Screening blood test if thyroid problems are suspected
TSH
*if abnormal, then do T3 and T4
Blood results in primary hypothyroidism (TSH and T3/T4)
Blood results (TSH and T3/T4) in secondary hypothyroidism
Blood results (TSH and T3/T4) in hyperthyroidism
Antibodies that are usually present in Grave’s and Hashimoto’s
- Antithyroid Peroxidase (anti-TPO) Antibodies - antibodies against the thyroid gland itself
- most relevant thyroid autoantibody in autoimmune thyroid disease
Antithyroglobulin Antibodies
- antibodies against thyroglobulin - a protein produced and extensively present in the thyroid gland
- limited use - can be present in normal individuals
- usually present in Grave’s Disease, Hashimoto’s Thyroiditis and thyroid cancer
Antibodies measured specifically in Grave’s disease
- 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
What is ultrasound imaging used for in thyroid?
- diagnosing thyroid nodules
- distinguishing between cystic (fluid filled) and solid nodules
- Ultrasound can also be used to guide biopsy of a thyroid lesion
Investigation of what (2) thyroid conditions is radioisotope scan used in?
- hyperthyroidism
- thyroid cancer
Principle behind radioisotope scan of the thyroid
- Radioactive iodine is given orally or intravenously
- it travels to the thyroid where it is taken up by the cells. Iodine is normally used by thyroid cells to produce thyroid hormones
- the more active the thyroid cells, the faster the radioactive iodine is taken up
Principles behind a gamma camera use in thyroid disease
- A gamma camera is used to detect gamma rays emitted from the radioactive iodine
- The more gamma rays that are emitted from an area the more radioactive iodine has been taken up
Gamma camera results. What diseases are they:
A. DIffuse high uptake
B. Focal high uptake
C. Cold areas
- 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
Meaning of:
A. Hyperthyroidism
B. Thyrotoxicosis
A. Hyperthyroidism: overproduction of thyroid hormone by the thyroid gland
B. Thyrotoxicosis: abnormal and excessive quantity of thyroid hormone in the body
Difference between a) primary b) secondary hyperthyroidism
a) primary hyperthyroidism -> thyroid gland itself behaves abnormally and produces excessive thyroid hormone
b) secondary hyperthyroidism -> thyroid gland produces excessive hormones as a result of overstimulation by TSH (pathology in hypothalamus or pituitary)
What’s pathophysiology of Grave’s disease
Autoimmune process -> TSH receptor antibodies are produced -> stimulation of thyroid gland to produce hormones
*TSH receptor antibodies mimic TSH
Another name for Toxic Multinodular Goitre
Toxic mutinodular goitre = Plummer’s disease
What happens in toxic nodular goitre? (pathophysiology)
nodules develop on the thyroid gland -> they act independently of a normal feedback system -> excessive thyroid hormone production
Which disease is exophthalmos seen in?
Grave’s
*inflammation, swelling and hypertrophy of a tissue behind eye -> exophthalmos
Pathophysiology of pretibial myxedema
- deposits of mucin
- under the skin of anterior tibia
- waxy discolouration, oedematous appearance
- seen in Grave’s disease (reaction to TSH receptor antibodies)
General symptoms of hyperthyroidism
- Anxiety and irritability
- Sweating and heat intolerance
- Tachycardia
- Weight loss
- Fatigue
- Frequent loose stools
- Sexual dysfunction
Unique features of Grave’s
These features all relate to the presence of TSH receptor antibodies:
- Diffuse Goitre (without nodules)
- Graves Eye Disease
- Bilateral Exopthalmos
- Pretibial Myxoedema
Unique features (3) of Toxic Multinodular Goitre
- Goitre with firm nodules
- Most patients are aged over 50
- Second most common cause of thyrotoxicosis (after Grave’s)
Solitary Toxic nodule
- what type of thyroid abnormality it would cause?
- pathophysiology
- management
- hyperthyroidism
- single abnormal thyroid nodule -> release thyroid hormone
Cause: thyroid benign adenoma
Management: surgical removal of the nodule
De Quervain’s thyroiditis
- features
Features: Presentation of viral infection (fever, neck pain, dysphagia) + features of hyperthyroidism
