Endocrinology Practice Questions

Q: Which is the screening test for acromegaly?

Serum IGF-1. **Explanation:** The diagnosis of acromegaly relies on understanding the physiological secretion of Growth Hormone (GH). **1. Why Serum IGF-1 is the Correct Answer:** Serum **Insulin-like Growth Factor-1 (IGF-1)** is the preferred **screening test** because it has a long half-life and maintains stable plasma concentrations throughout the day. Unlike GH, which is secreted in pulsatile bursts and can be influenced by stress, exercise, or sleep, IGF-1 levels reflect the integrated GH secretion over the preceding 24 hours [2]. A normal age- and sex-matched IGF-1 level effectively rules out acromegaly [1]. **2. Why the Other Options are Incorrect:** * **Serum IGF-2 (A):** This factor is primarily involved in fetal development and is not used in the diagnostic algorithm for GH disorders. * **Oral Glucose Tolerance Test (B):** The 75g OGTT is the **gold standard confirmatory test**, not the screening test [1]. In a healthy individual, hyperglycemia suppresses GH to <1 ng/mL; failure of suppression confirms acromegaly. * **GH levels (C):** Random GH measurements are unreliable for screening due to the hormone's pulsatile nature and short half-life [2]. A single low value does not rule out the disease, and a single high value does not confirm it. **Clinical Pearls for NEET-PG:** * **Best Screening Test:** Serum IGF-1. * **Best Confirmatory Test:** GH suppression test (OGTT). * **Most Common Cause:** Pituitary Adenoma (Somatotroph adenoma). * **Imaging of Choice:** MRI of the Sella Turcica (performed after biochemical confirmation). * **Treatment of Choice:** Transsphenoidal surgery (except in cases where medical management with Somatostatin analogues like Octreotide is preferred) [1].

Q: What is the most common differential diagnosis of hyperthyroidism in a young female?

Anxiety neurosis. **Explanation:** The correct answer is **Anxiety neurosis** (Generalized Anxiety Disorder/Panic Disorder). Hyperthyroidism and Anxiety neurosis share a significant overlap in clinical presentation, particularly in young females, where both conditions are highly prevalent. The underlying medical concept is the **hyper-adrenergic state** seen in both. Common symptoms include tachycardia, palpitations, tremors, heat intolerance, diaphoresis, and irritability. In a clinical setting, a young female presenting with these symptoms must be screened for both thyroid dysfunction (via TSH/T4 levels) and psychiatric disorders to avoid misdiagnosis. **Analysis of Incorrect Options:** * **Hysteria (Dissociative/Conversion Disorder):** This typically presents with neurological deficits (paralysis, blindness, seizures) that cannot be explained by organic pathology. It does not mimic the systemic sympathomimetic symptoms of hyperthyroidism. * **Essential Tremor:** While both involve tremors, essential tremor is usually postural or kinetic and lacks the systemic features of hyperthyroidism like weight loss, tachycardia, or eye signs. * **Parkinsonism:** This is characterized by a "pill-rolling" resting tremor, bradykinesia, and rigidity. It is rare in young females and the tremor type is distinct from the fine, rapid tremor seen in thyrotoxicosis. **High-Yield Clinical Pearls for NEET-PG:** * **The "Fine Tremor":** Both hyperthyroidism and anxiety produce a fine, rapid tremor of the outstretched hands. * **Distinguishing Feature:** In hyperthyroidism, tachycardia often persists during **sleep**, whereas in anxiety neurosis, the heart rate typically normalizes when the patient is asleep. * **Weight Change:** Hyperthyroidism is associated with weight loss despite an increased appetite; anxiety may cause weight fluctuations but lacks the metabolic drive of thyrotoxicosis.

Q: Normal stature with minimal or absent pubertal development may be seen in which of the following conditions?

