Pituitary Disorders — MCQs

10 questions

A child has serum osmolality of 270 mOsm/kg and urine osmolality of 1200 mOsm/kg. What is the most probable diagnosis?

A patient with a known brain tumor learns that his pituitary stalk has been affected. Secretion of which of the following hormones is increased after the sectioning of the pituitary stalk?

Most common tumour of the pituitary is -

Which is the most common functioning tumour of pituitary?

What is the initial treatment for most patients with growth hormone-secreting pituitary adenoma?

Hypothyroidism with an increased TSH level is seen in all except which of the following?

A 30-year-old woman presents with a history of amenorrhea and impaired vision of six months' duration. Physical examination shows normal findings except for pale optic discs and diminished visual acuity. The most likely diagnosis is -

Which is false in Congenital Hypopituitarism?

Which of the following is a common finding in patients with Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)?

Q10

Prolactin secreting gland develops from -

Pituitary Disorders Indian Medical PG Practice Questions and MCQs

Question 1: A child has serum osmolality of 270 mOsm/kg and urine osmolality of 1200 mOsm/kg. What is the most probable diagnosis?

A. Nephrogenic diabetes insipidus
B. Water deprivation
C. Central diabetes insipidus
D. SIADH (Correct Answer)

Explanation: SIADH - In SIADH (Syndrome of Inappropriate Antidiuretic Hormone), there is excessive ADH secretion, leading to water retention, low serum osmolality (dilute blood), and concentrated urine. [1] - The serum osmolality of 270 mOsm/kg is low-normal/mildly low [3], while the urine osmolality of 1200 mOsm/kg is very high [1], indicating the kidneys are inappropriately conserving water and concentrating urine despite diluted plasma. Nephrogenic diabetes insipidus - This condition involves the kidneys being unable to respond to ADH [2], leading to the excretion of large volumes of dilute urine despite dehydration. - While serum osmolality might be high due to dehydration, urine osmolality would be low (dilute), contrary to the given values. Water deprivation - In water deprivation, the body compensates by releasing ADH, which leads to concentrated urine to conserve water and a high serum osmolality. - Here, the serum osmolality is low-normal, which does not align with the expected high serum osmolality seen in water deprivation. Central diabetes insipidus - Characterized by the lack of ADH production by the pituitary gland [2], resulting in the excretion of large volumes of dilute urine. - Patients with central DI would typically have high serum osmolality (due to water loss) and low urine osmolality (dilute urine), which is the opposite of the given values.

Question 2: A patient with a known brain tumor learns that his pituitary stalk has been affected. Secretion of which of the following hormones is increased after the sectioning of the pituitary stalk?

A. FSH
B. Prolactin (Correct Answer)
C. TSH
D. ACTH

Explanation: ***Prolactin*** - Prolactin is **unique** among anterior pituitary hormones as it is under **tonic inhibitory control** by dopamine from the hypothalamus. - Sectioning of the pituitary stalk disrupts dopamine delivery via the hypothalamic-hypophyseal portal system. - This leads to a **loss of tonic inhibition**, causing an **increase in prolactin secretion** from the anterior pituitary. - This phenomenon is known as the **"stalk effect"** or **hyperprolactinemia due to stalk section**. *FSH* - **Follicle-stimulating hormone (FSH)** secretion is regulated by **gonadotropin-releasing hormone (GnRH)** from the hypothalamus, which is **stimulatory**. - Stalk section interrupts GnRH delivery via the portal system, leading to a **decrease** in FSH secretion. *TSH* - **Thyroid-stimulating hormone (TSH)** secretion is positively regulated by **thyrotropin-releasing hormone (TRH)** from the hypothalamus. - Interruption of the pituitary stalk reduces TRH delivery, causing a **decrease** in TSH secretion. *ACTH* - **Adrenocorticotropic hormone (ACTH)** secretion is positively regulated by **corticotropin-releasing hormone (CRH)** from the hypothalamus. - Damage to the pituitary stalk diminishes CRH stimulation, resulting in a **decrease** in ACTH secretion.

Question 3: Most common tumour of the pituitary is -

A. ACTH secreting adenoma
B. Prolactinoma (Correct Answer)
C. TSH secreting adenoma
D. GH secreting adenoma

Explanation: ***Prolactinoma*** - **Prolactinomas** are the most frequently occurring type of pituitary adenoma, accounting for approximately **40-50%** of all pituitary tumors [1]. - They are characterized by the **overproduction of prolactin**, leading to symptoms like **galactorrhea**, **amenorrhea**, and **infertility** [1]. *ACTH secreting adenoma* - This type of adenoma leads to **Cushing's disease** due to excessive **ACTH production**, stimulating adrenal cortisol synthesis [2]. - While significant, **ACTH-secreting adenomas** are less common than prolactinomas, accounting for about **15-20%** of pituitary tumors. *TSH secreting adenoma* - **TSH-secreting adenomas** are extremely rare, making up less than **1%** of all pituitary tumors. - They cause secondary hyperthyroidism due to excessive **thyroid-stimulating hormone (TSH)** secretion. *GH secreting adenoma* - **Growth hormone (GH) secreting adenomas** cause **acromegaly** in adults and **gigantism** in children [1]. - These tumors are less common than prolactinomas, constituting about **15-20%** of pituitary adenomas.

