Endocrinology Practice Questions

Q: ACTH reserve is best assessed by which test?

Insulin-induced hypoglycemia. ***Insulin-induced hypoglycemia*** - This test is considered the **gold standard** for assessing ACTH reserve because the resulting **severe stress** is the most potent physiological stimulus for both ACTH and growth hormone secretion [1]. - A healthy pituitary gland will respond to the stress of hypoglycemia by significantly increasing ACTH and cortisol levels; a blunted response indicates **adrenal insufficiency** or **pituitary dysfunction** [1]. *Corticotropin-releasing hormone (CRH) test* - The CRH test assesses the **pituitary's response to CRH** in releasing ACTH, helping to distinguish between primary and secondary adrenal insufficiency. - While it evaluates ACTH secretion, it does not assess the overall functional reserve of the HPA axis to a strong physiological stressor as effectively as insulin-induced hypoglycemia. *ACTH stimulation test* - The ACTH stimulation test, or **cosyntropin stimulation test**, directly evaluates the **adrenal gland's capacity to produce cortisol** in response to exogenous ACTH [2]. - This test assesses primary adrenal insufficiency, but it does not evaluate the **pituitary gland's ability to release ACTH** (ACTH reserve) [2]. *Glucocorticoid levels assessment* - Measuring baseline glucocorticoid (cortisol) levels provides a snapshot of adrenal function at a single point in time, but it does not assess the **reserve or responsiveness of the HPA axis** to stress [1]. - For a more accurate assessment, these levels need to be interpreted in the context of diurnal variation or dynamic testing [1].

Q: Which antibodies are primarily associated with Graves' disease?

TSH receptor antibodies (TRAb). ***TSH receptor antibodies (TRAb)*** - **TRAb** directly stimulate the **TSH receptor** on thyroid follicular cells, leading to excessive thyroid hormone production and the characteristic features of **Graves' disease** [1], [2]. - These antibodies are highly specific for Graves' disease and are used for diagnosis, management, and prediction of remission [1]. *Antinuclear antibodies (ANA)* - **ANA** are associated with various **systemic autoimmune diseases** like lupus and scleroderma, not primarily with Graves' disease. - While ANA can be positive in a small percentage of Graves' patients due to general immune dysregulation, they are not the causative or primary diagnostic antibody. *Thyroid peroxidase antibodies (TPO)* - **TPO antibodies** are primarily associated with **Hashimoto's thyroiditis**, causing thyroid destruction and hypothyroidism. - Although they can be present in Graves' disease, they are not the main pathogenic antibodies responsible for hyperthyroidism. *Anti-thyroglobulin antibodies* - **Anti-thyroglobulin antibodies** are also mainly associated with **Hashimoto's thyroiditis** and other autoimmune thyroid conditions. - They target thyroglobulin, a precursor to thyroid hormones, but do not directly stimulate thyroid hormone synthesis as TRAb do in Graves' disease.

Q: Which assay is primarily used to assess growth hormone levels?

Growth hormone stimulation test. ***Growth hormone stimulation test*** - This is the primary diagnostic assay to evaluate **growth hormone (GH) deficiency** or excess, as GH levels fluctuate throughout the day. - Various stimuli, such as **insulin-induced hypoglycemia**, **arginine**, or **clonidine**, are used to trigger GH release, and levels are measured serially [1]. *Diabetes mellitus* - This is a metabolic disorder characterized by **elevated blood glucose levels** due to insulin deficiency or resistance, not an assay for growth hormone. - While growth hormone can affect glucose metabolism, diabetes mellitus describes a **disease state**, not a diagnostic test for growth hormone levels [2]. *Glucagon assay* - A glucagon assay measures the level of **glucagon**, a hormone produced by the pancreas that raises blood glucose levels. - While glucagon can be used in some stimulation tests for growth hormone, a "glucagon assay" alone is not the primary method to assess overall growth hormone status. *Catecholamines* - Catecholamines are a group of hormones, including **epinephrine (adrenaline)**, **norepinephrine**, and **dopamine**, which are involved in the body's stress response. - Assays for catecholamines are used to diagnose conditions like **pheochromocytoma** or neuroblastoma, not to assess growth hormone levels.

