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 in primary hypothyroidism
- FT4 low confirms this
Anaemia
- Normochromic normocytic, can be macrocytic think B12, microcytic
AST
- Aspartate transferase levels can be elevated from liver or muscle
CK
- Elevated with the 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