Kallmann syndrome. **Explanation:** The key to this question lies in the combination of **normal stature** and **absent pubertal development** (primary amenorrhea). **Kallmann Syndrome (Correct Answer):** This is a form of **hypogonadotropic hypogonadism** caused by the failure of GnRH-secreting neurons to migrate from the olfactory placode to the hypothalamus. * **Puberty:** Absent or minimal due to low FSH/LH and subsequent low estrogen. * **Stature:** Stature is **normal or even tall**. Because estrogen is required for the closure of epiphyseal plates, its absence leads to delayed bone age and continued long bone growth. * **Classic Sign:** Anosmia or hyposmia. **Why the other options are incorrect:** * **Testicular Feminization (AIS):** These patients have **normal pubertal development** (specifically breast development, Tanner Stage IV-V) due to the peripheral conversion of testosterone to estrogen, though they lack axillary/pubic hair. * **Pure Gonadal Dysgenesis (46,XX or 46,XY Swyer Syndrome):** While these patients have primary amenorrhea and normal/tall stature, Kallmann syndrome is a more classic association with "minimal development" in a generalized endocrine context. However, the distinguishing feature for Kallmann is the hypothalamic origin and associated anosmia. * **Turner Syndrome (45,XO):** This is characterized by **short stature** (due to SHOX gene haploinsufficiency) and streak ovaries. It does not present with normal stature. **High-Yield Clinical Pearls for NEET-PG:** * **Kallmann Syndrome:** Hypogonadotropic hypogonadism + Anosmia + Normal/Tall stature. * **Turner Syndrome:** Hypergonadotropic hypogonadism + Short stature + Webbed neck + Bicuspid aortic valve. * **Swyer Syndrome:** 46,XY with streak ovaries; requires gonadectomy due to high risk of gonadoblastoma. * **Bone Age:** In Kallmann and Turner syndromes, bone age is typically delayed compared to chronological age.

Q: In which condition is an intravenous glucose tolerance test typically performed?

Gastrectomy. The **Oral Glucose Tolerance Test (OGTT)** is the standard diagnostic tool for diabetes [2]. However, it relies on normal gastric emptying and intestinal absorption. In patients who have undergone a **Gastrectomy** (Option C), the "gastric brake" is lost, leading to abnormally rapid gastric emptying [1]. This causes a rapid surge in blood glucose followed by an exaggerated insulin response (Alimentary Hypoglycemia/Dumping Syndrome). Because the oral route yields unreliable, "lag-storage" type curves in these patients, the **Intravenous Glucose Tolerance Test (IVGTT)** is preferred to bypass the gastrointestinal tract and assess pancreatic beta-cell function directly. **Analysis of Incorrect Options:** * **A. Children:** OGTT is the standard for children when diabetes is suspected, though it is less frequently required than in adults. * **B. Pregnancy:** This is the most common indication for **OGTT** (specifically the 75g or 100g test) to screen for Gestational Diabetes Mellitus (GDM). The IVGTT is not used as it does not reflect the physiological challenge of a meal. * **C. Old Age:** Aging is associated with decreased glucose tolerance, but the standard OGTT remains the diagnostic method of choice. **NEET-PG High-Yield Pearls:** * **IVGTT Procedure:** 0.5 g/kg of glucose is given as a 25% solution over 2–4 minutes. * **K-value:** The result of an IVGTT is expressed as the "glucose disappearance rate" (K-value). A K-value < 1.0 is suggestive of diabetes. * **Indications for IVGTT:** Malabsorption syndromes, chronic diarrhea, and post-gastric surgery (Gastrectomy/Gastrojejunostomy) [1]. * **Diagnostic Choice:** While IVGTT exists, the **HbA1c** and **Fasting Plasma Glucose** are now the primary clinical tools, with OGTT reserved for pregnancy.

Q: A young woman presents with secondary amenorrhea and galactorrhea. MRI shows a pituitary tumor of less than 10mm diameter. What is the recommended treatment?

