Thyroid Lecture Flashcards
1
Q
Anatomy of thyroid gland
A
- 2 lobes
- Isthmus connects
- Over trachea, just below cricoid cartilage, extends up to base of thyroid cartilage
- Develops from floor of pharynx
- Descends –> thyroglossal duct
2
Q
Phsyiology of thyroid gland
A
- Iodine is substrate for hormone synthesis
- Thyroid produces all circulatory T4 and 20% T3 (remainder is converted from T4 in extraglandular tissue)
3
Q
How is T3 and T4 transported?
A
- Almost entirely bound
- Proteins such as TBG, TTR and albumin
Thyroxine binding globulin, transthyretin
4
Q
What form of thyroid hormone is able to act on tissues?
A
Only free hormone
5
Q
Revise thyroid function test results
A
:)
6
Q
Causes of low or normal TSH with low T3/T4
A
- Central hypothyroidism - pituitary problem
- Isolated TSH deficiency
- Assay interference
- Non-thyroid illness
7
Q
Causes of high or normal TSH with high T3/T4
A
- Assay inteference
- Thyroxine replacement therapy
- Drugs eg amiodarone and hepatin
- Non thyroid illness
- TSH secreting pituitary adenoma
- Reistance to thyroid hormone
- Disorders of thyroid hormone transport/metabolism
8
Q
Specifc signs of Graves
A
- Eye disease - lid retraction, exopthalmos, paralysis of eye muscle
- Dermopathy
- Acropachy
- Lymphoid hyperplasia
Dr Omer said Graves is only one to have skin and/or eye disease
9
Q
Symptoms of thyrotoxicosis
A
- Palpitations
- Shaking
- Sweating
- Dyspnoea
- Weakness
- Diarrhoea
- Dysmenorrhoea
- Heat intolerance
- Weight loss
- Irritable
- Insomnia
10
Q
Signs of thyrotoxicosis
A
- Tachycardia/AF
- Tremor
- Hyperkinesia
- Hyper-reflexia
- Palmar erythema
- CHF
- Chorea
- Period paralysis
- Psychosis
- Goitre
11
Q
Causes of thyrotoxicoss - primary
A
- Graves disease
- Hashitoxicosis (hyperthyroid phase of those with Hashimotos thyroiditis)
- Nodular thyroid with autonomous function
- Thyroiditis
12
Q
Causes of thyrotoxicosis - secondary
A
- Pituitary TSHoma
- Thyroid hormone resistance
13
Q
How else can thyrotoxicosis occur?
A
- Overtreatment for hypothyroidism
- Thyrotoxicosis factitia - accidental/deliberate thyroxine ingestion
- Ectopic - trophoblastic tumours, stoma ovari
14
Q
Thyrotoxicosis diagnostic pathway
A
- Check TSH, T4, T3
- Check TSH receptor antibodies
- If present= Graves if not –> Technitium scan to see uptake
- Increased = Graves
- Patchy/single nodule = toxic multinodular goitre/toxic nodule
- Reduced = thyroiditis
15
Q
Treatment for Graves thyrotoxicosis
A
- Either dose titration or block and replace:
- Carbimazole - 1st line
- Propylthiouracil - used in pregnancy
- Beta blockers - propranolol