Endocrinology Thyroid Function Quiz

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Questions and Answers

What hormone regulates thyroid hormone production, secretion, and growth?

TRH

TSH (correct)

Which clinical syndrome occurs when tissues are exposed to high levels of circulating thyroid hormones?

Cretinism

Thyrotoxicosis (correct)

Goitre

Hypothyroidism

Which of the following signs indicates a lagging upper eyelid when looking downwards?

Chvostek's sign

Joffroy's sign

Trousseau's sign

Von Graefe's sign (correct)

What is a common symptom associated with hyperthyroidism?

Rapid heart beat Signup and view all the answers

Which condition is characterized by an absence of wrinkling on the forehead when the patient looks upwards?

Joffroy's sign Signup and view all the answers

Which diagnostic measurement is essential for evaluating thyroid function?

Total T4 and Total T3 levels Signup and view all the answers

What is a common symptom of hypothyroidism?

Fatigue Signup and view all the answers

Which of the following statements is true regarding the regulation of TSH?

It is regulated by negative feedback from T4 and T3. Signup and view all the answers

Which of the following hormones is primarily secreted by the thyroid gland?

Thyroxine (T4) Signup and view all the answers

What is the primary source of circulating T3 in the body?

Deiodination of T4 Signup and view all the answers

Which plasma carrier protein binds the highest percentage of circulating T4?

Thyroxine-binding globulin (TBG) Signup and view all the answers

What is a normal range for radioactive iodine uptake 24 hours after administration?

5 - 30 % Signup and view all the answers

What percentage of total circulating T4 is considered free and has metabolic activity?

0.03% Signup and view all the answers

Which treatment is the most common cause of iatrogenic Cushing syndrome?

Steroid therapy Signup and view all the answers

What is the recommended minimum daily intake of iodine for proper thyroid function?

150 μg/day Signup and view all the answers

Which of the following actions is NOT a function of thyroid hormones?

Decreases serum glucose Signup and view all the answers

Which symptom is NOT typically associated with acromegaly?

Elevated blood pressure Signup and view all the answers

What aspect of growth hormone affects blood glucose levels?

Increases blood glucose Signup and view all the answers

How does T3 affect bone growth and development?

Regulates skeletal maturation at the growth plate Signup and view all the answers

What type of biopsy is often used to investigate thyroid nodules?

Fine needle aspiration biopsy Signup and view all the answers

What is the role of calcitonin, secreted by parafollicular cells of the thyroid gland?

Decrease blood calcium levels Signup and view all the answers

Which main factor distinguishes free hormones from total hormones in the context of thyroid hormone activity?

Only unbound hormones have metabolic activity Signup and view all the answers

Which of the following is a potential consequence of excess growth hormone secretion?

Prognathism Signup and view all the answers

What hormone is secreted by the adrenal cortex?

Cortisol Signup and view all the answers

What is the effect of thyroid hormones on the basal metabolic rate?

They increase metabolic rate Signup and view all the answers

What is a possible symptom of a pituitary tumor aside from hormonal effects?

Vision loss Signup and view all the answers

Which of the following is NOT a symptom associated with adrenal malignancy?

Diarrhea Signup and view all the answers

What condition results from an insufficient production of hormones from the adrenal glands?

Addison's Disease Signup and view all the answers

What is the primary stimulus for the secretion of parathyroid hormone (PTH)?

Hypocalcemia Signup and view all the answers

Which symptom is commonly associated with hypoparathyroidism?

Weakness Signup and view all the answers

Which of the following is a clinical sign of adrenal malignancy?

Stria rubra Signup and view all the answers

What might excessive secretion of parathormone lead to?

Constipation Signup and view all the answers

Which symptom is indicative of secondary adrenal insufficiency?

Fatigue or lethargy Signup and view all the answers

Which of the following conditions is NOT associated with the destruction of adrenal glands?

Obesity Signup and view all the answers

What is a consequence of calcium deposition in the renal tubules?

Increased susceptibility to renal stones Signup and view all the answers

Which of the following is a common clinical manifestation of hypercalcemia?

Emotional instability Signup and view all the answers

What is the typical cause of hypoparathyroidism following surgery?

Neck exploration Signup and view all the answers

Which diagnostic test would be least relevant for assessing hyperparathyroidism?

Serum potassium levels Signup and view all the answers

What condition is indicated by an increase in alkaline phosphatase?

Hypercalcemia Signup and view all the answers

Which feature is least likely to be associated with hypoparathyroidism?

Increased calcium levels Signup and view all the answers

Which symptom is associated with calcium calcification of the skin?

Severe pruritus Signup and view all the answers

What is a potential complication of untreated osteitis fibrosa cystica?

