Endocrinology Practice Questions

Q: Which of the following is NOT used in the management of thyroid storm?

Radioactive iodine. **Explanation:** **Thyroid storm** is a life-threatening medical emergency characterized by extreme hypermetabolism. The management goal is to rapidly inhibit thyroid hormone synthesis, release, and peripheral conversion, while stabilizing systemic symptoms. **Why Radioactive Iodine (RAI) is NOT used:** Radioactive iodine (I-131) is contraindicated in the acute management of thyroid storm. Its mechanism involves the destruction of thyroid parenchyma via beta-radiation, which takes **weeks to months** to achieve an euthyroid state. Crucially, RAI can initially cause a transient release of stored thyroid hormones due to radiation-induced thyroiditis, which would **exacerbate** a thyroid storm and potentially lead to cardiovascular collapse. **Why the other options are used:** * **Propylthiouracil (PTU):** The preferred antithyroid drug in storm because it inhibits both the synthesis of hormones (via TPO inhibition) and the **peripheral conversion of T4 to T3**. * **Potassium Iodide (Lugol’s iodine/SSKI):** Administered to inhibit the *release* of stored hormones (the **Wolff-Chaikoff effect**). *Note: It must be given at least 1 hour after PTU to prevent the iodine from being used as a substrate for new hormone synthesis (Jod-Basedow effect).* * **Glucocorticoids (e.g., Dexamethasone):** These are used to inhibit the peripheral conversion of T4 to T3 and to treat potential relative adrenal insufficiency associated with severe thyrotoxicosis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Beta-blockers:** Propranolol is the drug of choice to control sympathetic overactivity and further inhibit T4 to T3 conversion. 2. **Sequence of Treatment:** 1. Beta-blocker → 2. PTU → 3. Iodine (1 hour later) → 4. Steroids. 3. **Bile acid sequestrants (Cholestyramine):** Can be used as an adjunct to decrease the enterohepatic circulation of thyroid hormones.

Q: A progressive increase in mandibular length and in mandibular interdental spacing in an adult patient is characteristic of which condition?

Hyperpituitarism. The clinical presentation described—progressive increase in mandibular length (**prognathism**) and widening of spaces between the teeth (**diastema**) in an adult—is a classic hallmark of **Acromegaly**, which results from **Hyperpituitarism** (specifically, a growth hormone-secreting adenoma) [1]. **Why Hyperpituitarism is correct:** In adults, after the epiphyseal plates have fused, excess Growth Hormone (GH) cannot increase height but instead causes **acral overgrowth** and soft tissue hypertrophy [1]. The mandible is particularly sensitive; its enlargement leads to a "lantern jaw" appearance. As the bone expands, the fixed number of teeth become separated, leading to increased interdental spacing. **Why the other options are incorrect:** * **Periodontosis:** While this can cause tooth mobility and spacing due to bone loss, it does not cause an increase in mandibular length or systemic bony overgrowth. * **Hypothyroidism:** In adults (Myxedema), this typically presents with macroglossia (enlarged tongue) and non-pitting edema, but it does not cause bony enlargement of the jaw. * **Hypoadrenalism (Addison’s Disease):** This is characterized by hyperpigmentation, hypotension, and electrolyte imbalances, with no effect on bone growth or dental spacing [3]. **NEET-PG High-Yield Pearls:** * **Best Initial Test:** Serum IGF-1 levels (more stable than GH) [2]. * **Gold Standard Diagnostic Test:** Oral Glucose Tolerance Test (OGTT) showing failure to suppress GH levels below 1 ng/mL [2]. * **Most Common Cause:** Somatotroph adenoma of the anterior pituitary [4]. * **Associated Comorbidities:** Sleep apnea, bitemporal hemianopia (due to optic chiasm compression), and increased risk of colorectal polyps/carcinoma [2].

Q: Which of the following is not seen in thyrotoxicosis?

