Pituitary Disorders — MCQs
A child has serum osmolality of 270 mOsm/kg and urine osmolality of 1200 mOsm/kg. What is the most probable diagnosis?
A major causal factor in some cases of hypogonadism is:
Which of the following is the drug of choice for the treatment of Syndrome of Inappropriate Antidiuretic Hormone secretion?
Prolactin secreting gland develops from -
Which of the following is not true about syndrome of inappropriate antidiuretic hormone secretion (SIADH)?
Which of the following statements are correct regarding the management of gastrointestinal bleeding in children? I. Somatostatin or octreotide infusion should be given for at least 7 days after stoppage of initial bleeding to prevent rebleeding II. Endoscopic Sclerotherapy (EST) involves endoscopic injection of N -butyl-2-cyanoacrylate or iso-butyl-2-cyanoacrylate III. EST has upto 90 % efficacy in controlling acute bleeding IV. Following an episode of acute variceal bleeding, all patients should receive secondary prophylaxis to prevent rebleeding Select the answer using the code given below :
A 3-week-old female infant presents with ambiguous genitalia and hyperpigmentation of the skin. Laboratory findings include hyponatremia and hyperkalemia. What is the most likely diagnosis?
Deep white matter lesion with bilateral deep bright thalamic appearance is suggestive of which condition?
Cretinism is characterized by which of the following physical features?
Screening of neonatal thyroid disease is done by?
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 major causal factor in some cases of hypogonadism is:
- A. Reduced secretion of gonadotropin-releasing hormone (GnRH) (Correct Answer)
- B. Excess secretion of testicular activin by Sertoli cells
- C. Hypersecretion of pituitary LH and FSH as the result of increased GnRH
- D. Failure of the hypothalamus to respond to testosterone
Explanation: ***Reduced secretion of gonadotropin-releasing hormone (GnRH)*** - **Hypogonadotropic hypogonadism** is characterized by low levels of LH and FSH due to inadequate GnRH secretion from the hypothalamus, leading to decreased testosterone production. - This can be caused by various factors, including genetic conditions, hypothalamic tumors, or functional suppression from stress or severe illness. *Excess secretion of testicular activin by Sertoli cells* - **Activin** promotes FSH synthesis and secretion from the pituitary but is not a primary cause of hypogonadism. - While disruptions in activin/inhibin balance can affect spermatogenesis, it doesn't directly cause a systemic hypogonadal state through its direct effect on GnRH or gonadal function. *Hypersecretion of pituitary LH and FSH as the result of increased GnRH* - **Hypersecretion of LH and FSH** in response to increased GnRH would lead to **hypergonadism**, or at least eugonadism, not hypogonadism. - This scenario would stimulate excessive testosterone production, the opposite of hypogonadism. *Failure of the hypothalamus to respond to testosterone* - The hypothalamus, as well as the pituitary, are sensitive to **negative feedback from testosterone** to regulate GnRH and gonadotropin release. - A failure to respond to testosterone would typically lead to **increased GnRH and gonadotropin secretion** (as the feedback loop is broken), resulting in higher testosterone levels, which contradicts hypogonadism.
Question 3: Which of the following is the drug of choice for the treatment of Syndrome of Inappropriate Antidiuretic Hormone secretion?
- A. Demeclocycline (Correct Answer)
- B. Chlorpropamide
- C. Vasopressin
- D. Thiazide diuretics
Explanation: ***Demeclocycline*** - **Demeclocycline** is a **tetracycline antibiotic** that inhibits the action of ADH on the renal tubules, promoting excretion of water. - This effect helps to correct the **hyponatremia** and fluid retention seen in SIADH. - It is considered the **classic drug of choice** for chronic SIADH management, though newer agents like vaptans are increasingly used. *Chlorpropamide* - **Chlorpropamide** is a **sulfonylurea** medication primarily used for **type 2 diabetes mellitus** to stimulate insulin release. - It can **potentiate ADH action**, which would worsen SIADH rather than treat it. *Vasopressin* - **Vasopressin** (also known as ADH) is the **hormone** whose excessive secretion is the underlying problem in SIADH. - Administering vasopressin would **aggravate** the condition by increasing water reabsorption and worsening hyponatremia. *Thiazide diuretics* - **Thiazide diuretics** can **worsen hyponatremia** by impairing the kidney's ability to dilute urine and excrete free water. - This makes them **contraindicated in SIADH** management. - They are used in conditions like **hypertension** or paradoxically in **nephrogenic diabetes insipidus** (where they reduce urine output), but not for treating SIADH.
