Endocrinology - thyroid function tests Flashcards

1
Q

Hyperthyroidism thyroid function tests findings

A

Primary (thyroid gland problem):

  • High T3 and T4
  • Low TSH level

Secondary (to pituitary adenoma):

  • High T3 and T4
  • High TSH level
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2
Q

Hypothyroidism thyroid function tests findings

A

Primary (thyroid gland problem):

  • Low T3 and T4
  • High TSH level

Secondary (to pituitary adenoma):

  • Low T3 and T4
  • Low TSH level
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3
Q

Antibodies in thyroid disease

A

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.

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4
Q

Imaging in thyroid disease

A

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
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5
Q

Radioisotope scan findings and meanings

A

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

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