Endocrinology Practice Questions

Q: What is the most common cause of hypothyroidism in pregnancy?

Autoimmune thyroiditis. ***Autoimmune thyroiditis*** - **Hashimoto's thyroiditis** is the most common autoimmune cause of hypothyroidism, and it is also the leading cause of hypothyroidism in pregnant women. - This condition involves the immune system attacking the thyroid gland, leading to reduced production of **thyroid hormones**. *Nutritional* - **Iodine deficiency** is a nutritional cause of hypothyroidism, but it is less common in areas with adequate iodine intake and fortification programs. - While iodine is crucial for thyroid hormone synthesis, **autoimmune destruction** of the thyroid gland is generally a more prevalent cause of deficiency in pregnant women in developed countries. *Irradiation* - Hypothyroidism due to **radiation exposure** to the neck is a potential cause, but it is typically linked to prior therapeutic interventions for cancers. - This is not a common cause of hypothyroidism in the general pregnant population unless there's a history of such treatment. *Anti thyroid drugs ie iatrogenic* - **Antithyroid drugs** are used to treat hyperthyroidism and can indeed cause iatrogenic (treatment-induced) hypothyroidism. - However, this would only be relevant in pregnant women who were being treated for hyperthyroidism, and it is not the most common underlying cause of a de novo presentation of hypothyroidism during pregnancy.

Q: What is the best screening test for pheochromocytoma?

Urinary metanephrine. ***Urinary metanephrine*** - **Urinary fractionated metanephrines** (metanephrine and normetanephrine) are catabolites of catecholamines and are now considered the most sensitive and specific screening test for **pheochromocytoma**. - The test involves collecting a **24-hour urine sample** to measure their levels, as their excretion is more constant than that of parent catecholamines. *Urinary VMA estimation* - **Vanillylmandelic acid (VMA)** is a metabolite of catecholamines, but its measurement in urine is generally **less sensitive** and specific than metanephrine measurement for screening pheochromocytoma. - While it can be elevated in pheochromocytoma, there are **more accurate and reliable tests** available. *Serum catecholamine estimation* - **Plasma free metanephrines** are often considered the most sensitive test, but measurement of **serum (or plasma) catecholamines** (epinephrine, norepinephrine, dopamine) can be highly variable due to their pulsatile release and short half-lives. - Levels can be significantly affected by **stress, exercise, and diet**, leading to false positives or negatives, making it less reliable for initial screening than metanephrines. *Clonidine suppression test* - The **clonidine suppression test** is a **confirmatory test**, not a screening test, used when there is biochemical evidence suggestive of pheochromocytoma, but the diagnosis is unclear [1]. - It helps differentiate between essential hypertension with elevated catecholamines and hypertension caused by pheochromocytoma, as clonidine suppresses neurogenically mediated catecholamine release but not release from a tumor [1].

Q: A 24-year-old accountant complains of a white discharge from his breasts. He is most likely experiencing which one of the following conditions?

A prolactinoma. ***A prolactinoma*** - A **prolactinoma** is a benign tumor of the pituitary gland that secretes **prolactin**, leading to **galactorrhea** (white discharge from the breasts) in both men and women. - In men, high prolactin levels can also cause **hypogonadism**, resulting in **decreased libido** and **erectile dysfunction**. *A tumor of the posterior pituitary that could be surgically removed* - The **posterior pituitary** primarily secretes **oxytocin** and **ADH** (antidiuretic hormone), not prolactin. Tumors here would likely present with symptoms related to these hormones, such as **diabetes insipidus**. - While pituitary tumors can be surgically removed, a **posterior pituitary tumor** is not the typical cause of galactorrhea. *Excessive production of OT in the hypothalamus* - **Oxytocin (OT)** is primarily involved in uterine contractions and milk ejection during lactation, not in milk production or spontaneous galactorrhea. - Excessive OT production would not cause a white discharge from the breasts in a non-lactating individual and is not typically associated with pituitary tumors. *Deficient testosterone receptors in the mammary glands* - **Testosterone receptors** are not directly involved in the production of milk or glandular discharge in mammary tissue. - While hormonal imbalances can affect breast tissue, a deficiency in testosterone receptors would not autonomously cause galactorrhea.

Q: Hirsutism is seen in all except:

Hypothyroidism. Hypothyroidism - Hypothyroidism is a state of insufficient thyroid hormone production, which typically leads to dry skin, brittle hair, and hair loss (alopecia), not hirsutism [1]. - Hirsutism is characterized by excessive male-pattern hair growth in women, which is primarily driven by elevated androgens, a hormonal imbalance not directly caused by hypothyroidism. Acromegaly - Acromegaly is a hormonal disorder resulting from excessive growth hormone (GH) and insulin-like growth factor 1 (IGF-1) production, primarily from a pituitary tumor. - Patients with acromegaly may experience hirsutism due to increased IGF-1 stimulating androgen production and increased sensitivity of hair follicles to androgens. Arrhenoblastoma - An arrhenoblastoma is a rare ovarian tumor that produces androgens (male hormones). - The elevated androgen levels lead to virilization, a common feature of which is hirsutism, along with clitoromegaly and voice deepening [2]. PCOD - Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by hormonal imbalances, including elevated androgen levels [2]. - Hirsutism is one of the primary diagnostic criteria and a frequent complaint in women with PCOS, driven by the increased androgen production from the ovaries and adrenal glands [2].

