Hypothyroid tests include a TSH (Thyroid Stimulating Panel), T4 (Thyroxin) and aT3 (Triiodothyronine). Also, a thyroid palpation exam includes feeling orpalpating the thyroid to check for size of thyroid, uniformity and to feel if there are any nodules present. A sonogram may also be performed for diagnostic purposes such as detecting any nodules that may have not been felt by the physical exam.
The regulation of the thyroid gland occurs through a feedback system that has three regulating mechanisms.
Hypothalamus-Thyrotropin-Releasing Hormone (TRH)
TRH → stimulates the release of Thyroid Stimulating Hormone (TSH)
Pituitary gland→produces TSH that is sent to the thyroid gland
Thyroid gland→ produces T3 and T4 which gives “negative feedback” to the pituitary gland to either increase or decrease production of TSH.
So, increased levels of free T3 and T4 hormones decrease TSH secretion and in turn decreased levels of free T3 and T4 cause an increased secretion of the Thyroid Stimulating Hormone.
Three types of Hypothyroidism
1. Primary-failure of the thyroid to secrete hormone-this occurs in 95% of cases
2. Secondary– TSH secretion failing by the pituitary gland
3. Tertiary– TRH secretion deficiency by the hypothalamus
Primary Hypothyroidism-Thyroid tests-Laboratory
Serum free T4-normal→ 4-12mg/dl- this level is decreased in primary hypothyroidism.
TSH-normal→0.5-5.0mg/dl- this level is increased in primary hypothyroidism.
T3 Uptake-normal→25-35%-this level is below 25% primary hypothyroidism.
Serum cholesterol -normal- (200 or less mg/dl)- level is increased
Triglycerides- (150 or less mg/dl)- level is also increased
Hemoglobin-primary hypothyroidism can cause anemia which is a decrease of erythrocyte and/or hemoglobin in the blood. Anemia in hypothyroidism often occurs from the chronic disease due to reduced stimulation of erythropoietin secretion.
The gland, butterfly in shape, is about 5cm long and 3cm wide. The thyroid ultrasound test is noninvasive and it distinguishes between a cyst and a solid tumor.
Cysts have a smooth border and tumors (adenomas/carcinomas) are solid or well demarcated areas. If a tumor is suspected, a biopsy is performed.
Hashimoto’s is an autoimmune disorder and inflammatory process causing a goiter and eventually hypothyroidism. The antibodies that are elevated in Hashimoto’s Thyroiditis are the antithyroglubin and the antimicrosomal antibodies. Both antibodies do not have to be elevated to detect Hashimoto’s
The doctor may perform a variety of tests to obtain a true picture of how hypothyroidism is affecting the body.