Question 4: 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.
Question 5: Which of the following is not true about syndrome of inappropriate antidiuretic hormone secretion (SIADH)?
- A. Patient can be clinically euvolemic to hypovolemic
- B. Urine osmolality >100 mOsm/kg
- C. Urinary sodium <20 mEq/L (Correct Answer)
- D. Serum sodium <135 mEq/L
Explanation: ***Urinary sodium <20 mEq/L*** - In **SIADH**, the inappropriate secretion of ADH leads to increased water reabsorption, causing **dilutional hyponatremia**. [1] - The kidneys respond by trying to excrete excess water and dilute the urine, leading to **increased urinary sodium concentration**, typically *greater than* 20 mEq/L. *Patient can be clinically euvolemic to hypovolemic* - Patients with **SIADH** are typically **euvolemic** because the excess water is retained intracellularly and extracellularly in balanced proportions, without significant edema or dehydration. [1] - While fluid retention occurs, it's not enough to cause significant clinical volume overload, and they are never truly hypovolemic. *Urine osmolality >100 mOsm/kg* - In **SIADH**, the continued action of **ADH** despite hypotonicity results in the reabsorption of water, leading to the production of **concentrated urine**. [1] - This elevated urine osmolality, typically **greater than 100 mOsm/kg**, indicates an inability to adequately excrete free water. [1] *Serum sodium <135 mEq/L* - **SIADH** is defined by **hyponatremia**, a serum sodium concentration **below 135 mEq/L**, due to the excessive retention of water. - This dilutes the extracellular fluid, leading to a reduction in the relative concentration of sodium.
Question 6: Which of the following statements are correct regarding the management of gastrointestinal bleeding in children? I. Somatostatin or octreotide infusion should be given for at least 7 days after stoppage of initial bleeding to prevent rebleeding II. Endoscopic Sclerotherapy (EST) involves endoscopic injection of N -butyl-2-cyanoacrylate or iso-butyl-2-cyanoacrylate III. EST has upto 90 % efficacy in controlling acute bleeding IV. Following an episode of acute variceal bleeding, all patients should receive secondary prophylaxis to prevent rebleeding Select the answer using the code given below :
- A. III and IV (Correct Answer)
- B. I and III
- C. II and IV
- D. I and II
Explanation: ***III and IV*** **Statement I is INCORRECT:** Somatostatin or octreotide infusions are typically administered for **3-5 days** (not 7 days) after initial bleeding has stopped to prevent rebleeding. Prolonged use beyond this period is not generally recommended due to potential side effects and lack of additional benefit. **Statement II is INCORRECT:** Endoscopic Sclerotherapy (EST) for esophageal varices involves injection of sclerosants such as **ethanolamine oleate, sodium tetradecyl sulfate**, or polidocanol. The tissue adhesives **N-butyl-2-cyanoacrylate** or **iso-butyl-2-cyanoacrylate** are used in **endoscopic variceal obturation (EVO)** for **gastric varices**, not in standard sclerotherapy for esophageal varices. **Statement III is CORRECT:** Endoscopic Sclerotherapy (EST) demonstrates **up to 90% efficacy** in controlling acute variceal bleeding, making it a highly effective intervention for managing acute hemorrhage. **Statement IV is CORRECT:** Following an episode of acute variceal bleeding, **all patients should receive secondary prophylaxis** (typically combination of non-selective beta-blockers and endoscopic band ligation) to prevent rebleeding, which is associated with significant morbidity and mortality. *I and III* - Incorrect because Statement I is wrong about the duration of vasoactive drug therapy. *II and IV* - Incorrect because Statement II confuses sclerotherapy agents with tissue adhesives used for gastric varices. *I and II* - Incorrect because both statements I and II contain inaccuracies regarding duration of therapy and sclerosing agents respectively.