Question 4: Which is the most common functioning tumour of pituitary?

A. GH secreting tumor
B. ACTH producing adenoma
C. Prolactinoma (Correct Answer)
D. Oncocytoma

Explanation: ***Prolactinoma*** - Prolactinomas are the **most common type of functioning pituitary tumor**, accounting for approximately 40-50% of all pituitary adenomas [1]. - They lead to **hyperprolactinemia**, causing symptoms such as galactorrhea, amenorrhea, and infertility in women, and hypogonadism and erectile dysfunction in men [1]. *GH secreting tumor* - Growth hormone (GH) secreting tumors cause **acromegaly** in adults and **gigantism** in children [2]. - While significant, they are less common than prolactinomas, typically representing about 15-20% of functioning pituitary tumors. *ACTH producing adenoma* - ACTH producing adenomas lead to **Cushing's disease** via excessive cortisol production [3]. - These tumors are less frequent than prolactinomas, accounting for about 10-15% of functioning pituitary adenomas. *Oncocytoma* - Oncocytomas are a **histological classification** of tumors, not typically defined by specific hormone secretion. - Most pituitary oncocytomas are **non-functioning** and detected due to mass effect rather than hormonal excess.

Question 5: What is the initial treatment for most patients with growth hormone-secreting pituitary adenoma?

A. Transphenoidal surgical resection (Correct Answer)
B. Somatostatin analogs
C. Dopamine agonists
D. GH receptor antagonists

Explanation: ***Transphenoidal surgical resection*** - This is the **preferred initial treatment** for most growth hormone (GH)-secreting pituitary adenomas, as it offers the best chance for **cure** and rapid reduction in GH levels [1]. - Success rates are high, especially for **smaller tumors** (microadenomas), and it can quickly relieve mass effect symptoms [1]. *Somatostatin analogs* - These are typically used as **second-line therapy** if surgery is unsuccessful or contraindicated, or in patients not surgical candidates. - They work by **inhibiting GH secretion** but do not usually achieve a complete cure like surgery. *GH receptor antagonists* - These medications, such as pegvisomant, **block the action of GH** at its receptor, normalizing IGF-1 levels. - They are primarily used when other treatments, including surgery and somatostatin analogs, have failed to control GH excess. *Dopamine agonists* - While dopamine agonists (e.g., cabergoline) can **sometimes reduce GH secretion** in a minority of patients, they are significantly less effective for GH-secreting tumors compared to prolactinomas [1]. - They are occasionally used as **adjunctive therapy** or in specific cases where the GH-secreting tumor also co-secretes prolactin [1].

Question 6: Hypothyroidism with an increased TSH level is seen in all except which of the following?

A. Sheehan's syndrome (Correct Answer)
B. Post radioiodine ablation
C. Endemic goitre
D. Lithium carbonate therapy

Explanation: ***Sheehan's syndrome*** - Sheehan's syndrome is a cause of **secondary hypothyroidism** [4], meaning the problem lies in the **pituitary gland's inability to produce TSH**, leading to low TSH and low thyroid hormones. - In this condition, the TSH level would be **low or inappropriately normal**, not increased, as the pituitary is damaged [2]. *Lithium carbonate therapy* - Lithium can **inhibit thyroid hormone release** and synthesis, leading to **primary hypothyroidism** where the thyroid gland is the culprit. - This results in a feedback loop that causes the pituitary to produce **increased TSH** to try and stimulate the failing thyroid [1]. *Post radioiodine ablation* - Radioiodine ablation **destroys thyroid cells**, leading to a direct inability of the thyroid gland to produce sufficient hormones. - This condition mimics spontaneous primary hypothyroidism, causing the pituitary to release **increased TSH** in an attempt to stimulate the damaged thyroid [1][3]. *Endemic goitre* - Endemic goitre is often caused by **iodine deficiency**, which impairs the thyroid's ability to synthesize thyroid hormones. - This is a form of **primary hypothyroidism** leading to **increased TSH** as the pituitary tries to compensate for the low thyroid hormone levels [1].