Bromocriptine. **Explanation:** The clinical presentation of secondary amenorrhea and galactorrhea, combined with an MRI showing a pituitary tumor <10 mm (Microadenoma), is diagnostic of a **Microprolactinoma**. **Why Bromocriptine is the Correct Answer:** In cases of prolactinomas, medical management is the first-line treatment regardless of the tumor size (micro or macro). **Dopamine agonists** like Bromocriptine or Cabergoline are the drugs of choice. They work by stimulating D2 receptors on lactotrophs, which inhibits prolactin secretion and leads to a reduction in tumor size. This restores the pulsatile secretion of GnRH, thereby correcting amenorrhea and stopping galactorrhea. **Why Other Options are Incorrect:** * **Hormonal therapy (Withdrawal bleeding):** This treats the symptom (amenorrhea) but not the underlying cause (hyperprolactinemia). It will not shrink the tumor or stop galactorrhea. * **Radiotherapy:** This is reserved for aggressive tumors or cases refractory to medical and surgical management due to the risk of panhypopituitarism. * **Chemotherapy:** Prolactinomas are benign tumors and do not respond to conventional cytotoxic chemotherapy. **High-Yield Clinical Pearls for NEET-PG:** * **Microadenoma:** <10 mm; **Macroadenoma:** ≥10 mm. * **Drug of Choice:** **Cabergoline** is currently preferred over Bromocriptine due to higher efficacy and fewer side effects (longer half-life), but Bromocriptine remains a standard answer in exams, especially for patients desiring pregnancy. * **Surgical Indication:** Transsphenoidal surgery is indicated only if the patient is resistant to/intolerant of dopamine agonists or if a macroadenoma causes visual field defects (bitemporal hemianopia). * **Hook Effect:** Extremely high prolactin levels can sometimes result in a falsely low lab reading; serial dilution is required for diagnosis.

Q: What is the investigation of choice for diagnosing primary hypothyroidism?

Elevated TSH. Explanation: In **Primary Hypothyroidism**, the pathology lies within the thyroid gland itself, leading to reduced production of thyroid hormones [4]. Due to the intact negative feedback loop, the anterior pituitary responds to low circulating T4 levels by increasing the secretion of **Thyroid Stimulating Hormone (TSH)** [1]. **1. Why Elevated TSH is the Correct Answer:** TSH is the most sensitive and specific screening test for primary hypothyroidism [2]. Because of the logarithmic relationship between TSH and free T4, even a minor decrease in T4 results in a significant, disproportionate rise in TSH. Therefore, an elevated TSH is the first biochemical marker to change, often rising even when T4 levels are still within the normal range (Subclinical Hypothyroidism) [2]. **2. Why the other options are incorrect:** * **Decreased free T3:** T3 is not a sensitive indicator of hypothyroidism and should not be requested [2]. The body compensates by increasing the peripheral conversion of T4 to T3; thus, T3 levels often remain normal even in significant disease. * **Decreased free T4:** While low fT4 confirms overt hypothyroidism, it is not the "investigation of choice" because it may remain normal in early or subclinical stages [2]. * **Anti-TPO antibodies:** These are used to determine the *etiology* (e.g., Hashimoto’s Thyroiditis) [3] rather than to diagnose the functional state of hypothyroidism itself. **Clinical Pearls for NEET-PG:** * **Best Screening Test:** Serum TSH. * **Best Monitoring Parameter:** Serum TSH (checked 6–8 weeks after starting Levothyroxine) [3]. * **Secondary (Central) Hypothyroidism:** TSH will be low or inappropriately normal, and fT4 will be low [2]. In this specific case, TSH is *not* a reliable diagnostic tool. * **Subclinical Hypothyroidism:** Elevated TSH with a normal free T4 [2].

Q: Primary hypothyroidism is seen in all EXCEPT?

