Endocrinology Practice Questions

Q: What laboratory test is most appropriate for this patient?

Calcitonin. ***Calcitonin*** - **Calcitonin** is the most specific tumor marker for **medullary thyroid carcinoma (MTC)**, produced by parafollicular **C-cells**. - Elevated serum calcitonin levels help diagnose MTC and monitor treatment response, especially in **MEN 2 syndrome** cases. *Alpha-fetoprotein* - **AFP** is primarily elevated in **hepatocellular carcinoma** and **germ cell tumors** (testicular/ovarian). - It has no association with **thyroid malignancies** and would not be useful for suspected MTC. *Beta2-microglobulin* - **Beta2-microglobulin** is elevated in **multiple myeloma**, **lymphomas**, and other hematologic malignancies. - It is not a marker for **thyroid cancer** and lacks specificity for MTC diagnosis. *Insulin-like growth factor-1* - **IGF-1** is used to diagnose **acromegaly** caused by **growth hormone excess** from pituitary adenomas. - It has no role in thyroid cancer evaluation and is unrelated to **C-cell tumors**.

Q: In osteoporosis, what change occurs?

Decrease in absolute amount of bone mass. Explanation: 1. Why Option A is Correct: Osteoporosis is defined as a systemic skeletal disorder characterized by low bone mass and micro-architectural deterioration of bone tissue [1]. The fundamental pathology is an imbalance between bone resorption (osteoclasts) and bone formation (osteoblasts), leading to a decrease in the absolute amount of bone mass [2]. Crucially, the chemical composition of the remaining bone remains normal (unlike osteomalacia, where mineralization is defective); there is simply "less bone" overall. 2. Why Other Options are Incorrect: * Option B: Osteoporosis is significantly more common in females [1], particularly post-menopausal women, due to the rapid decline in estrogen levels which leads to increased osteoclast activity. * Option C: Radiographs are insensitive for early diagnosis. A plain X-ray only shows decreased bone density (osteopenia) after 30-50% of bone mass has already been lost. The gold standard for diagnosis is the DEXA scan [2]. * Option D: While Hormone Replacement Therapy (HRT) was historically used, it is no longer the first-line treatment due to risks of breast cancer and cardiovascular events. Bisphosphonates (e.g., Alendronate) are the current mainstay of pharmacological management. High-Yield Clinical Pearls for NEET-PG: * WHO Diagnostic Criteria (DEXA): Osteoporosis is defined as a T-score ≤ -2.5 SD. A T-score between -1.0 and -2.5 is termed Osteopenia. * Most Common Fracture Site: The vertebral body (compression fractures) is the most common site, followed by the hip and distal radius (Colles’ fracture) [2]. * Biochemical Profile: In primary osteoporosis, serum Calcium, Phosphate, and PTH levels are typically normal. * Gold Standard Investigation: Dual-energy X-ray absorptiometry (DEXA).

Q: A 68-year-old patient, postoperative from thyroidectomy, presents with muscle cramps. Chvostek's and Trousseau's signs are noted on examination. What is the most likely finding on electrocardiogram?

Prolonged QT interval. ### Explanation **Correct Answer: A. Prolonged QT interval** **Concept:** The patient is presenting with signs of **hypocalcemia** (muscle cramps, Chvostek's sign, and Trousseau's sign) following a thyroidectomy. This is a classic complication caused by accidental removal or devascularization of the parathyroid glands, leading to **Hypoparathyroidism** [1]. Calcium ions play a critical role in the ventricular action potential. In hypocalcemia, there is a **prolongation of Phase 2 (the plateau phase)** of the action potential. Since the QT interval represents the total duration of ventricular depolarization and repolarization, a lengthened plateau phase manifests on the ECG as a **prolonged QT interval** [1]. **Analysis of Incorrect Options:** * **B. Short QT interval:** This is a characteristic finding in **Hypercalcemia**. High calcium levels shorten the plateau phase of the action potential. * **C & D. ST elevation/depression:** These are typically associated with myocardial ischemia, infarction, or electrolyte imbalances like hyperkalemia (ST depression), but are not the primary or classic findings of isolated hypocalcemia. **NEET-PG High-Yield Pearls:** * **Chvostek’s Sign:** Tapping the facial nerve (anterior to the ear) causes twitching of facial muscles. * **Trousseau’s Sign:** Carpal spasm induced by inflating a BP cuff above systolic pressure for 3 minutes (more sensitive than Chvostek’s). * **ECG in Hypocalcemia:** Specifically, it is the **ST segment** that prolongs, leading to a long QT [1]. The T-wave usually remains normal. * **Danger:** A prolonged QT interval can predispose patients to **Torsades de Pointes** (a form of polymorphic ventricular tachycardia) [2]. * **Management:** Acute symptomatic hypocalcemia is treated with **IV Calcium Gluconate**.

Q: All of the following statements about Pseudohypoparathyroidism are true, except?