Question 7: A 30-year-old woman presents with a history of amenorrhea and impaired vision of six months' duration. Physical examination shows normal findings except for pale optic discs and diminished visual acuity. The most likely diagnosis is -

A. Benign intracranial hypertension
B. Hypothalamic glioma
C. Craniopharyngioma
D. Pituitary adenoma (Correct Answer)

Explanation: ***Pituitary adenoma*** - Pituitary adenomas, particularly **macroadenomas**, can cause **bitemporal hemianopsia** due to compression of the **optic chiasm**, leading to impaired vision and pale optic discs [1]. - They also frequently secrete hormones, with **prolactinomas** being a common type, leading to **amenorrhea** in women due to inhibition of GnRH. *Benign intracranial hypertension* - This condition is primarily characterized by **increased intracranial pressure** leading to headache, pulsatile tinnitus, and **papilledema**, which presents as a swollen optic disc, not pale. - While it can cause visual field defects, **amenorrhea** is not a typical associated symptom. *Hypothalamic glioma* - Hypothalamic gliomas can cause visual field defects and endocrine dysfunction due to their location near the **optic chiasm** and **hypothalamus**. - However, they are more common in children and usually present with symptoms like **diabetes insipidus**, growth abnormalities, or precocious puberty, rather than isolated amenorrhea and optic disc pallor. *Craniopharyngioma* - Craniopharyngiomas are **suprasellar tumors** that can compress the optic chiasm, causing visual disturbances, and impact the pituitary stalk and hypothalamus, leading to endocrine dysfunction. - They often present with symptoms of **hydrocephalus**, **growth retardation**, or **diabetes insipidus**, and are more frequently diagnosed in childhood or adolescence, although they can occur in adults.

Question 8: Which is false in Congenital Hypopituitarism?

A. Hypoglycemia
B. Growth hormone level < 7 ng/ml
C. Baby small at birth (Correct Answer)
D. Delayed puberty

Explanation: ***Baby small at birth*** - This statement is **false** because congenital hypopituitarism typically does not cause **intrauterine growth restriction** or a baby to be small at birth. - Growth hormone (GH) and other pituitary hormones are primarily involved in **postnatal growth**, so infants with this condition are usually of **normal size at birth**. *Hypoglycemia* - **Neonatal hypoglycemia** is a common and often severe manifestation of congenital hypopituitarism, especially due to **GH deficiency** and sometimes ACTH deficiency. - GH and cortisol play crucial roles in **glucose homeostasis**, and their deficiency leads to impaired gluconeogenesis. *Growth hormone level < 7 ng/ml* - A **peak growth hormone level of less than 7 ng/ml** in response to two provocative tests is a common diagnostic criterion for **growth hormone deficiency** in children. - This threshold indicates an inadequate secretion of GH essential for normal growth and metabolism. *Delayed puberty* - **Deficiency of gonadotropins** (LH and FSH) due to hypopituitarism prevents the normal onset and progression of puberty. - This results in features such as **absent or delayed secondary sexual characteristic**s and **incomplete pubertal development**.

Question 9: Which of the following is a common finding in patients with Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)?

A. Ascites
B. Normal BP (Correct Answer)
C. Generalized edema
D. Dry mucous membrane

Explanation: ***Normal BP*** - In SIADH, patients are typically **euvolemic** due to the primary issue being water retention rather than salt retention or frank dehydration [2]. - While hyponatremia occurs, the body's compensatory mechanisms usually prevent significant changes in blood pressure, maintaining it within the **normal range**. *Generalized edema* - Generalized edema is uncommon in SIADH because the excessive water retention is initially within the **intravascular compartment**, and the body attempts to excrete the additional volume of water [1]. - Although the patient is effectively retaining water, the osmolality is low, leading to fluid shifts rather than overt edema unless severe, protracted fluid overload occurs. *Ascites* - **Ascites**, which is the accumulation of fluid in the peritoneal cavity, is not a characteristic feature of SIADH [2]. - Ascites is more commonly associated with conditions like **liver cirrhosis**, heart failure, or malignancy. *Dry mucous membrane* - **Dry mucous membranes** are a sign of dehydration and fluid volume deficit. - In contrast, SIADH involves **fluid overload** (though euvolemic), making dry mucous membranes an unlikely finding [2].

Question 10: Prolactin secreting gland develops from -

A. Infundibulum
B. Rathke's pouch (Correct Answer)
C. Tuber cinereum
D. 3rd ventricle

Explanation: ***Rathke's pouch*** - The **anterior pituitary gland**, which secretes prolactin [2], develops embryologically from **Rathke's pouch**. - Rathke's pouch is an **ectodermal evagination** from the roof of the primitive oral cavity (stomodeum). *Infundibulum* - The **infundibulum** is also known as the pituitary stalk, connecting the hypothalamus to the posterior pituitary [1]. - It is derived from **neuroectoderm** and forms part of the posterior pituitary, not the prolactin-secreting anterior pituitary [1]. *Tuber cinereum* - The **tuber cinereum** is a part of the **hypothalamus**. - It is involved in regulating several bodily functions but does not directly give rise to the prolactin-secreting gland. *3rd ventricle* - The **3rd ventricle** is one of the four ventricles of the brain, filled with **cerebrospinal fluid**. - It is a part of the central nervous system and is not involved in the embryological development of the pituitary gland.

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