood values for TSH, T4, T3- Uptake, and FTI:
- Cretinism and Myxedema
- Secondary Hypothyroidism
- Tertiary Hypothyroidism
- Hashimoto’s Disease
- Simple Goiter
- Grave’s Disease
- Toxic Goiter due to benign tumor
- Secondary Hyperthyroidism
- Cretinism and Myxedema - Primary Hypothyroid Conditions. TSH ↑. Everything else ↓.
- i. Cretinism: neonatal hypothyroidism resulting in mental retardation, voice changes (cat-like cry) pointy ears, and dwarfism. Screened for immediately after birth. Synthroid T4 therapy prevents the disease if present.
- ii. Myxedema: idiopathic adult hypothyroidism. Results in coarsening of the skin, puffiness of the skin of face, hair loss, skin legions, run-down, narcolepsis. Hereditary. It is the most common hypothyroid disease, and fully treatable with T4 therapy.
(Pituitary failure). Relatively rare. TSH ↓. Everything else ↓.
(Hypothalamus failure) Very rare. TSH ↓. Everything else ↓. Stimulation test to determine whether it is pituitary or hypothalamus.
- Hashimoto’s Disease (Chronic Thyroiditis)
- i. Autoimmune disease that slowly destroys the thyroid gland. Initially euthyroid pattern that becomes a hypothyroid pattern.
- ii. Thyroglobulin is the initial initiator of the immune response. Gobs leak out into the blood and represents a foreign protein to the immune system since levels are usually so low. As thyroid cells are damaged, more antigens are exposed and more antibodies are produced…
- iii. Quantitate Anti-Tg (Thyroglobulin) Antibodies in the blood. Can also quantitate the other antibodies to other parts of the thyroid to keep track of progression of treatment.
- iv. Early stages: everything normal except Anti-Tg elevating.
- v. Later stages: TSH High. T4, T3, FTI, T3-uptake ↓. Anti-Tg, Anti-TPO, TMAB ↑.
- Simple (Endemic) Goiter
- i. Caused by low levels of iodine, and has nearly disappeared in US where iodine is added to salt, but still exists in the world where seafood and iodinized salt is unavailable.
- ii. Overstimulation of thyroid gland causes hypertrophy; however, T3 and T4 are still low because the iodine is not available to make these hormones. TSH ↑. T4, T3, FTI, T3-uptake ↓.
- iii. Primary hypothyroid disease with goiter.
- Grave’s Disease (Exophthalmic Goiter) – characterized by bug eyes from fat deposits behind eyes pushing the eyes out.
- i. Most common form of hyperthyroidism.
- ii. TSH-receptor antibodies stimulate thyroid the way TSH would, causing over production of T3 and T4. TSH ↓. T4, T3, TFI, T3 Uptake ↑.
- iii. Without treatment, exopthamic (eye) condition will cause eyes to rupture, resulting in blindness. They also have a goiter.
- iv. Treatment with anti-thyroidal drugs (similar to iodine, used to make nonfuctional T3 and T4), plasmapheresis, or radiation therapy to destroy thyroid gland (with radioactive I) and then administer synthetic hormone.
- Toxic Goiter due to benign tumor (Thyrotoxicosis)
- i. Caused by one or more benign tumors of the thyroid which overproduce hormones (nodular goiter – nonsymmetrical). Usually does not cause exophthalmic condition.
- ii. Primary hyperthyroid condition. TSH ↓. T4, T3, FTI, T3 Uptake ↑.
- Secondary Hyperthyroidism (Pituitary microadenoma) – fairly uncommon.
- i. Caused by a microadenoma (pituitary tumor), which usually produces more hormones than just TSH. Tumor may be visible on CATscan. TSH ↑. T4, T3, FTI, T3 Uptake ↑.
– Thyroglobulin elevates in the blood in Grave’s Disease, Hashimoto’s, Thyroiditis, Benign and Melignant Thyroid tumors, as well as from physical trauma to the thyroid. It is most helpful as a disease marker. Blood levels relate to progression and severity of disease.