Decreased serum PTH. **Explanation:** **Pseudohypoparathyroidism (PHP)** is a group of disorders characterized by **target organ resistance to Parathyroid Hormone (PTH)**. The underlying defect is typically a mutation in the *GNAS1* gene, which encodes the alpha subunit of the stimulatory G protein (Gsα) required for PTH signaling [1]. 1. **Why Option A is the Correct Answer (The "Except"):** In PHP, the body is resistant to PTH. Because the kidneys and bones do not respond to the hormone, the body perceives a deficiency. In an attempt to compensate, the parathyroid glands become hyperactive, leading to **Increased serum PTH** (Secondary Hyperparathyroidism). Therefore, "Decreased serum PTH" is incorrect and is the right choice for this "except" question. 2. **Analysis of Other Options:** * **Option B (Decreased serum calcium):** Since the kidneys cannot respond to PTH, there is decreased renal calcium reabsorption and impaired Vitamin D activation, leading to hypocalcemia [1]. * **Option C (Increased serum phosphate):** PTH normally promotes phosphate excretion (phosphaturia) [2]. Resistance to PTH leads to phosphate retention, resulting in hyperphosphatemia [1]. * **Option D (Albright's hereditary osteodystrophy):** This is the classic phenotypic presentation of PHP Type 1a, characterized by short stature, round face, obesity, and brachydactyly (shortening of the 4th and 5th metacarpals) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Pseudopseudohypoparathyroidism (PPHP):** Patients have the physical features of Albright's (AHO) but have **normal** biochemical levels (Normal Ca, PO4, and PTH) because the defect is inherited paternally [1]. * **Ellsworth-Howard Test:** Historically used to differentiate Hypoparathyroidism from PHP. In PHP, administration of exogenous PTH fails to increase urinary cAMP or phosphate. * **Short 4th Metacarpal:** Also known as **Archibald’s sign**, a classic radiological finding in AHO.

Q: Which of the following is true for Klinefelter's syndrome?

Increased arm span and height. Explanation: **Klinefelter’s Syndrome (47,XXY)** is the most common sex chromosome disorder causing primary hypogonadism in males. **Why Option B is Correct:** Patients with Klinefelter’s syndrome exhibit **eunuchoid body proportions** [1]. This occurs because the deficiency in testosterone leads to delayed closure of the epiphyseal plates. Growth continues under the influence of growth hormone, specifically affecting the long bones. Consequently, the **arm span exceeds the total height** (usually by >2 cm), and the lower segment (pubis to floor) is longer than the upper segment (crown to pubis) [1]. **Analysis of Incorrect Options:** * **A (45,X):** This is the karyotype for **Turner Syndrome**, which presents in phenotypic females with short stature and streak ovaries [3, 5]. Klinefelter’s is typically **47,XXY**. * **C (Attains puberty normally):** While initial pubertal changes may begin, patients fail to complete maturation. They develop **hypergonadotropic hypogonadism** due to testicular failure, leading to poor development of secondary sexual characteristics [1, 4]. * **D (Normal testes and genitalia):** A hallmark of Klinefelter’s is **small, firm testes** (usually <2 cm or <6 mL volume) due to hyalinization and fibrosis of the seminiferous tubules [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Laboratory Findings:** Low Testosterone, **Increased LH and FSH** (due to loss of feedback inhibition), and Increased Estradiol [1]. * **Clinical Features:** Gynecomastia (increased risk of male breast cancer), infertility (azoospermia), and mild intellectual disability [1, 4]. * **Histology:** Absence of germ cells and **Leydig cell hyperplasia** (clumping). * **Barr Body:** Positive (due to the extra X chromosome).

Q: Which of the following is NOT a feature of Kallmann syndrome?

Mental retardation. **Explanation:** **Kallmann Syndrome** is a form of **hypogonadotropic hypogonadism** (low FSH/LH) associated with **anosmia** (loss of smell). It results from the failure of GnRH-secreting neurons and olfactory neurons to migrate from the olfactory placode to the hypothalamus during development. **Why Mental Retardation is the Correct Answer:** Mental retardation is **not** a characteristic feature of Kallmann syndrome. While the condition involves developmental migration defects, cognitive function is typically preserved. If a patient presents with hypogonadotropic hypogonadism and mental retardation, clinicians should consider other syndromes like **Prader-Willi Syndrome** or **Laurence-Moon-Biedl Syndrome**. **Analysis of Incorrect Options:** * **Micropenis (A):** Due to low testosterone levels during the critical period of fetal development, males often present with a micropenis and cryptorchidism. * **Primary Amenorrhea (B):** In females, the lack of GnRH leads to low estrogen levels and a failure to initiate puberty, resulting in primary amenorrhea and absent secondary sexual characteristics. * **Mirror Movements (C):** Also known as **bimanual synkinesis**, these are involuntary movements of one hand that mimic the voluntary movements of the other. This is a recognized neurological association in Kallmann syndrome (often linked to *KAL1* gene mutations). **High-Yield Clinical Pearls for NEET-PG:** 1. **Inheritance:** Most commonly X-linked recessive (*KAL1* gene), but can be Autosomal Dominant (*FGFR1*) or Autosomal Recessive. 2. **Key Triad:** Hypogonadotropic hypogonadism + Anosmia/Hyposmia + Midline defects. 3. **Associated Features:** Renal agenesis (unilateral), cleft lip/palate, and sensorineural deafness. 4. **Diagnosis:** Low Testosterone/Estrogen with low or inappropriately normal FSH/LH; MRI may show absent/hypoplastic olfactory bulbs.