Q: A woman with two children presents with galactorrhea and amenorrhea for one year. The most probable diagnosis is:

Prolactinoma. ***Prolactinoma*** - The classic presentation of **galactorrhea** (milk production unrelated to pregnancy or breastfeeding) and **amenorrhea** (absence of menstruation) in a non-pregnant woman strongly suggests hyperprolactinemia, most commonly due to a **prolactin-secreting pituitary adenoma** (prolactinoma). - High prolactin levels can inhibit GnRH pulsatility from the hypothalamus, leading to decreased LH and FSH secretion, which in turn causes **anovulation** and thus amenorrhea. *Ectopic pregnancy* - This condition presents with symptoms like **abdominal pain**, vaginal bleeding, and a **positive pregnancy test**, which are not mentioned here. - While an ectopic pregnancy is a cause of amenorrhea, it does not typically cause galactorrhea. *Pituitary apoplexy* - This is an acute, life-threatening condition caused by hemorrhage or infarction of the pituitary gland, presenting with **sudden severe headache**, visual disturbances, and altered mental status. - While it can affect pituitary function, its acute onset and severe symptoms are inconsistent with the one-year history of galactorrhea and amenorrhea. *Hypothalamic dysfunction* - Although hypothalamic dysfunction can cause amenorrhea due to impaired GnRH release, it typically presents with **low or normal prolactin levels**, not elevated prolactin causing galactorrhea. - Conditions like **functional hypothalamic amenorrhea** (due to stress, excessive exercise, or low body weight) would involve a different hormonal profile.

Q: Malignancy-associated hypercalcemia is due to?

Parathyroid hormone-related peptide (PTHrP). Malignancy-associated hypercalcemia is primarily due to **parathyroid hormone-related peptide (PTHrP)**, which mimics the action of parathyroid hormone, causing increased calcium release from bones [1][2]. This condition is often seen in **solid tumors**, particularly squamous cell carcinomas, and can lead to significant **hypercalcemia** [2][3]. *Tumor lysis syndrome* - Tumor lysis syndrome results from rapid cell lysis leading to **release of intracellular contents**, causing hyperuricemia, not directly hypercalcemia. - It is characterized by **electrolyte imbalances** such as hyperkalemia, hyperphosphatemia, but not primarily hypercalcemia. *IGF-b* - Insulin-like Growth Factor (IGF) is primarily involved in **growth processes** and does not lead to hypercalcemia. - While it has an association with cancer, it does not function in the pathway that elevates serum calcium levels. *IL-7* - Interleukin-7 (IL-7) is mainly related to **T-cell development** and does not play a role in hypercalcemia associated with malignancy. - While cytokines can influence various pathways in cancer, IL-7 is not implicated in **calcium metabolism**.

Q: Which of the following statements about factitious thyrotoxicosis is true?

Radionuclide uptake is low.. ***Radionuclide uptake is low.*** - In **factitious thyrotoxicosis**, the exogenous thyroid hormone suppresses the thyroid gland, leading to very low or absent **radionuclide uptake** on a scan [1]. - This differentiates it from other causes of thyrotoxicosis, like **Graves' disease** or **toxic multinodular goiter**, which show high uptake [1]. *It can be seen in healthcare professionals.* - While factitious thyrotoxicosis can occur in anyone, it is not uniquely or predominantly seen in **healthcare professionals**. - The behavior is linked to **deception** regarding illness or medication use, not profession. *TSH levels are typically elevated.* - In factitious thyrotoxicosis, the **exogenous thyroid hormone** suppresses endogenous thyroid stimulating hormone (TSH) production [1]. - Therefore, **TSH levels are typically suppressed or undetectable**, indicating the thyroid gland is not being stimulated to produce excess hormones. *It presents with features typical of thyrotoxicosis.* - While patients with factitious thyrotoxicosis may have symptoms of **thyrotoxicosis** due to excess thyroid hormone, the term refers to the *cause* being external (self-administered hormone) [1]. - The disease refers to the *self-administration* of thyroid hormones, which then leads to the symptoms [1].

