HYPOTHYROIDISM Flashcards
(100 cards)
What is hypothyroidism?
Hypothyroidism results from any disorder that leads to insufficient secretion of thyroid hormones from the thyroid gland.
Name the four causes of congenital hypothyroidism.
- Absent or under-developed thyroid gland<br></br>2. Dyshormogenesis - genetic defects in the synthesis of thyroid hormones, resulting in hypothyroidism with goitre<br></br>3. Iodine deficiency during pregnancy<br></br>4. Maternal transmission of antithyroid drugs
List three causes of primary hypothyroidism.
- Hashimoto’s thyroiditis<br></br>2. Iodine deficiency<br></br>3. Iatrogenic causes (e.g., post-ablative therapy, surgery)
What are the clinical features related to decreased metabolic rate in hypothyroidism?
Tiredness/malaise, weight gain, cold intolerance, decreased sweating, coarse, sparse hair, brittle nails, cold, dry skin, constipation, bradycardia, hypothyroid myopathy, delayed relaxation of deep tendon reflexes, hyperlipidemia (xanthelasmas), hypercarotenemia.
Define myxoedema and list symptoms related to generalised myxoedema in hypothyroidism.
Myxoedema refers to the accumulation of mucopolysaccharide in subcutaneous tissues. Symptoms include doughy skin texture, puffy appearance, myxoedematous heart disease, periorbital edema, pretibial myxoedema, entrapment syndromes, peripheral neuropathy, macroglossia, deep hoarse voice, myxoedema coma.
What is the most common cause of hypothyroidism in iodine-sufficient regions?
Hashimoto’s thyroiditis.
Name the thyroid antibodies associated with autoimmune hypothyroidism.
Anti-TPO antibody (95%), Anti-thyroglobulin (60%), TSH receptor antibody (blocking) (10-20%).
How is myxoedema coma managed?
Passively rewarm, cardiac monitoring for arrhythmias, close monitoring of urine output, fluid balance, central venous pressure, blood sugars, oxygenation, broad-spectrum antibiotics, thyroxine cautiously, hydrocortisone if adrenal failure.
What are the long-term complications of autoimmune hypothyroidism?
Increased risk of developing other autoimmune diseases and increased risk of developing B-cell NHL in the affected gland.
How is levothyroxine dosage adjusted in elderly patients with a history of ischemic heart disease?
Start levothyroxine at 25-50 µg daily and adjust every 4 weeks according to response.
In secondary hypothyroidism, what are the levels of TSH, Free T4, and T3?
TSH is low (or ‘normal’), and Free T4 and T3 are low.
Name three symptoms related to decreased metabolic rate in hypothyroidism.
- Tiredness/malaise<br></br>2. Weight gain, despite decreased appetite<br></br>3. Cold intolerance
What are the dermatological symptoms associated with hypothyroidism?
Coarse, sparse hair, brittle nails, cold, dry skin
What gastrointestinal symptoms are commonly seen in hypothyroidism?
Constipation
Describe the cardiovascular symptom associated with hypothyroidism.
Bradycardia - slow pulse
What is hypothyroid myopathy, and what are its symptoms?
Hypothyroid myopathy is characterized by myalgia, stiffness, and cramps.
What is the significance of delayed relaxation of deep tendon reflexes in hypothyroidism?
It is a neurological symptom associated with hypothyroidism.
Name the lipid-related symptom seen in hypothyroidism.
Hyperlipidemia - xanthelasma
What is hypercarotenemia, and how is it related to hypothyroidism?
Hypercarotenemia is the presence of high levels of carotene in the blood. It is related to hypothyroidism and is associated with a yellowish discoloration of the skin.
Define myxoedema and list symptoms related to generalised myxoedema in hypothyroidism.
Myxoedema refers to the accumulation of mucopolysaccharide in subcutaneous tissues. Symptoms include doughy skin texture, puffy appearance, myxoedematous heart disease, periorbital edema, pretibial myxoedema, entrapment syndromes, peripheral neuropathy, macroglossia, deep hoarse voice, myxoedema coma.
What symptoms are associated with myxoedematous heart disease?
Dilated cardiomyopathy, bradycardia, dyspnea, pericardial effusion, worsening of heart failure
What is the significance of periorbital edema in hypothyroidism?
Periorbital edema is a symptom of hypothyroidism, distinguishing it from hyperthyroidism.
Name symptoms related to hyperprolactinemia in hypothyroidism.
Menorrhagia, later oligo or amenorrhea
What are the additional symptoms associated with hypothyroidism?
Goiter (in Hashimoto thyroiditis) or atrophic thyroid (in atrophic thyroiditis), impaired cognition, depression, vitiligo, obstructive sleep apnea.
2. ↑ Creatinine kinase
3. ↑ LDL cholesterol
4. Hyponatremia (due to ↓ renal tubular water loss)
5. Hyperprolactinemia
2. Anti-thyroglobulin - 60%
3. TSH receptor antibody (blocking) - 10-20%
2. ABGs (Arterial Blood Gases): Type 2 respiratory failure (hypoxia, hypercarbia, respiratory acidosis).
2. Increased risk of developing B-cell non-Hodgkin lymphoma (NHL) in the affected gland.