Thyroid / parathyroid function tests Flashcards
What does the hypothalamus release in the thyroid axis?
Thyrotropin-releasing hormone (TRH)
What does TRH do?
Stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH)
What does the anterior pituitary release in the thyroid axis?
Thyroid-stimulating hormone (TSH)
What does TSH do?
Stimulates the thyroid gland to release triiodothyronine (T3) and thyroxine (T4)
What does the thyroid gland release in the thyroid axis?
Triiodothyronine (T3) and thyroxine (T4)
What is the role of T3 and T4 in the thyroid axis?
They suppress the release of TRH and TSH
What will primary hyperthyroidism show on thyroid function tests?
Low TSH
High T3 and T4
What will secondary hyperthyroidism show on thyroid function tests?
High TSH
High T3 and T4
What will primary hypothyroidism show on thyroid function tests?
High TSH
Low T3 and T4
What will secondary hypothyroidism show on thyroid function tests?
Low TSH
Low T3 and T4
What conditions are anti-thyroid peroxidase antibodies (anti-TPO) usually present in?
Graves disease
Hashimoto’s thyroiditis
What conditions are anti-thyroglobulin antibodies (anti-Tg) usually raised in?
Graves disease
Hashimoto’s thyroiditis
Thyroid cancer
What condition is caused by TSH receptor antibodies?
Grave’s disease
What scan is used to investigate hyperthyroidism and thyroid cancers?
Radioisotope scan
What type of ray is emitted from iodine in a radioisotope scan?
Gamma rays
In which condition(s) is there diffuse high uptake of iodine?
Grave’s disease
In which condition(s) is there a focal high uptake of iodine?
Toxic multinodular goitre
Adenomas
In which condition(s) is there ‘cold areas’ on a radioisotope scan?
Thyroid cancer
What will subclinical hyperthyroidism show on thyroid function tests?
Low TSH
Normal T3 and T4
What will primary hyperparathyroidism show in PTH and calcium levels?
High PTH
High calcium
What will secondary hyperparathyroidism show in PTH and calcium levels?
High PTH
Low / normal calcium
What will tertiary hyperparathyroidism show in PTH and calcium levels?
High PTH
High calcium