Menorrhagia. **Explanation:** In thyrotoxicosis, the excess of circulating thyroid hormones (T3 and T4) leads to a hypermetabolic state and increased sympathetic activity [1]. **Why Menorrhagia is the correct answer:** Thyrotoxicosis typically causes **Oligomenorrhea** (infrequent periods) or **Amenorrhea** (absence of periods), rather than Menorrhagia. This occurs because high thyroid hormone levels interfere with the hypothalamic-pituitary-ovarian axis, leading to anovulatory cycles and decreased estrogen levels. Conversely, **Menorrhagia** (heavy menstrual bleeding) is a classic hallmark of **Hypothyroidism**, where low thyroid levels lead to impaired coagulation factors and failure of LH surge. **Why the other options are incorrect:** * **Palpitations:** Thyroid hormones increase the expression of beta-adrenergic receptors in the heart, leading to increased heart rate (tachycardia) and contractility [3]. * **Anxiety:** Excess T3/T4 has a stimulatory effect on the central nervous system, commonly manifesting as irritability, nervousness, and anxiety [1]. * **Weight loss:** Despite an increased appetite (polyphagia), the basal metabolic rate (BMR) is significantly elevated, leading to the breakdown of fat and muscle stores, resulting in weight loss [1], [3]. **Clinical Pearls for NEET-PG:** * **Most common cause of thyrotoxicosis:** Graves’ Disease (associated with exophthalmos and pretibial myxedema) [1]. * **Cardiac sign:** "Apathetic hyperthyroidism" in the elderly may present only with Atrial Fibrillation [2]. * **Reflexes:** Look for "brisk" or hyperreflexia in thyrotoxicosis, whereas "hung-up" (delayed relaxation) DTRs are seen in hypothyroidism. * **Tremors:** Characteristically fine, high-frequency tremors are seen in hyperthyroidism [1].

Q: A patient presents with thin limbs, central obesity, fat cheeks, a ruddy complexion, and an elevated blood glucose level. What is the most likely diagnosis?

Cushing syndrome due to an adrenal tumor.. ### Explanation **Correct Answer: D. Cushing syndrome due to an adrenal tumor.** The clinical presentation described—**central obesity, thin limbs** (due to muscle wasting), **fat cheeks** (moon facies), and a **ruddy complexion** (plethora)—is classic for **Cushing Syndrome** [1]. These features result from chronic hypercortisolism. Cortisol promotes gluconeogenesis and insulin resistance, leading to the **elevated blood glucose levels** (secondary diabetes) seen in this patient. An adrenal tumor is a primary cause of ACTH-independent Cushing syndrome [2]. **Why other options are incorrect:** * **Option A:** Renal artery stenosis leads to secondary hyperaldosteronism. While it causes hypertension and hypokalemia, it does not cause the fat redistribution or hyperglycemia characteristic of cortisol excess. * **Option B:** Hyperprolactinemia typically presents with galactorrhea, amenorrhea, or infertility. It does not cause central obesity or the specific physical signs mentioned. * **Option C:** Acromegaly presents with enlargement of hands/feet, frontal bossing, and prognathism. While it can cause hyperglycemia (GH is counter-regulatory), it does not cause the "moon facies" or "thin limbs" pattern of Cushing syndrome. **NEET-PG High-Yield Pearls:** * **Screening Tests for Cushing:** 24-hour urinary free cortisol, Low-Dose Dexamethasone Suppression Test (LDDST), or late-night salivary cortisol [3]. * **Muscle Wasting:** Cortisol causes protein catabolism, specifically affecting proximal muscles (leading to thin limbs) [1]. * **Striae:** Look for "purple/violaceous striae" (>1 cm wide) in exam vignettes; these are pathognomonic for Cushing syndrome. * **Hypertension:** Cortisol has weak mineralocorticoid activity and increases sensitivity to catecholamines, leading to high BP.

Q: A 39-year-old woman presents with weight gain, abnormal menstrual cycles, depression, and weakness. Physical examination reveals multiple purplish striae on the abdomen and bruises over the lower extremities. Laboratory studies show normal thyroid-stimulating hormone and thyroid hormone levels, along with elevated cortisol secretion. If the patient has adrenal hyperfunction, which of the following findings may also be present?

Hirsutism. **Explanation:** The clinical presentation of weight gain, purple striae, bruising, and weakness, combined with elevated cortisol, is diagnostic of **Cushing’s Syndrome** [1]. **1. Why Hirsutism is Correct:** In cases of adrenal hyperfunction (specifically ACTH-dependent Cushing’s disease or adrenal carcinomas), there is a simultaneous overproduction of **adrenal androgens** (such as DHEA-S) along with cortisol. These androgens lead to virilization signs, including **hirsutism** (excessive male-pattern hair growth), acne, and menstrual irregularities [1]. Even in ACTH-independent cases like adrenal adenomas, the high levels of cortisol can sometimes cross-react with androgen receptors or be associated with mild androgen excess. **2. Why the Other Options are Incorrect:** * **Enhanced glucose uptake (A) & Hypoglycemia (D):** Cortisol is a "stress hormone" that antagonizes insulin. It stimulates gluconeogenesis and inhibits peripheral glucose uptake, leading to **hyperglycemia** and secondary diabetes mellitus, not hypoglycemia. * **Hypocalciuria (C):** Glucocorticoids inhibit calcium reabsorption in the renal tubules and decrease intestinal calcium absorption. This leads to **hypercalciuria**, which increases the risk of nephrolithiasis (kidney stones). **Clinical Pearls for NEET-PG:** * **Proximal Myopathy:** The "weakness" in Cushing’s is due to cortisol-induced muscle catabolism, typically affecting the proximal limbs [1]. * **Screening Tests:** The best initial tests are the 24-hour urinary free cortisol, late-night salivary cortisol, or the Low-Dose Dexamethasone Suppression Test (LDDST) [2]. * **Hypokalemia:** Severe hypercortisolism (often from ectopic ACTH) can cause mineralocorticoid effects, leading to hypokalemic metabolic alkalosis.