Q: Weight gain is seen in all of the following conditions except?

Pheochromocytoma. The correct answer is **Pheochromocytoma**. This condition is characterized by the hypersecretion of catecholamines (epinephrine and norepinephrine), which leads to a **hypermetabolic state**. Catecholamines stimulate glycogenolysis and lipolysis, significantly increasing the basal metabolic rate (BMR) [1]. Consequently, patients typically present with **weight loss** [2] despite a normal or increased appetite, alongside the classic triad of episodic headaches, sweating, and palpitations [2]. **Analysis of Incorrect Options:** * **Cushing’s Syndrome:** Excess cortisol leads to increased gluconeogenesis and adipogenesis. It causes characteristic **centripetal obesity** (moon facies, buffalo hump, and truncal weight gain) [2] due to the redistribution of fat. * **Hypothyroidism:** A deficiency in thyroid hormones leads to a **decreased BMR**. Weight gain in hypothyroidism [2] is common but usually modest, resulting from both fat accumulation and fluid retention (myxedema/glycosaminoglycan deposition). * **Insulinoma:** This neuroendocrine tumor secretes excessive insulin, leading to recurrent hypoglycemia. Patients often experience weight gain because they **overeat (hyperphagia)** to prevent or treat hypoglycemic symptoms, and insulin itself is a potent anabolic/lipogenic hormone. **NEET-PG High-Yield Pearls:** * **Pheochromocytoma Rule of 10s:** 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paragangliomas), and 10% familial. * **MEN 2A/2B:** Always screen for Pheochromocytoma before performing surgery for Medullary Thyroid Carcinoma. * **Differential for Weight Loss with Increased Appetite:** Hyperthyroidism, Diabetes Mellitus (Type 1), Pheochromocytoma, and Malabsorption syndromes.

Question 1

All of the following are true about Graves disease except?

Accepted Answer

Remissions and exacerbations are not infrequent.

Answer

Cardiac failure is common.

Answer

Hypertrophy and hyperplasia of the thyroid gland are due to TSH receptor antibodies.

Answer

It is highly vascular with audible bruit.

Question 2

Which of the following statements is not true regarding Hashimoto's thyroiditis?

Accepted Answer

Presents after 6-8 weeks of upper respiratory tract infection

Answer

More common in females

Answer

HLA-B8 association

Answer

Can lead to thyroid lymphoma

Question 3

What laboratory test is most appropriate for this patient?

Accepted Answer

Calcitonin

Answer

Alpha-fetoprotein

Answer

Beta2-microglobulin

Answer

Insulin-like growth factor-1

Question 4

In osteoporosis, what change occurs?

Accepted Answer

Decrease in absolute amount of bone mass

Answer

More common in males

Answer

Radiographs show normal bone density

Answer

Hormonal replacement therapy

Question 5

A 68-year-old patient, postoperative from thyroidectomy, presents with muscle cramps. Chvostek's and Trousseau's signs are noted on examination. What is the most likely finding on electrocardiogram?

Accepted Answer

Prolonged QT interval

Answer

Short QT interval

Answer

ST elevation

Answer

ST depression

Question 6

All of the following statements about Pseudohypoparathyroidism are true, except?

Accepted Answer

Decreased serum PTH

Answer

Decreased serum calcium

Answer

Increased serum phosphate

Answer

Albright's hereditary osteodystrophy

Question 7

Which of the following is true for Klinefelter's syndrome?

Accepted Answer

Increased arm span and height

Answer

45,X

Answer

Attains puberty normally

Answer

Normal testes and genitalia

Question 8

Which of the following is NOT a feature of Kallmann syndrome?

Accepted Answer

Mental retardation

Answer

Micropenis

Answer

Primary amenorrhea

Answer

Mirror movements of the hands

Question 9

All of the following are helpful in the initial treatment of severe hypercalcemia associated with hyperparathyroidism except?

Accepted Answer

Glucocorticoids

Answer

Hydration with saline

Answer

Forced diuresis with loop diuretics

Answer

Pamidronate

Question 10

Weight gain is seen in all of the following conditions except?

Accepted Answer

Pheochromocytoma

Answer

Cushing's syndrome

Answer

Hypothyroidism

Answer

Insulinoma

Endocrinology — MCQs

Endocrinology — MCQs

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