Bexarotene. **Explanation:** The key to this question lies in distinguishing between **Primary** and **Central (Secondary/Tertiary)** hypothyroidism [1]. **Correct Answer: D. Bexarotene** Bexarotene is a selective Retinoid X Receptor (RXR) agonist used in the treatment of cutaneous T-cell lymphoma. It causes **Central Hypothyroidism** by suppressing the thyrotropin ̢-subunit gene expression, leading to a profound suppression of TSH secretion. Unlike primary hypothyroidism, patients on Bexarotene will show low T4 levels with a low or inappropriately normal TSH [1]. **Why the other options are incorrect (Causes of Primary Hypothyroidism):** * **A. Iodine Deficiency:** The most common cause of primary hypothyroidism worldwide. Lack of iodine prevents the synthesis of T3 and T4, leading to a compensatory rise in TSH. * **B. Iodine Excess:** High doses of iodine can inhibit the organification of iodine and the synthesis of thyroid hormones, a phenomenon known as the **Wolff-Chaikoff effect**. While usually transient, it can lead to permanent primary hypothyroidism in patients with underlying thyroid disease. * **C. Lithium:** Lithium inhibits the release of thyroid hormones from the thyroid gland. It is a well-known pharmacological cause of primary hypothyroidism and goiter. **High-Yield Clinical Pearls for NEET-PG:** * **Wolff-Chaikoff Effect:** Autoregulation where excess iodine inhibits thyroid hormone synthesis. * **Jod-Basedow Phenomenon:** Iodine-induced hyperthyroidism (opposite of Wolff-Chaikoff). * **Amiodarone:** A high-yield drug that can cause both hypothyroidism (via Wolff-Chaikoff) and hyperthyroidism (Type 1 and Type 2) [2]. * **TSH Levels:** In Primary Hypothyroidism, TSH is **elevated**. In Central Hypothyroidism (e.g., Bexarotene, Pituitary adenoma), TSH is **low or normal** [1].

Question 1

Which is the screening test for acromegaly?

Accepted Answer

Serum IGF-1

Answer

Serum IGF-2

Answer

Oral glucose tolerance test

Answer

GH levels

Question 2

In parathyroid crisis with sudden elevations of calcium over 16 mg/dL, what is the appropriate initial treatment?

Accepted Answer

Parathyroidectomy for removal of adenoma

Answer

Thyrocalcitonin

Answer

Intravenous bicarbonate

Answer

Intravenous fluids and loop diuretics

Question 3

What is the most common differential diagnosis of hyperthyroidism in a young female?

Accepted Answer

Anxiety neurosis

Answer

Hysteria

Answer

Essential tremor

Answer

Parkinsonism

Question 4

Normal stature with minimal or absent pubertal development may be seen in which of the following conditions?

Accepted Answer

Kallmann syndrome

Answer

Testicular feminization

Answer

Pure gonadal dysgenesis

Answer

Turner syndrome

Question 5

In which condition is an intravenous glucose tolerance test typically performed?

Accepted Answer

Gastrectomy

Answer

Children

Answer

Pregnancy

Answer

Old age

Question 6

Diabetic amyotrophy characteristically presents with which of the following?

Accepted Answer

Pain in the anterior thigh

Answer

Third nerve palsy with pupillary sparing

Answer

Distal areflexia

Answer

Asymmetric motor weakness

Question 7

A young woman presents with secondary amenorrhea and galactorrhea. MRI shows a pituitary tumor of less than 10mm diameter. What is the recommended treatment?

Accepted Answer

Bromocriptine

Answer

Hormonal therapy for withdrawal bleeding

Answer

Radiotherapy

Answer

Chemotherapy

Question 8

A 40-year-old male presented with a 2-month history of watery diarrhea and periodic abdominal pain. Examination revealed a warm face, facial engorgement with blood, itching, sweating, and a diastolic murmur in the left 4th intercostal space, parasternal, which increased with inspiration. Lab findings showed increased 5-HIAA secretion in urine. Colonoscopy was performed, and a biopsy of a mass stained positive for chromogranin. With which of the following syndromes may the above condition be associated?

Accepted Answer

Wermer syndrome

Answer

Sipple syndrome

Answer

Neurofibromatosis

Answer

Tuberous sclerosis

Question 9

What is the investigation of choice for diagnosing primary hypothyroidism?

Accepted Answer

Elevated TSH

Answer

Decreased free T3

Answer

Decreased free T4

Answer

Anti-TPO antibodies

Question 10

Primary hypothyroidism is seen in all EXCEPT?

Accepted Answer

Bexarotene

Answer

Iodine deficiency

Answer

Iodine excess

Answer

Lithium

Endocrinology — MCQs

Endocrinology — MCQs

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