hypothyroidism Flashcards
Causes of secondary hypothyroidism (pathology at pituitary gland) (3)
- Compression from a pituitary tumour
- Sheehan syndrome
- Drug: cocaine, steroids, dopamine (all inhibit TSH secretion)
- pituitary surgery
- radiotherapy
- trauma
Complication of hypothyroidism (4)
Myxedema coma
- Often infection precipitated
- Rapidly drops T4
- Loss of consciousness, heart failure
Diagnosis of hypothyroidism (2)
- TFT (thyroid function test)
- Anti-TPO antibodies high
Epidemiology of hypothyroidism (2)
- Mainly >40 years
- F>M 6:1
Most common cause of hypothyroidism in the developed world (3)
- Hashimoto’s thyroiditis
- Autoimmune inflammation of the thyroid gland - initially cause a goitre
- Associated with anti-TPO antibodies and antithyroglobulin antibodies
Most common cause of hypothyroidism in the developing world
Iodine deficiency
Other causes of hypothyroidism (3)
- DeQuervain’s thyroiditis
- Post-thyroidectomy or post-radioiodine
- Drugs; amiodarone, lithium, carbimazole
Signs of hypothyroidism (5)
- Hair loss, dry and cold skin
- Bradycardia
- Goitre
- Decreased deep tendon reflexes
- Carpal tunnel syndrome
Symptoms of hypothyroidism (5)
- Cold intolerance
- Constipation
- Weight gain
- Lethargy
- Menorrhagia
TFTs for hypothyroidism (3)
- High TSH, low T4 = primary hypothyroid
- Low TSH, low T4 = secondary hypothyroid
- Normal/low TSH, Low T4 = hypopituitarism
Treatment for hypothyroidism
- Levothyroxine (T4)
- Titrate dose so you don’t induce iatrogenic hyperthyroidism
Treatment for myxedema coma (3)
- T3 orally or IV
- ABC approach Oxygen, gradual rewarming
- Cardiac output measures
- Hydrocortisone
- antibodies
- Glucose infusion
What is postpartum thyroiditis (3)
- Same mechanism as Hashimoto’s
- Acute: presents during pregnancy
- Resolves by itself within 1 year of symptoms
biochemical diagnosis / test reuslts of hypothyroidism
TSH high - FT4 low - primary
may be anaemic
elevated AST
elevated CK - associated myopathy
Lipids - Cholesterol and Triglycerides
Sodium - Hyponatraemia due to increase in ADH and impaired free water clearance
- Also think cortisol axis exclude Addison’s disease
hashimotos thyroiditis
Most common associated with autoantibodies
High TPO titre can be hypothyroid, euthyroid or go through a toxic phase: Hashi-toxicity
May have TSH Receptor blocking antibodies
Lymphoid infiltrations, rubbery, eventually fibrosis and atrophy
6x common in females increases with age
Associated with other autoimmune conditions pernicious anaemia, vitiligo etc
post partum thyroiditis
Transient following pregnancy: can cause hyper, hypo or be sequential
Self limiting usually
If antibodies may be rendered hypothyroid
complications with levothyroxine - what to be careful of when administering
- elderly and cardiac issues
- look for other autoimmune conditions eg addisons
- pregnancy as tetrogenic
outline site of pathology, TSH and T3/T4 levels of primary and secondary hypothyroidism.
primary:
- thyroid gland
- high TSH
- low T3 and T4
secondary:
- pituitary gland
- low TSH
- low T3/T4
what antibodies are associated with hypothyroidism?
- anti-TPO
- anti-Tg
causes of primary hypothyroidism
- hashimotos thyroiditis
- thyroid surgery
-radiation - iodine deficiency
- hyperthyroidism medications
iodine and hashitotos cause of goitre
iodine deficiency - causes goitre
hashimotos - causes initial goitre which leads to atrophy
levothyroxine
synthetic version of T4 which metabolises into T3
sheehan syndrome
anterior pituitary gland damage due to ishaemia
