Hypothyroidism (myxoedema)

Question 1

What are the symptoms of hypothyroidism?

Answer 1

• Tiredness
• Sleepy
• Lethargic
• Decreased mood
• Cold intolerance
• Increased weight
• Constipation
• Menorrhagia
• Hoarse voice
• Decreased memory/cognition
• Dementia
• Myalgia
• Cramps
• Weakness

Question 2

What are the signs of hypothyroidism?

Answer 2

• BRADYCARDIC
• Dry thin hair/skin
• Yawning
• Cold hands
• Ascites
• Round puffy face/double chin/obese

Question 3

How is hypothyroidism diagnosed?

Answer 3

• Raised TSH
• Low T3 and T4
• Raised cholesterol and triglyceride
• Macrocytosis

Question 4

What are the causes of primary autoimmune hypothyroidism?

Answer 4

• Primary atrophic hypothyroidism
• Hashimoto’s thyroiditis

Question 5

What is Hashimoto’s thyroiditis?

Answer 5

• Hashimoto’s thyroiditis, also known as chronic lymphocytic thyroiditis, is the most common cause of hypothyroidism in the United States.
• It is an autoimmune disorder in which antibodies directed against the thyroid gland lead to chronic inflammation.

Question 6

What are the other causes of primary hypothyroidism?

Answer 6

• Iodine deficiency
• Post-thyroidectomy or radioiodine treatment
• Drug-induced
  
  • Anti-thyroid drugs
  • Amiodarone
  • Lithium
  • Iodine
• Subacute thyroiditis

Question 7

What are the causes of secondary hypothyroidism?

Answer 7

• Not enough TSH - very rare

Question 8

What are some hypothyroidism’s associations?

Answer 8

• Other autoimmune diseases
  
  • T1DM
  • Addisons
• Turners syndrome
• Down’s syndrome
• Cystic fibrosis
• Primary biliary cholangitis
• Ovarian hyperstimulation
• Genetic

Question 9

What are the problems in pregnancy with hypothyroidism?

Answer 9

• Eclampsia
• Anaemia
• Prematurity
• Decreased birthweight
• Stillbirth
• Post partum bleeding

Question 10

How is hypothyroidism treated?

Answer 10

• Levothyroxine
  
  • Review dose at first 12 weeks
  • Check TSH yearly once normal
• Treat the patients symptoms not the blood level but try and keep TSH levels at >0.5mu/L
• Thyroxine’s half life is 7 days so wait 4 week before checking TSH to see if a dose change is right
• Small changes in serum free T4 have a logarithmic effect on TSH
• Enzyme inducers increase the metabolism of levothyroxine

Question 11

How does amiodarone cause both hyper and hypothyroidism?

Answer 11

• Amiodarone is high in iodine and is structurally like T4
• 2% of users will get significant thyroid problems from it
• Hypothyroidism can be caused by iodine excess
  
  • T4 is release is inhibited
• Hyperthyroidism may be caused by a destructive thyroiditis causing hormone release

Question 12

How are amiodarone induced thyroid problems treated?

Answer 12

• Glucocorticoids - when radioiodine uptake is undetectable
• Thyroidectomy may be needed is amiodarone cannot be discontinued
• Check TFTs every 6 months when on amiodarone
• Amiodarone has a half life of 80 days so problems may persist after withdrawal

Question 13

What is myxoedema coma?

Answer 13

• The ultimate hypothyroid state before death

Question 14

What is subclinical hypothyroidism?

What risks do they carry?

Answer 14

• When TSH is elevated but T3 and T4 are still in normal range
• There is a risk of progression to clinical hyopthyroidism
• The risk doubles when thyroid peroxidase antibodies are present
• The risk is also increased in men

Question 15

How is subclinical hypothyroidism managed?

Answer 15

• Confirm that raised TSH is persistent (recheck in 2-4 months)
• Recheck the history and if any non-specific symptoms are present such as depression then consider treating
• Treat if:
  
  • TSH >10mu/L
  • Positive for thyroid autoanitbodies
  • Past (treated) Grave’s
  • Other organ specific autoimmunity as they are more lielly to progree to clinical hypothyroidism, such as
    
    • Diabetes (type 1)
    • Myesthenia gravis
    • pernicious anaemia
    • vitiligo
  • If symptoms improve after 6 months, continue, if not then discontinue
• If patients do not fall into any of the above categories, then monitor TSH yearly

Question 16

What happens if subclinical hyporthyroidism is over-treated?

Answer 16

• Small risk of atrial fibrillation and osteoporosis

Question 17

What is subclincial hyperthyroidism?

Answer 17

• It is when TSH is low and T3 and T4 is normal
• Increased risk of AF and osteoporosis

Question 18

How is subclinical hypothyroidism managed?

Answer 18

• Confirm that suppressed TSH is persistent (recheck in 2-4 months)
• Check for non thyroid related causes :
  
  • Illness
  • Pregnancy
  • Pituitary or hypothalamic insufficiency (if T4 or T3 are at the lower end of the reference range)
  • use of tsh suppressing medication
    
    • Thyroxine
    • Steroids
• If TSH is <0.1, treat on an individual basis, especially if patient is:
  
  • Symptomatic
  • AF
  • Unexplained weight loss
  • Osteoporosis
  • Goitre
• Treatment options are:

1. Carbimazole
2. Propylthiouracil
3. Radioiodine therapy

• If no symptoms, recheck every 6 months