Question 7: A 3-week-old female infant presents with ambiguous genitalia and hyperpigmentation of the skin. Laboratory findings include hyponatremia and hyperkalemia. What is the most likely diagnosis?
- A. 21 hydroxylase deficiency (Correct Answer)
- B. 17 alpha hydroxylase deficiency
- C. 17, 20 lyase deficiency
- D. 11 beta hydroxylase deficiency
Explanation: **Explanation:** The clinical presentation of ambiguous genitalia in a female infant, skin hyperpigmentation, and electrolyte imbalances (hyponatremia and hyperkalemia) is classic for **Congenital Adrenal Hyperplasia (CAH)**, specifically **21-hydroxylase deficiency**. **1. Why 21-hydroxylase deficiency is correct:** This is the most common cause of CAH (>90%). A deficiency in this enzyme blocks the conversion of progesterone to deoxycorticosterone (mineralocorticoid pathway) and 17-OH progesterone to 11-deoxycortisol (glucocorticoid pathway). * **Mineralocorticoid deficiency:** Leads to "salt-wasting" (hyponatremia, hyperkalemia, and hypotension). * **Glucocorticoid deficiency:** Triggers a feedback increase in ACTH, causing **hyperpigmentation** (due to shared precursor with MSH) and adrenal hyperplasia. * **Androgen excess:** Shunting of precursors toward the androgen pathway causes virilization/ambiguous genitalia in females. **2. Why other options are incorrect:** * **11-beta hydroxylase deficiency:** While it causes virilization and hyperpigmentation, it leads to **hypertension** and hypokalemia because 11-deoxycortisol (which builds up) has mineralocorticoid activity. * **17-alpha hydroxylase deficiency:** This results in decreased sex hormones. Females would have normal external genitalia at birth but fail puberty; males would present with ambiguous genitalia/pseudohermaphroditism. It also causes hypertension. * **17, 20 lyase deficiency:** This affects only sex hormone synthesis. It does not cause salt-wasting or hyperpigmentation as cortisol and aldosterone pathways remain intact. **High-Yield Pearls for NEET-PG:** * **Most common enzyme deficiency:** 21-hydroxylase. * **Diagnostic marker:** Elevated **17-hydroxyprogesterone (17-OHP)**. * **Karyotype:** Usually 46, XX in virilized females. * **Treatment:** Glucocorticoid (Hydrocortisone) and Mineralocorticoid (Fludrocortisone) replacement.
Question 8: Deep white matter lesion with bilateral deep bright thalamic appearance is suggestive of which condition?
- A. Alexander disease
- B. Canavan's disease
- C. Krabbe's disease (Correct Answer)
- D. Metachromatic leukodystrophy
Explanation: ### Explanation **Krabbe’s Disease (Globoid Cell Leukodystrophy)** The correct answer is **Krabbe’s Disease**. This is an autosomal recessive lysosomal storage disorder caused by a deficiency of the enzyme **Galactocerebrosidase (GALC)**, leading to the accumulation of psychosine, which is toxic to oligodendrocytes. The characteristic neuroimaging finding in the early infantile stage is **hyperdensity (on CT)** or **T2-weighted hypointensity/T1-weighted hyperintensity (on MRI)** in the **thalami**, caudate nuclei, and posterior limb of the internal capsule. This "bright thalamus" appearance, combined with symmetric demyelination of the deep white matter and cerebellar involvement, is a classic diagnostic clue for Krabbe’s. **Analysis of Incorrect Options:** * **Alexander Disease:** Characterized by **frontal lobe predominance** of white matter lesions and "Rosenthal fibers" on pathology. It often presents with macrocephaly. * **Canavan’s Disease:** Notable for **diffuse** white matter involvement including the **subcortical U-fibers** (which are spared in Krabbe’s and MLD) and elevated N-acetylaspartate (NAA) on MR spectroscopy. It also presents with macrocephaly. * **Metachromatic Leukodystrophy (MLD):** Shows a characteristic **"tigroid" or "leopard skin" pattern** of demyelination due to the sparing of perivascular white matter. It typically spares the thalami in early stages. **High-Yield Clinical Pearls for NEET-PG:** * **Krabbe’s:** Look for "Globoid cells" (multinucleated macrophages) on brain biopsy and optic atrophy. * **Macrocephaly + Leukodystrophy:** Think Alexander disease or Canavan’s disease. * **Microcephaly + Leukodystrophy:** Think Krabbe’s disease. * **Tigroid Pattern:** Pathognomonic for MLD (Arylsulfatase A deficiency).
