Endocrinology Practice Questions

Q: Osteoporosis is caused by all of the following except?

Estradiol. The correct answer is **Estradiol**. Osteoporosis is a skeletal disorder characterized by low bone mass and micro-architectural deterioration [1]. To answer this question, one must distinguish between drugs that cause bone loss (osteoporotic agents) and those that are bone-protective. **Why Estradiol is the correct answer:** Estradiol (Estrogen) is **protective** against osteoporosis [3]. It inhibits bone resorption by decreasing the activity and lifespan of osteoclasts while promoting osteoblast survival. In postmenopausal women, the decline in estradiol levels is the primary driver of accelerated bone loss [3]. Therefore, estradiol is a treatment modality (Hormone Replacement Therapy), not a cause of the disease. **Why the other options are incorrect:** * **Glucocorticoids:** These are the most common cause of drug-induced osteoporosis [1]. They decrease osteoblast function, reduce intestinal calcium absorption, and increase renal calcium excretion [1]. * **Heparin:** Long-term use of unfractionated heparin (UFH) stimulates osteoclasts and inhibits osteoblasts, leading to decreased bone density. * **Methotrexate:** Used in high doses (e.g., in oncology), it is directly toxic to osteoblasts and triggers "methotrexate osteopathy," characterized by bone pain and fractures. **High-Yield Clinical Pearls for NEET-PG:** 1. **Other Drugs causing Osteoporosis:** Proton Pump Inhibitors (PPIs), Anticonvulsants (Phenytoin/Phenobarbital), Thiazolidinediones (Pioglitazone) [2], and Aromatase Inhibitors [2]. 2. **Gold Standard Diagnosis:** DEXA Scan (Dual-energy X-ray Absorptiometry). Osteoporosis is defined as a **T-score ≤ -2.5**. 3. **First-line Treatment:** Bisphosphonates (e.g., Alendronate), which act by inhibiting osteoclast-mediated bone resorption.

Q: A 54-year-old obese man diagnosed with NIDDM one year ago is on glipizide and metformin. He also takes propranolol and nifedipine for hypertension, and recently started naproxen for severe osteoarthritis. His current BP is 154/92. His BUN is 29 mg/dL and creatinine is 1.8 mg/dL, both of which were normal one year prior. Which medication is most likely responsible for the increase in BUN and creatinine?

Naproxen. ### Explanation The correct answer is **Naproxen**. #### 1. Why Naproxen is the Correct Answer Naproxen is a Non-Steroidal Anti-Inflammatory Drug (NSAID) [1]. NSAIDs inhibit the enzyme cyclooxygenase (COX), leading to decreased synthesis of **prostaglandins** (specifically PGE2 and PGI2). In the kidneys, prostaglandins are essential for maintaining renal blood flow by causing **vasodilation of the afferent arteriole** [1]. In patients with underlying risk factors (diabetes, hypertension, or older age), the inhibition of these vasodilatory prostaglandins leads to afferent arteriolar vasoconstriction. This reduces the glomerular filtration rate (GFR), resulting in **Prerenal Azotemia**, characterized by an increase in Blood Urea Nitrogen (BUN) and Creatinine. #### 2. Why the Other Options are Incorrect * **Glipizide (Sulfonylurea):** Primarily causes hypoglycemia and weight gain; it does not have direct nephrotoxic effects. * **Metformin (Biguanide):** While metformin must be dose-adjusted or discontinued in renal failure to prevent **lactic acidosis**, it does not *cause* the rise in creatinine itself. * **Nifedipine (Calcium Channel Blocker):** CCBs are generally neutral or protective regarding renal hemodynamics and do not cause acute elevations in BUN/Creatinine. #### 3. NEET-PG High-Yield Pearls * **Triple Whammy:** Be cautious of the "Triple Whammy" effect on the kidney: **NSAIDs** (constrict afferent arteriole) + **ACE inhibitors/ARBs** (dilate efferent arteriole) + **Diuretics** (reduce plasma volume). This combination significantly increases the risk of Acute Kidney Injury (AKI). * **Analgesic Nephropathy:** Chronic use of NSAIDs can lead to **Chronic Interstitial Nephritis** and **Renal Papillary Necrosis** [1]. * **Metformin Guideline:** In NEET-PG, remember that Metformin is contraindicated if the eGFR is <30 mL/min/1.73m² due to the risk of lactic acidosis.