Q: VIPoma is associated with which syndrome?

Verner-Morrison syndrome. ***Verner-Morrison syndrome*** - **VIPoma** is a neuroendocrine tumor that secretes **vasoactive intestinal peptide (VIP)**, causing symptoms like watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome) [1]. - This clinical presentation is also known as **Verner-Morrison syndrome**, directly linking the VIPoma to this syndrome [1]. *Cushing's syndrome* - Characterized by excessive **cortisol** production, leading to symptoms like central obesity, moon facies, and hypertension [3]. - This syndrome is not directly associated with VIP excess or the watery diarrhea seen in VIPoma [2]. *Carcinoid syndrome (serotonin syndrome)* - Caused by tumors, typically in the gastrointestinal tract, that produce **serotonin**, leading to flushing, diarrhea, and bronchospasm [1]. - While it involves diarrhea, the primary mediator is serotonin, not VIP, and the other classic VIPoma symptoms (hypokalemia, achlorhydria) are absent [1]. *Zollinger-Ellison syndrome* - Characterized by a **gastrin-producing tumor (gastrinoma)**, which causes excessive gastric acid secretion and severe peptic ulcer disease [4]. - The hormonal excess is **gastrin**, not VIP, and symptoms are related to acid overproduction rather than massive watery diarrhea and hypokalemia [4].

Q: All of the following are seen in MEN 2B except which of the following?

Hyperparathyroidism. ***Hyperparathyroidism*** - **Hyperparathyroidism** is a characteristic feature of **MEN 1** and **MEN 2A**, but it is typically **absent in MEN 2B**. - MEN 2B is primarily associated with **RET gene mutations** that do not commonly lead to parathyroid gland hyperplasia or adenomas. *Neuromas* - **Mucosal neuromas**, particularly in the lips, tongue, and gastrointestinal tract, are a **hallmark feature of MEN 2B**. - These benign tumors are a key diagnostic clue for this syndrome. *Medullary carcinoma thyroid* - **Medullary thyroid carcinoma (MTC)** is a **nearly universal and aggressive component of MEN 2B**, arising from parafollicular C-cells. - It is often the presenting feature and requires early detection and thyroidectomy due to its high metastatic potential. *Pheochromocytoma* - **Pheochromocytoma**, a tumor of the adrenal medulla, occurs in approximately 50-70% of individuals with **MEN 2B**. - It can cause severe hypertension and is an important component of the syndrome that needs to be screened for due to its potential for life-threatening hypertensive crises.

Q: Foot ulcers in diabetes are due to all except which of the following?

Hypoglycemia. ***Hypoglycemia*** - **Hypoglycemia** refers to abnormally low blood glucose levels and is typically managed by consuming glucose. - It does not directly cause foot ulcers but is a complication of diabetes management [2]. *Neuropathy* - **Diabetic neuropathy** leads to loss of protective sensation, making patients unaware of minor injuries or pressure points on their feet [1]. - This lack of sensation makes the foot vulnerable to repeated trauma and ulceration [2], [3]. *Microangiopathy* - **Microangiopathy** in diabetes affects small blood vessels, impairing blood flow to the skin and peripheral tissues of the feet. - Reduced blood supply compromises tissue healing and increases susceptibility to infection, contributing to ulcer formation [4]. *Macroangiopathy* - **Macroangiopathy** involves large blood vessels, leading to **peripheral artery disease** which reduces blood flow to the feet [1]. - Poor circulation impedes wound healing and increases the risk of infection, making ulcers more likely and harder to treat [3].

Q: What percentage of cold thyroid nodules are malignant?

10-20%. ***10-20%*** - While a **cold thyroid nodule** indicates reduced or absent uptake of radioactive iodine, suggesting a non-functional status, the vast majority are **benign** [1]. - A malignancy rate of **10-20%** is consistent with current epidemiological data for these nodules [1]. *70-80%* - This percentage is **significantly higher** than the actual malignancy rate observed in cold thyroid nodules. - Such a high rate would imply that most cold nodules are cancerous, which is **not true** clinically [1]. *50-60%* - This range is a substantial **overestimation** of the malignancy risk associated with cold thyroid nodules. - If half or more of cold nodules were malignant, the clinical approach to their management would be **much more aggressive** [1]. *40-50%* - This percentage is also a **considerable overestimation** and does not reflect the typical malignancy rate. - Thyroid nodules, even cold ones, are far more frequently **benign** than malignant [1].

Q: Comment on the diagnosis of this patient with hypokalemic periodic paralysis.

