Endocrinology - thyroid function tests Flashcards
Hyperthyroidism thyroid function tests findings
Primary (thyroid gland problem):
- High T3 and T4
- Low TSH level
Secondary (to pituitary adenoma):
- High T3 and T4
- High TSH level
Hypothyroidism thyroid function tests findings
Primary (thyroid gland problem):
- Low T3 and T4
- High TSH level
Secondary (to pituitary adenoma):
- Low T3 and T4
- Low TSH level
Antibodies in thyroid disease
Anti-TPO (Antithyroid Peroxidase) Antibodies
- Most relevant autoantibody
- Usually present in Grave’s disease and Hashimoto’s thyroiditis
Antithyroglobulin antibodies
- Usually present in Grave’s Disease, Hashimoto’s Thyroiditis and thyroid cancer
- But can be present in normal individuals
TSH receptor antibodies -autoantibodies that mimic TSH, bind to the TSH receptor and stimulate thyroid hormone release. They are the cause of Grave’s Disease and so will be present in this condition.
Imaging in thyroid disease
Thyroid ultrasound
- Useful for diagnosing thyroid nodules
Radioisotope scan
- Used to investigate hyperthyroidism and thyroid cancers
- Radioactive iodine given and taken up by thyroid
- Gamma camera used to detect gamma rays emitted from the radioactive iodine
Radioisotope scan findings and meanings
Diffuse high uptake is found in Grave’s Disease
Focal high uptake is found in toxic multinodular goitre and adenomas
“Cold” areas (i.e. abnormally low uptake) can indicate thyroid cancer