Hypothyroidism Flashcards
What is hypothyroidism?
Hypothyroidism is a condition where the thyroid gland produces insufficient thyroid hormones, leading to a slowdown of metabolic processes.
What are the common symptoms of hypothyroidism?
Fatigue, weight gain, cold intolerance, dry skin, constipation, depression, and bradycardia.
What are the common causes of primary hypothyroidism?
Hashimoto’s thyroiditis, iodine deficiency, thyroidectomy, radioiodine therapy, and certain medications (e.g., amiodarone, lithium).
What is the most common cause of hypothyroidism in iodine-sufficient regions?
Hashimoto’s thyroiditis, an autoimmune condition.
What is the pathophysiology of Hashimoto’s thyroiditis?
Autoimmune destruction of the thyroid gland leads to reduced thyroid hormone production and eventual hypothyroidism.
What are the secondary causes of hypothyroidism?
Secondary hypothyroidism is caused by pituitary dysfunction resulting in reduced TSH production, often due to tumours, surgery, or trauma.
What are the clinical signs of hypothyroidism on examination?
Dry skin, bradycardia, facial puffiness, hoarseness, goitre, slow-relaxing reflexes, and hair thinning.
How does hypothyroidism affect metabolism?
Reduced thyroid hormone levels slow metabolic processes, leading to weight gain, cold intolerance, and fatigue.
What are the effects of hypothyroidism on the cardiovascular system?
Bradycardia, reduced cardiac output, and in severe cases, pericardial effusion or heart failure.
What are the effects of hypothyroidism on the gastrointestinal system?
Hypothyroidism causes reduced gut motility, leading to constipation.
What are the effects of hypothyroidism on the skin and hair?
Dry, coarse skin, brittle hair, and hair thinning, including lateral eyebrow loss.
What are the typical biochemical findings in primary hypothyroidism?
High TSH and low free T4 levels.
What are the typical biochemical findings in secondary hypothyroidism?
Low or inappropriately normal TSH and low free T4 levels.
What additional investigations can support the diagnosis of Hashimoto’s thyroiditis?
Testing for anti-thyroid peroxidase (TPO) antibodies, which are commonly elevated in Hashimoto’s thyroiditis.
What is subclinical hypothyroidism?
A condition characterised by elevated TSH with normal free T4 levels, often without symptoms.
What is the first-line treatment for hypothyroidism?
Levothyroxine, a synthetic form of T4, is the first-line treatment.
How is the dose of levothyroxine monitored?
By measuring TSH levels and adjusting the dose to maintain TSH within the reference range.
What is myxoedema?
Severe, untreated hypothyroidism presenting with symptoms such as hypothermia, bradycardia, confusion, and myxoedema coma in extreme cases.
How is myxoedema coma managed?
Intravenous levothyroxine, supportive care (e.g., warming, fluid resuscitation), and treatment of underlying triggers like infection.
What are the complications of untreated hypothyroidism?
Cardiovascular disease, infertility, myxoedema coma, and in pregnant women, adverse effects on foetal development.
How does hypothyroidism affect cholesterol levels?
Hypothyroidism can cause hypercholesterolaemia due to reduced lipid metabolism.
What are the risk factors for hypothyroidism?
Female sex, age over 60, family history of thyroid disease, autoimmune conditions, and iodine deficiency.
What is the role of iodine in thyroid function?
Iodine is essential for the synthesis of thyroid hormones T3 and T4.
What are the common differential diagnoses for hypothyroidism?
Depression, chronic fatigue syndrome, anaemia, and other causes of weight gain or fatigue.
What lifestyle advice should be given to patients with hypothyroidism?
Take levothyroxine on an empty stomach, monitor symptoms and TSH regularly, and maintain a balanced diet to avoid excessive iodine intake.