Grave's disease. ***Grave's disease*** - **Hypokalemic periodic paralysis (HPP)** is a rare but well-recognized complication of **thyrotoxicosis**, particularly in **Asian males**. - The elevated thyroid hormones in Grave's disease can lead to increased activity of the **Na+/K+-ATPase pump**, driving potassium from the extracellular to the intracellular space, causing hypokalemia and muscle paralysis. *Rhinophyma* - **Rhinophyma** is a skin condition characterized by a large, red, bumpy, or bulbous nose, typically associated with **severe rosacea**. - It has no known association with hypokalemic periodic paralysis or thyroid disorders. *Buphthalmos* - **Buphthalmos** refers to the enlargement of the globe of the eye, often seen in **congenital glaucoma** due to increased intraocular pressure. - It is not related to hypokalemic periodic paralysis or thyroid dysfunction. *Pheochromocytoma* - While **pheochromocytoma** can cause **secondary hypertension** and electrolyte disturbances such as hypokalemia due to renin-angiotensin-aldosterone system activation, it does not typically cause **periodic paralysis**. - The hypokalemia in pheochromocytoma is usually due to increased renal potassium excretion rather than a shift into cells, which is characteristic of HPP.

Q: In Klinefelter syndrome, which of the following statements is false?

Hypoplastic male external genitalia. ***Hypoplastic male external genitalia*** - This statement is false because individuals with **Klinefelter syndrome** typically have **normal male external genitalia**, though the testes are usually small and firm [1], [2]. - The condition is characterized by the presence of an extra X chromosome (47, XXY), which affects testicular development, leading to **dysgenesis of the seminiferous tubules** and subsequent hormonal imbalances [2]. *Negative feedback on FSH and LH is lost* - This statement is true because the **dysfunctional testes** in Klinefelter syndrome produce very little **inhibin** and **testosterone**. - This lack of negative feedback to the pituitary results in **elevated levels of FSH and LH** [2]. *Increased Androstenedione levels* - This statement is true, although it is an indirect effect. In Klinefelter syndrome, there is **hypergonadotropic hypogonadism** which leads to an increase in **gonadotropins (LH and FSH)** [3]. - Increased LH can stimulate adrenal production of **androstenedione**, and peripheral aromatization of androstenedione can contribute to higher estrogen levels typical in these patients. *Most common cause of secondary testicular failure* - This statement is true; Klinefelter syndrome is considered the most common genetic cause of **primary hypogonadism**. - Testicular failure in Klinefelter syndrome is usually primary (due to testicular dysfunction), but the hormonal dysregulation can lead to secondary effects [3].

Question 1

What is the most common cause of hypothyroidism in pregnancy?

Accepted Answer

Autoimmune thyroiditis

Answer

Nutritional

Answer

Irradiation

Answer

Anti thyroid drugs ie iatrogenic

Question 2

What is the best screening test for pheochromocytoma?

Accepted Answer

Urinary metanephrine

Answer

Clonidine suppression test

Answer

Serum catecholamine estimation

Answer

Urinary VMA estimation

Question 3

A 24-year-old accountant complains of a white discharge from his breasts. He is most likely experiencing which one of the following conditions?

Accepted Answer

A prolactinoma

Answer

Deficient testosterone receptors in the mammary glands

Answer

A tumor of the posterior pituitary that could be surgically removed

Answer

Excessive production of OT in the hypothalamus

Question 4

Hirsutism is seen in all except:

Accepted Answer

Hypothyroidism

Answer

Acromegaly

Answer

Arrhenoblastoma

Answer

PCOD

Question 5

VIPoma is associated with which syndrome?

Accepted Answer

Verner-Morrison syndrome

Answer

Cushing's syndrome

Answer

Carcinoid syndrome (serotonin syndrome)

Answer

Zollinger-Ellison syndrome

Question 6

All of the following are seen in MEN 2B except which of the following?

Accepted Answer

Hyperparathyroidism

Answer

Neuromas

Answer

Pheochromocytoma

Answer

Medullary carcinoma thyroid

Question 7

Foot ulcers in diabetes are due to all except which of the following?

Accepted Answer

Hypoglycemia

Answer

Microangiopathy

Answer

Macroangiopathy

Answer

Neuropathy

Question 8

What percentage of cold thyroid nodules are malignant?

Accepted Answer

10-20%

Answer

70-80%

Answer

50-60%

Answer

40-50%

Question 9

Comment on the diagnosis of this patient with hypokalemic periodic paralysis.

Accepted Answer

Grave's disease

Answer

Rhinophyma

Answer

Buphthalmos

Answer

Pheochromocytoma

Question 10

In Klinefelter syndrome, which of the following statements is false?

Accepted Answer

Hypoplastic male external genitalia

Answer

Negative feedback on FSH and LH is lost

Answer

Increased Androstenedione levels

Answer

Most common cause of secondary testicular failure

Endocrinology — MCQs

Endocrinology — MCQs

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