Bone resorption and brown tumors Signup and view all the answers

Study Notes

Thyroid Hormone Regulation

Thyroid-stimulating hormone (TSH) is responsible for regulating thyroid hormone production, secretion, and growth.

Thyroid Hormone Excess

Thyrotoxicosis occurs when tissues are exposed to high levels of circulating thyroid hormones.

Signs of Hyperthyroidism

Lagging upper eyelid when looking downwards is known as Dalrymple's sign.
Hyperthyroidism often leads to increased appetite despite weight loss.
Absence of wrinkling on the forehead when looking upwards is called Möbius sign.
Thyroid function tests, specifically TSH and free T4 levels, are vital for evaluating thyroid function.

Hypothyroidism and TSH Regulation

Hypothyroidism is characterized by slowed metabolism, often leading to fatigue and weight gain.
TSH secretion is regulated by negative feedback, meaning high levels of thyroid hormones inhibit further TSH release.

Thyroid Hormone Characteristics and Production

T4 (thyroxine) is the primary hormone secreted by the thyroid gland.
Peripheral conversion of T4 to T3 is the primary source of circulating T3 in the body.
Thyroid-binding globulin (TBG) is the main plasma carrier protein for T4 in the circulation.

Iodine and Thyroid Function

Radioactive iodine uptake is measured 24 hours after administration to evaluate thyroid function with a normal range of 15-30%.
Free T4 constitutes 0.03-0.05% of total circulating T4 and is metabolically active.
Iodine deficiency can significantly impair thyroid function, and the recommended daily intake is 150-200 microg.

Growth Hormone and Acromegaly

Growth hormone excess, resulting in acromegaly, leads to enlargement of hands, feet, and facial features.
Growth hormone affects blood glucose levels by promoting insulin resistance.

Thyroid Effects on Bone

T3 plays a crucial role in normal bone growth and development.

Thyroid Nodule Evaluation

Fine-needle aspiration biopsy is a commonly used procedure to investigate thyroid nodules.

Calcitonin and Hormone Regulation

Calcitonin, secreted by parafollicular cells of the thyroid gland, helps regulate calcium levels in the blood.
Free hormones are the biologically active form of hormones, unlike total hormones that include both bound and unbound forms.

Excess Growth Hormone Effects

Excess growth hormone secretion can lead to gigantism in children and acromegaly in adults.

Adrenal Cortex and Hormones

Cortisol is the primary hormone secreted by the adrenal cortex.

Thyroid Hormone and Metabolism

Thyroid hormones increase basal metabolic rate, influencing energy expenditure and body temperature regulation.

Pituitary Tumor and Adrenal Malignancy

Pituitary tumors can cause visual disturbances in addition to hormonal imbalances.
Adrenal malignancy is characterized by abdominal pain, weight loss, and darkening of the skin (hyperpigmentation), among other symptoms.

Adrenal Insufficiency and Parathyroid Hormone

Addison's disease is a condition caused by insufficient production of hormones from the adrenal glands, leading to fatigue, weakness, and low blood pressure.
Low blood calcium levels are the primary stimulus for the secretion of parathyroid hormone (PTH).

Hypoparathyroidism and Hyperparathyroidism

Muscle spasms and seizures are common symptoms of hypoparathyroidism.
Adrenal malignancy can manifest with hypertension, hypokalemia, and hyperglycemia.
Excessive secretion of parathormone can lead to osteitis fibrosa cystica, a condition causing bone loss and fractures.

Secondary Adrenal Insufficiency and Adrenal Gland Destruction

Secondary adrenal insufficiency usually arises from pituitary gland dysfunction, leading to fatigue, weakness, and low blood pressure.
Adrenal gland destruction can occur due to autoimmune diseases, infections, or surgical removal.

Kidney and Calcium Deposition

Calcium deposition in renal tubules can lead to kidney stones and renal failure.

Hypercalcemia and Hypoparathyroidism

Hypercalcemia can manifest as constipation, confusion, and weakness.
Hypoparathyroidism after surgery commonly stems from damage to the parathyroid glands during the procedure.

Diagnostic Tests for Parathyroid Disorders

Alkaline phosphatase levels are not directly relevant for assessing hyperparathyroidism, but they can indicate bone disease associated with it.

Hypoparathyroidism and Osteitis Fibrosa Cystica

Hypoparathyroidism` is not characterized by brittle bones, but rather by decreased bone formation and increased bone resorption.
Calcium calcification of the skin is a rare condition associated with hypercalcemia and can manifest as cutaneous calcinosis.
Osteitis fibrosa cystica, if left untreated, can potentially lead to fractures, bone deformities, and kidney stones.

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Description

Test your knowledge on thyroid function, including hormone regulation and associated clinical syndromes. This quiz covers symptoms, diagnostic measurements, and the key hormones involved in thyroid health. Perfect for students of endocrinology and medical professionals alike.