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].

Q: Which of the following is NOT a feature of hypothyroidism?

Increased risk of infections. Hypothyroidism is characterized by a generalized slowing of metabolic processes. The correct answer is **Option D (Increased risk of infections)** because, unlike Diabetes Mellitus or Cushing’s syndrome, hypothyroidism is not typically associated with impaired immunity or a significantly increased risk of infections. **Why the other options are features of Hypothyroidism:** * **Obesity (Option A):** A decrease in the Basal Metabolic Rate (BMR) leads to weight gain [2]. This is primarily due to fluid retention (accumulation of glycosaminoglycans) and decreased thermogenesis, rather than just fat accumulation. * **Hypertension (Option B):** While hyperthyroidism causes systolic hypertension, hypothyroidism often causes **diastolic hypertension**. This occurs due to increased systemic vascular resistance and arterial stiffness. * **High TSH levels (Option C):** In primary hypothyroidism (the most common form), the loss of negative feedback from low T4/T3 levels leads the pituitary to secrete compensatory high levels of TSH [3]. **Clinical Pearls for NEET-PG:** * **Wolff-Chaikoff Effect:** Hypothyroidism induced by excessive iodine ingestion (e.g., amiodarone). * **Myxedema Coma:** The most severe form of hypothyroidism, presenting with hypothermia, bradycardia, and altered sensorium. * **Dyslipidemia:** Hypothyroidism is a common secondary cause of hypercholesterolemia (due to decreased LDL receptor expression [1]). * **Anemia:** Most commonly normocytic normochromic, but can be macrocystic (if associated with Pernicious Anemia in Schmidt’s Syndrome).

Q: In which of the following conditions would the patient most likely be normotensive?

Bartter syndrome. **Explanation:** The correct answer is **Bartter syndrome**. This condition is a rare autosomal recessive renal tubular disorder characterized by defective salt reabsorption in the thick ascending limb of the loop of Henle. This leads to salt wasting, which triggers the Renin-Angiotensin-Aldosterone System (RAAS). While aldosterone levels are high (secondary hyperaldosteronism), the patient remains **normotensive or hypotensive** because the primary defect is volume depletion due to salt loss. **Analysis of Options:** * **Primary Hyperparathyroidism:** Approximately 20–40% of these patients have hypertension [1]. The mechanism is multifactorial, involving hypercalcemia-induced increase in peripheral vascular resistance and potential renal impairment. * **Hypothyroidism:** Often associated with **diastolic hypertension**. This occurs due to increased peripheral vascular resistance and low-turnover states despite a decrease in cardiac output. * **Cushing Syndrome:** Hypertension is present in over 80% of cases. It is caused by increased mineralocorticoid activity of cortisol, enhanced sensitivity to catecholamines, and activation of the RAAS. **High-Yield Clinical Pearls for NEET-PG:** * **Bartter vs. Gitelman:** Bartter syndrome presents early in life with polyuria and growth retardation (mimics Loop diuretics). Gitelman syndrome presents later with prominent hypomagnesemia and hypocalciuria (mimics Thiazides). * **Key Triad of Bartter:** Hypokalemia, Metabolic Alkalosis, and **Normotension** (despite high renin/aldosterone). * **Differential Diagnosis:** If a patient has hypokalemia, metabolic alkalosis, and **hypertension**, think of Conn’s syndrome (Primary Hyperaldosteronism) or Liddle syndrome.

