Thyroid Pathology Flashcards
What vertebral level is the thyroid gland at?
C6-T1
What lobe may or may not be present due to anatomical variation?
Pyramidal lobe
What is the blood supply to the thyroid gland?
Superior and inferior thyroid arteries:
Superior = from external carotid
Inferior = from right subclavian
What is the venous drainage of the thyroid gland?
Superior, middle and inferior thyroid veins:
Superior and middle = into internal jugular (then brachiocephalic)
Inferior = directly into brachiocephalic
What hormones are secreted by the thyroid gland?
T3/4/Thyroxine (from follicular cells),
Calcitonin (from parafollicular cells)
What substance is added to convert T3 - T4?
Iodine
What is the role of thyroid hormones?
Increase metabolic rate, increase thermogenesis, required for growth and development
How is most thyroxine transported in the blood?
Bound to thyroxine binding globulin
What is the most biologically active form of thyroxine?
T3 (de-iodinated at cells by enzymes from T4-T3)
What is the system of release of thyroxine (negative feedback)?
TRH (hypothalamus) -
TSH (pituitary) -
T3/4 (thyroid)
What is the autoimmune cause of hypothyroidism?
Hashimotos
What are the results of investigation of primary hypothyroidism?
Low fT3/4, high TSH (due to failure at thyroid gland)
Hashimoto’s: anti TPO antibodies
What are the investigation results of secondary hypothyroidism?
Low fT3/4, low TSH (failure at pituitary or hypothalamus)
What is goitrous hypothyroid due to?
Hashimoto’s thyroiditis (chronic)
What is the cause of non-goitrous thyroiditis?
Atrophic
How does hypothyroidism present?
Coarse sparse hair, more common in women, puffy eyes, cold intolerance, overweight, bradycardia, constipation
How is hypothyroidism treated?
Levothyroxine
What is a myxoedema coma?
Severe consequence of untreated hypothyroidism - medical emergency requiring intensive care
What is the autoimmune cause of hyperthyroidism?
Graves disease
What are the main causes of hyperthyroidism?
Autoimmune, toxic solitary nodule, toxic multi nodular goitre
How does hyperthyroidism present?
Weight loss, heat intolerance, palpitations/AF, anxiety/nervousness, diarrhoea, muscle weakness, tremor/sweating
What are the clinical signs of Graves disease?
Women, young, eye disease, pretibial myxoedema, thyroid bruits
How is hyperthyroid diagnosed?
Raised fT3/4, decreased TSH
Graves: anti-TPO antibodies
How is a nodular thyroid disease diagnosed?
High uptake or irregular scintigraphy (thyroid uptake) scan
What is the first and second line treatment of hyperthyroidism?
Carbimazole
Propylthiouracil (PTU)
What risk is associated with hyperthyroid treatment and how is this managed?
Agranulocytosis
If have severe sore throat and fever immediately stop medication and do FBC
What are the types of differentiated thyroid cancer?
Papillary (most common) and follicular
What is the prognosis of thyroid cancer?
Very good
How does thyroid cancer present?
Asymptomatic, more common in women, palpable nodules
How is thyroid cancer diagnosed?
Ultrasound guided FNA (fine needle aspiration)
NO thyroid isotope scan/CT/MRI
How is a thyroglossal cyst identified and managed?
Moves with the tongue when you stick it out, usually benign so just reassure
What is a thyroid storm?
Inadequately treated thyrotoxicosis - medical emergency
