THYROID DISORDERS 1.3 (based on T) Flashcards
What is goiter?
Any enlargement (either diffuse or nodular) of the thyroid gland regardless of function.
What are common causes of goiter?
Iodine deficiency, Graves’ disease, goitrous Hashimoto’s thyroiditis.
How does iodine deficiency cause goiter?
Reduced efficiency of thyroid hormone synthesis → high TSH → goiter (low functioning goiter).
How does Graves’ disease cause goiter?
TSH-R-mediated effects of thyroid-stimulating immunoglobulin.
How does Hashimoto’s thyroiditis cause goiter?
Acquired defects in hormone synthesis → high TSH → goiter, along with lymphocytic infiltration and immune-induced growth factors.
What are the classifications of goiter?
Diffuse (toxic or non-toxic) and nodular (solitary or multinodular, toxic or non-toxic).
What is diffuse nontoxic (simple) goiter also called?
Colloid goiter.
What are the characteristics of diffuse nontoxic goiter?
Diffuse thyroid enlargement without nodules and hyperthyroidism, more common in women.
What is the most common cause of diffuse nontoxic goiter?
Iodine deficiency.
What are the types of diffuse nontoxic goiter based on etiology?
Sporadic goiter (unknown cause, non-endemic regions), juvenile goiter (teenagers), endemic goiter (>5% of population affected, environmental goitrogens).
What are examples of environmental goitrogens?
Thiocyanate, cruciferous vegetables (broccoli, cauliflower) in large amounts.
What are the clinical manifestations of diffuse nontoxic goiter?
Mostly asymptomatic, symmetrically enlarged, nontender, soft thyroid without nodules, can cause compression (tracheal/esophageal).
What is Pemberton’s sign?
Facial/neck congestion due to jugular venous obstruction when raising the arms above the head, seen in large goiters.
What lab findings are seen in diffuse nontoxic goiter?
TSH, T3, T4 may be normal; low urinary iodine (<50 g/L) in iodine deficiency.
What is the management of diffuse nontoxic goiter?
Iodine replacement (if iodine deficiency), subtotal or near-total thyroidectomy if compressing structures or for cosmetic reasons.
What is the definition of multinodular goiter (MNG)?
Presence of multiple nodules within the thyroid gland.
What is the prevalence of MNG?
Occurs in up to 12% of adults, more common in women, increases with age.
What are causes of MNG?
Genetic, autoimmune, and environmental influences.
What is the histologic appearance of MNG?
Wide variation in nodule size, hyperplastic regions, cystic areas, fibrosis, hemorrhage, and lymphocytic infiltration.
What are the clinical features of non-toxic MNG?
Asymptomatic euthyroid state, may be detected incidentally on physical exam or ultrasound.
What are possible complications of MNG?
Compressive symptoms (dysphagia, respiratory distress, plethora), sudden pain (hemorrhage into a nodule), hoarseness (laryngeal nerve involvement).
What diagnostic tests are used for MNG?
TSH levels, CT/MRI (for substernal extension or tracheal narrowing), barium swallow (esophageal compression), ultrasound (TIRADS classification), biopsy (for suspicious nodules).
What is the management of non-toxic MNG?
Conservative management (if asymptomatic), surgery (if obstructive or cosmetic reasons), radioiodine therapy in select cases.
What is toxic multinodular goiter (TMNG)?
Multinodular goiter with functional autonomy, leading to hyperthyroidism.