Question 1

Which of the following is the most likely clinical feature associated with high prolactin levels causing sexual dysfunction?

Accepted Answer

Failure of erection with absent nocturnal penile tumescence (NPT)

Answer

Loss of sexual desire

Answer

Absence of emission

Answer

Absence of orgasm with normal libido and erectile function

Question 2

A 45-year-old woman presents with a severe sore throat. Physical examination reveals fever and an extremely tender, enlarged thyroid gland, with no throat erythema. Serum thyroid studies demonstrate mild hyperthyroidism. Two months later, the patient is asymptomatic, and thyroid function tests have returned to normal. She never again experiences difficulty with her thyroid function. Which of the following was the most likely cause of her hyperthyroidism?

Accepted Answer

Subacute granulomatous thyroiditis

Answer

Diffuse nontoxic goiter

Answer

Graves disease

Answer

Hashimoto's thyroiditis

Question 3

Which of the following is NOT used in the management of thyroid storm?

Accepted Answer

Radioactive iodine

Answer

Glucocorticoids

Answer

Potassium iodide

Answer

Propylthiouracil

Question 4

A progressive increase in mandibular length and in mandibular interdental spacing in an adult patient is characteristic of which condition?

Accepted Answer

Hyperpituitarism

Answer

Periodontosis

Answer

Hypothyroidism

Answer

Hypoadrenalism

Question 5

Which of the following is true about Cushing's syndrome?

Accepted Answer

Bronchial and mediastinal carcinoids can cause Cushing's syndrome.

Answer

Adrenomedullary hyperplasia in association with MEN syndrome is a common cause.

Answer

It is diagnosed by hypokalemia in association with increased adrenal secretion.

Answer

It is often fatal due to coronary and cerebrovascular accidents.

Question 6

Which of the following is not seen in thyrotoxicosis?

Accepted Answer

Menorrhagia

Answer

Palpitations

Answer

Anxiety

Answer

Weight loss

Question 7

In type 2 DM, increased fasting plasma glucose is predominantly due to which of the following?

Accepted Answer

Increased hepatic glucose output

Answer

Decreased peripheral utilization of glucose

Answer

Decreased insulin secretion

Answer

Decreased transport of glucose to tissues

Question 8

A patient presents with thin limbs, central obesity, fat cheeks, a ruddy complexion, and an elevated blood glucose level. What is the most likely diagnosis?

Accepted Answer

Cushing syndrome due to an adrenal tumor.

Answer

Elevated blood levels of aldosterone and renin resulting from an atherosclerotic plaque in a renal artery.

Answer

Hyperprolactinemia due to a pituitary tumor.

Answer

Acromegaly due to a GH-producing tumor that developed in adulthood.

Question 9

A 63-year-old woman presents with a 6-month history of recurrent epigastric pain and nausea. Abdominal ultrasound reveals a 13-mm hypoechoic lesion in the tail of the pancreas. Physical examination shows flushing of the face, periorbital edema, and hypotension. Laboratory studies disclose normal serum levels of gastrin, amylase, insulin, and vasoactive intestinal polypeptide. Urinalysis demonstrates elevated levels of metanephrines. Which of the following is the most likely diagnosis?

Accepted Answer

Pancreatic carcinoid

Answer

Adenocarcinoma of pancreas

Answer

Glucagonoma

Answer

Insulinoma

Question 10

A 39-year-old woman presents with weight gain, abnormal menstrual cycles, depression, and weakness. Physical examination reveals multiple purplish striae on the abdomen and bruises over the lower extremities. Laboratory studies show normal thyroid-stimulating hormone and thyroid hormone levels, along with elevated cortisol secretion. If the patient has adrenal hyperfunction, which of the following findings may also be present?

Accepted Answer

Hirsutism

Answer

Enhanced glucose uptake

Answer

Hypocalciuria

Answer

Hypoglycemia

Endocrinology — MCQs

Endocrinology — MCQs

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