Q: What would be the most probable diagnosis for a 50-year-old chronic smoker who presents with hemoptysis, truncal obesity, and hypertension, and has an elevated ACTH level that is not suppressible with high-dose dexamethasone?

Ectopic ACTH producing lung cancer. ***Ectopic ACTH producing lung cancer*** - The combination of **hemoptysis** in a **chronic smoker** points towards a pulmonary malignancy, which can produce **ectopic ACTH**, leading to Cushing's syndrome symptoms [2, 5]. - The **elevated ACTH** that is **not suppressible with high-dose dexamethasone** is characteristic of ectopic ACTH production, as the tumor cells do not respond to feedback inhibition [1]. *Adrenal adenoma* - An **adrenal adenoma** causes **ACTH-independent Cushing's syndrome**, meaning ACTH levels would be low [1]. - While it can cause symptoms like truncal obesity and hypertension, it does not explain the hemoptysis or elevated ACTH. *Bilateral adrenal hyperplasia* - **Bilateral adrenal hyperplasia** can cause Cushing's syndrome, but it is typically **ACTH-dependent** and often responsive to high-dose dexamethasone if it's pituitary-driven [1]. - It does not account for the hemoptysis or the **non-suppressible ACTH** level in this particular presentation. *Pituitary tumor* - A **pituitary tumor** (Cushing's disease) produces ACTH, causing Cushing's syndrome, and typically shows **suppression with high-dose dexamethasone** (though not always fully). - It would not explain the symptom of **hemoptysis** associated with a chronic smoker [2].

Q: What is the most common cause of hypercalcemic crisis?

Parathyroid adenoma. ***Parathyroid adenoma*** - **Primary hyperparathyroidism**, most often caused by a solitary parathyroid adenoma, is the leading cause of hypercalcemic crisis, though this is rare [1][2]. - The adenoma autonomously overproduces **parathyroid hormone (PTH)**, leading to increased calcium reabsorption from bone and kidneys, and enhanced intestinal calcium absorption [1]. *Carcinoma of the breast* - While breast carcinoma can lead to **hypercalcemia** through bony metastases or parathyroid hormone-related peptide (PTHrP) production, it's not the most common cause of hypercalcemic crisis. - Metastatic bone disease is a common cause of hypercalcemia in malignancy, but the extent of hypercalcemia varies. *Parathyroid hyperplasia* - **Parathyroid hyperplasia** is a rarer cause of primary hyperparathyroidism compared to adenoma, and thus less frequently causes hypercalcemic crisis [2]. - All four parathyroid glands are typically enlarged and overactive, leading to excessive PTH secretion. *Paget's disease* - **Paget's disease of bone** primarily causes localized areas of increased bone turnover and can lead to elevated **alkaline phosphatase** levels. - It rarely causes significant hypercalcemia, and even more rarely a hypercalcemic crisis, unless there is prolonged immobilization or coexisting hyperparathyroidism.

Q: All are seen in pheochromocytoma except which of the following?

Hypotension. ***Hypotension*** - Pheochromocytoma is characterized by the **overproduction of catecholamines** (epinephrine and norepinephrine), which typically cause **hypertension** rather than hypotension. - The classic symptoms of pheochromocytoma, often described as the "5 Ps," are **pain (headache)**, **palpitations**, **perspiration**, **pallor**, and **paroxysmal hypertension**. *Headaches* - **Severe, throbbing headaches** are a very common symptom in pheochromocytoma due to the **vasospastic effects** of high circulating catecholamines. - These headaches are often sudden in onset and can be debilitating. *Weight loss* - The **hypermetabolic state** induced by excessive catecholamines can lead to **increased caloric expenditure** and subsequently, **weight loss**. - Catecholamines increase **basal metabolic rate** and breakdown of fat stores. *Sweating attacks* - **Diaphoresis** or profuse sweating attacks are a hallmark symptom, caused by **sympathetic nervous system activation** due to high catecholamine levels. - These attacks are often paroxysmal and can be accompanied by an exacerbation of other symptoms.