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

Bromocriptine. **Explanation:** The clinical presentation of secondary amenorrhea and galactorrhea in a young woman, combined with an MRI showing a pituitary tumor <10 mm (Microadenoma), is classic for a **Prolactinoma**. [1] **1. Why Bromocriptine is Correct:** Prolactinomas are unique among pituitary tumors because **medical management is the first-line treatment**, regardless of size. [1] Dopamine agonists like **Bromocriptine** or Cabergoline act on D2 receptors in the pituitary to inhibit prolactin secretion and shrink the tumor mass. [1] They effectively restore menses, stop galactorrhea, and achieve tumor shrinkage in over 80% of patients. **2. Why Incorrect Options are Wrong:** * **Hormonal therapy (Option A):** While OCPs can induce withdrawal bleeding, they do not address the underlying hyperprolactinemia or the pituitary tumor. In fact, estrogen can theoretically stimulate lactotroph hyperplasia. * **Radiotherapy (Option B):** This is reserved for refractory cases or aggressive macroadenomas that fail both medical and surgical therapy due to long-term risks like hypopituitarism. * **Chemotherapy (Option C):** Cytotoxic chemotherapy is not used for benign pituitary adenomas. Temozolomide is only considered for rare, malignant pituitary carcinomas. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice:** While Bromocriptine is the traditional answer, **Cabergoline** is now preferred in clinical practice due to higher efficacy and better tolerability (longer half-life). * **Micro vs. Macro:** Microadenomas are <10 mm; Macroadenomas are ≥10 mm. [1] * **Surgery (Transsphenoidal):** Indicated only if the patient is intolerant to dopamine agonists or if the tumor is resistant to medical therapy. * **Hook Effect:** In very large macroadenomas, extremely high prolactin levels can cause a false low reading in lab assays; serial dilution is required for diagnosis.

Question 1

Osteoporosis is caused by all of the following except?

Accepted Answer

Estradiol

Answer

Methotrexate

Answer

Glucocorticoids

Answer

Heparin

Question 2

Nephrocalcinosis is associated with all of the following, except?

Accepted Answer

Hypoparathyroidism

Answer

Multiple myeloma

Answer

Milk-alkali syndrome

Answer

Hyperparathyroidism

Question 3

A 54-year-old obese man diagnosed with NIDDM one year ago is on glipizide and metformin. He also takes propranolol and nifedipine for hypertension, and recently started naproxen for severe osteoarthritis. His current BP is 154/92. His BUN is 29 mg/dL and creatinine is 1.8 mg/dL, both of which were normal one year prior. Which medication is most likely responsible for the increase in BUN and creatinine?

Accepted Answer

Naproxen

Answer

Glipizide

Answer

Metformin

Answer

Nifedipine

Question 4

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 5

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 6

Primary hypothyroidism is seen in all EXCEPT?

Accepted Answer

Bexarotene

Answer

Iodine deficiency

Answer

Iodine excess

Answer

Lithium

Question 7

Which of the following is NOT a feature of hypothyroidism?

Accepted Answer

Increased risk of infections

Answer

Obesity

Answer

Hypertension

Answer

High TSH levels

Question 8

In which of the following conditions would the patient most likely be normotensive?

Accepted Answer

Bartter syndrome

Answer

Primary hyperparathyroidism

Answer

Hypothyroidism

Answer

Cushing syndrome

Question 9

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

Accepted Answer

Bromocriptine

Answer

Hormonal therapy for withdrawal bleeding

Answer

Radiotherapy

Answer

Chemotherapy

Question 10

A 49-year-old female presents with a non-healing ulcer on the right medial malleolus. On examination, there is symmetrical loss of sensation in both extremities. She also complains of recurrent vaginal discharge and irregular menstrual cycles. She reports experiencing hot flashes. What is the most likely pathological finding to be seen in her peripheral nerves?

Accepted Answer

Axonal neuropathy

Answer

Acute inflammation

Answer

Wallerian degeneration

Answer

Lymphocytic infiltration in the endoneurium

Endocrinology — MCQs

Endocrinology — MCQs

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