Question 9: Cretinism is characterized by which of the following physical features?
- A. Disproportionate dwarfism (Correct Answer)
- B. Short stature with a long trunk
- C. Short stature with a short trunk
- D. Long stature with a long trunk
Explanation: **Explanation:** **Cretinism** (Congenital Hypothyroidism) results from a deficiency of thyroid hormones during fetal or neonatal life. Thyroid hormone is essential for skeletal maturation and linear growth. In its absence, there is a significant delay in bone age and the maturation of the epiphyseal centers. **Why Option A is Correct:** The hallmark of cretinism is **disproportionate dwarfism**. Thyroid hormone is critical for the growth of long bones. When deficient, the limbs remain short while the trunk continues to grow relatively more, leading to a **low upper segment to lower segment (US:LS) ratio** for the child's age (retaining the infantile proportions where the upper segment is longer). This is distinct from growth hormone deficiency, which typically causes proportionate dwarfism. **Why Other Options are Incorrect:** * **Options B & C:** These descriptions are inaccurate. While the trunk may appear "long" relative to the limbs, the standard clinical terminology is "disproportionate." Short-trunk dwarfism is more characteristic of skeletal dysplasias like Morquio syndrome. * **Option D:** Hypothyroidism leads to growth retardation, not long stature. **Clinical Pearls for NEET-PG:** * **Most common cause:** Thyroid dysgenesis (Ectopic thyroid is the most common specific etiology). * **Early signs:** Prolonged physiological jaundice, poor feeding, constipation, and a large posterior fontanelle (>0.5 cm). * **Classic triad:** Coarse facies, macroglossia (large tongue), and umbilical hernia. * **Radiology:** Absence of the distal femoral epiphysis at birth is a strong indicator of in utero hypothyroidism. * **Treatment:** Levothyroxine (T4) must be started within the first 2 weeks of life to prevent permanent intellectual disability.
Question 10: Screening of neonatal thyroid disease is done by?
- A. T4
- B. T3
- C. TSH (Correct Answer)
- D. TPO antibodies
Explanation: **Explanation:** **1. Why TSH is the Correct Answer:** Congenital Hypothyroidism (CH) is one of the most common preventable causes of intellectual disability. The primary screening strategy worldwide, including India, is the measurement of **Thyroid Stimulating Hormone (TSH)**. * **Sensitivity:** TSH is the most sensitive indicator for detecting **Primary Congenital Hypothyroidism** (which accounts for >95% of cases). Even a slight decrease in thyroid hormone production leads to a significant compensatory rise in TSH. * **Timing:** Screening is ideally performed between **48 to 72 hours of life**. This avoids the "physiological TSH surge" that occurs immediately after birth, which can lead to false-positive results. **2. Why Other Options are Incorrect:** * **T4 (Thyroxine):** While some programs use a "Primary T4 with reflex TSH" approach, T4 alone is less specific. It can be low in premature infants or those with TBG (Thyroid Binding Globulin) deficiency, leading to false positives. * **T3 (Triiodothyronine):** T3 levels are often the last to fall in hypothyroidism and can remain normal even in severe cases due to increased peripheral conversion of T4 to T3. It has no role in screening. * **TPO Antibodies:** These are markers for autoimmune thyroiditis (e.g., Hashimoto’s), which is an acquired condition and not a cause of congenital hypothyroidism. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of CH:** Thyroid Dysgenesis (Ectopy is the most common specific type). * **Most common clinical feature:** Most neonates are **asymptomatic** at birth. If present, early signs include a large posterior fontanelle, prolonged physiological jaundice, and umbilical hernia. * **Sample collection:** Done via **heel prick** on a Guthrie card (filter paper). * **Treatment:** Levothyroxine (10–15 μg/kg/day) should be started immediately, ideally within the first 2 weeks of life, to ensure normal neurodevelopment.
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