Q: Riedel's thyroiditis is associated with which of the following conditions?

Retroperitoneal fibrosis. ***Retroperitoneal fibrosis*** - **Riedel's thyroiditis** is a rare, chronic inflammatory condition characterized by the replacement of normal thyroid tissue with dense **fibrous tissue**. - It is often associated with other **fibrosing conditions**, including **retroperitoneal fibrosis**, sclerosing cholangitis, and orbital pseudotumor. *Hyperthyroidism* - **Riedel's thyroiditis** typically leads to **hypothyroidism** or euthyroidism, as the extensive fibrosis destroys thyroid tissue. - Hyperthyroidism is more commonly seen in conditions like **Graves' disease** or toxic nodular goiter. *Hyperparathyroidism* - **Hyperparathyroidism** is a disorder of the parathyroid glands leading to elevated calcium levels, and there is no direct association with **Riedel's thyroiditis**. - Riedel's thyroiditis primarily affects the thyroid gland and its surrounding structures. *Non-palpable thyroid gland* - **Riedel's thyroiditis** typically presents as a **hard, fixed, and often asymmetrical goiter** that can be easily palpated. - The fibrosis makes the gland very firm and usually causes local compressive symptoms.

Question 1

ACTH reserve is best assessed by which test?

Accepted Answer

Insulin-induced hypoglycemia

Answer

Corticotropin-releasing hormone (CRH) test

Answer

ACTH stimulation test

Answer

Glucocorticoid levels assessment

Question 2

Which antibodies are primarily associated with Graves' disease?

Accepted Answer

TSH receptor antibodies (TRAb)

Answer

Antinuclear antibodies (ANA)

Answer

Thyroid peroxidase antibodies (TPO)

Answer

Anti-thyroglobulin antibodies

Question 3

Which assay is primarily used to assess growth hormone levels?

Accepted Answer

Growth hormone stimulation test

Answer

Diabetes mellitus

Answer

Glucagon assay

Answer

Catecholamines

Question 4

A woman with two children presents with galactorrhea and amenorrhea for one year. The most probable diagnosis is:

Accepted Answer

Prolactinoma

Answer

Ectopic pregnancy

Answer

Pituitary apoplexy

Answer

Hypothalamic dysfunction

Question 5

Malignancy-associated hypercalcemia is due to?

Accepted Answer

Parathyroid hormone-related peptide (PTHrP)

Answer

Vitamin D secretion by tumors

Answer

Cytokine-mediated osteoclast activation

Answer

Bone metastases causing osteolysis

Question 6

Which of the following statements about factitious thyrotoxicosis is true?

Accepted Answer

Radionuclide uptake is low.

Answer

TSH levels are typically elevated.

Answer

It can be seen in healthcare professionals.

Answer

It presents with features typical of thyrotoxicosis.

Question 7

What would be the most probable diagnosis for a 50-year-old chronic smoker who presents with hemoptysis, truncal obesity, and hypertension, and has an elevated ACTH level that is not suppressible with high-dose dexamethasone?

Accepted Answer

Ectopic ACTH producing lung cancer

Answer

Adrenal adenoma

Answer

Bilateral adrenal hyperplasia

Answer

Pituitary tumor

Question 8

What is the most common cause of hypercalcemic crisis?

Accepted Answer

Parathyroid adenoma

Answer

Carcinoma of the breast

Answer

Parathyroid hyperplasia

Answer

Paget's disease

Question 9

All are seen in pheochromocytoma except which of the following?

Accepted Answer

Hypotension

Answer

Headaches

Answer

Weight loss

Answer

Sweating attacks

Question 10

Riedel's thyroiditis is associated with which of the following conditions?

Accepted Answer

Retroperitoneal fibrosis

Answer

Hyperthyroidism

Answer

Hyperparathyroidism

Answer

Non-palpable thyroid gland

Endocrinology — MCQs

Endocrinology — MCQs

On this page

Practice by Chapter

Want unlimited practice?