Hyperthyroidism is a form of thyrotoxicosis caused by excess thyroid hormones secreted by an overactive thyroid gland. It can be caused by endogenous issues like Graves' disease or toxic multinodular goiter affecting the thyroid gland itself, or secondary/central hyperthyroidism where the pituitary gland is affected. Symptoms include increased metabolism, nervousness, appetite and heart rate. Treatment focuses on controlling thyroid hormone levels through anti-thyroid drugs, radioactive iodine therapy or surgery to the thyroid gland.
2. Hyperthyroidism
๏ต Is a form of Thyrotoxicosis in which excess amounts of TH are secreted from the thyroid
gland. (over-activity of thyroid gland).
๏ต Term can be used interchangeably with Thyrotoxicosis.
๏ต Thyrotoxicosis is a hyper-metabolic state caused by elevated circulating levels of free T3 and
T4.
3. Causes of Hyperthyroidism:
๏ต Causes can be classified as:
๏ต Exogenous-e.g iatrogenic(mainly due to excessive intake of TH).
๏ต Endogenous โ1.)Primary Hyperthyroidism (problem in thyroid gland).
-Graveโs Disease, Toxic Multinodular Goiter, a Solitary Toxic Adenoma.
-2.)Central (Secondary) Hyperthyroidism (problem in pituitary gland).
-TSH-secreting pituitary adenoma.
Thyrotoxicosis not associated with Hyperthyroidism includes subacute thyroiditis, ectopic thyroid tissue, and
ingestion of excessive TH.
4. Clinical Features:
๏ต Clinical features are attributable to the metabolic effects of increased circulating levels of TH.
๏ต Increased BMR with heat intolerance & increased tissue sensitivity to stimulation by the Sympathetic Nervous System.
๏ต Enlargement of Thyroid gland(GOITER) is common in hyperthyroid conditions caused by stimulation of TSH receptors.
๏ต Nervous: Restlessness,LowAttention span, Fatigue,
๏ต Increased Appetite.
๏ต CVS: High CO,Low Peripheral resistance, Loud heart
sounds.
๏ต Sensory(Eyes): Elevated upper eyelid leading to
increased blinking & a staring quality.
๏ต
5. Evaluation:
T3 level T4 level TSH level
1. Primary Hyperthyroidism Increased Increased Decreased
2. Secondary Hyperthyroidism Increased Increased Increased
๏ Radioactive iodine is used to test for increased uptake in primary hyperthyroidism.
6. Treatment:
๏ต Directed at controlling excessive TH production, secretion, or action.
๏ต Major Therapy includes:
๏ต Anti-thyroid drug therapy (Methimazole & Propylthiouracil(PTU)-both have same mechanism)
๏ต Radioactive iodine therapy
๏ต Surgery (partial or complete).