Graves' Orbitopathy Flashcards
What is the incidence of Graves’ Orbitopathy (GO)?
Estimated incidence of GO is 16 women or 3 men per 100,00
= Women affected 5x more than men
Approx. 400,000ppl in the UK with GO
Why may have Graves’ Orbitopathy prevalence reduced?
Risk factors such as smoking and employment may have been the cause for the reduction in GO over the years
What is the thyroid gland?
Butterfly shaped gland in the lower neck anterior to the trachea between the SCM muscles that’s a highly vascular endocrine organ consisting of densely packed follicles
What is the function of the Thyroid Gland?
- Concentrates iodide to form thyroid hormones
- Thyroid hormones synthesised and stored in the follicles
What stimulates the release of TSH?
TRH in the hypothalamus to the pituitary gland to the thyroid gland
Where is TSH secreted?
Anterior pituitary
What does TSH stimulate secretion of?
T3 - Tri-iodothyronine
T4 - Tetra-iodothyronine (Thyroxine)
T3 & T4 secreted into bloodstream (bound to plasma proteins and free form intracellular)
What growth and development role do thyroid hormones have?
- Help regulate rate of growth of many tissues
- Maturation of CNS and bones
- Regulation and synthesis of some respiratory enzymes
What Metabolic effects do thyroid hormones have?
Regulate:
- Basal metabolic rate
- Water & ion transport
- Calcium & phosphorus metabolism
- Cholesterol & fat metabolism
- Nitrogen metabolism
What is the main sign and symptom of Hyperthyroidism?
As the thyroid is overactive in hyperthyroidism this leads to an enlarged thyroid gland (‘Goitre’)
What is ‘Goitre’?
Enlarged thyroid gland
What are the signs and symptoms of hyperthyroidism following goitre?
As goitre can lead to overproduction of hormones it can lead to:
- Abnormal heart rhythms – tachycardia
- Increased appetite but may have weight loss
- Hand tremors
- Fine brittle hair
- Hyperactivity
- Heat intolerance and increased perspiration – warm, moist skin
- Lighter or less frequent periods
- Irritability
- Anxiety
- Muscle weakness – upper arms and thighs
What are the signs and symptoms of Hypothyroidism?
An under-active thyroid can lead to:
- Fatigue, exhaustion
- Feeling run down and sluggish
- Unexplained / excessive weight gain
- Dry, coarse, itchy skin and hair
- Slow heart rate
- Feeling cold – especially in the extremities
- More frequent periods, increased menstrual flow
- Difficulty concentrating – brain fog
- Hoarse voice
- Muscle cramps
How do we diagnose thyroid abnormalities?
- Blood test for TSH – (considered outside normal if lower than 0.3 or higher than 3.0)
- Blood test for Thyroid-stimulating immunoglobulin (TSI)
- Blood test for Anti-thyroid antibodies
- Calculated free T4 index (10-20 pmol/L)
- Serum T3 (2.5 – 5.3 pmol/L)
- Normative values often vary based on location so always best to speak to a medic about this if further information required!
What drugs can we used for treating hyperthyroidism?
- Thinomines
- Steroids
- Immunosuppressants
- Radioactive Iodine
What are the types of thinomines and what are they for?
They’re for treating hyperthyroidism
Carbimazole, Methamizole, Propylthiouracil
What do Thinomines do and how do they work??
For reducing hyperthyroidism
- Interfere with thyroid hormone synthesis by blocking the build up of iodine. Most effective if the onset of disease within 1 year
What steroids can we use in hyperthyroidism?
Oral Prednisolone
How do steroids (oral prednisolone) help with hyperthyroidism?
By decreasing secretion of thyroid hormones and peripheral conversion of T4 and T3. Used in severe cases
What are the types of immunosuppressants used in hyperthyroidism?
Azathioprine or Rituximab
How often are immunosuppressants used in hyperthyroidism?
Very rarely - mainly used for comorbidities
How is Radioactive Iodine used in hyperthyroidism?
- Radioactive iodine introduced to the body and taken up by the thyroid gland. Normal cell division and function is disturbed.
Who is radioactive iodine used in most commonly?
Hyperthyroid patients over 45 years of age or in younger patients if other treatments are contraindicated
What are some drawbacks to radioactive iodine?
- 20% of patients become hypothyroid within 1 year of the treatment (after hyperthyroid treatment using radioactive iodine)
- Ocular symptoms have been found to worsen following this treatment (Acharya 2008)