Endocrinology Practice Questions

Q: Which of the following is associated with secondary hyperparathyroidism?

Chronic renal failure. **Explanation:** **1. Why Chronic Renal Failure (CRF) is correct:** Secondary hyperparathyroidism is a compensatory hypersecretion of Parathyroid Hormone (PTH) in response to prolonged **hypocalcemia** [1]. In Chronic Renal Failure, two main mechanisms trigger this [2]: * **Hyperphosphatemia:** Failing kidneys cannot excrete phosphate. High phosphate levels directly stimulate PTH and bind ionized calcium [3]. * **Vitamin D Deficiency:** The kidneys fail to convert 25-OH Vitamin D into its active form, **1,25-(OH)₂ Vitamin D (Calcitriol)**. This leads to decreased intestinal calcium absorption [1], [5]. The parathyroid glands undergo diffuse hyperplasia to secrete more PTH in an attempt to normalize serum calcium levels [2]. **2. Why the other options are incorrect:** * **A. Parathyroid Adenoma:** This is the most common cause of **Primary** hyperparathyroidism, where the gland autonomously overproduces PTH regardless of calcium levels [1], [4]. * **B. Marked Hypercalcemia:** Secondary hyperparathyroidism is characterized by **low or low-normal calcium** [3]. If calcium becomes high in a patient with long-standing secondary hyperparathyroidism, it suggests progression to **Tertiary hyperparathyroidism** (autonomous secretion) [2]. * **D. Parathyroidectomy:** This is the definitive treatment for Primary or Tertiary hyperparathyroidism [4]. In Secondary hyperparathyroidism, the management focuses on treating the underlying cause (e.g., phosphate binders, Vitamin D analogues, or cinacalcet). **3. High-Yield Clinical Pearls for NEET-PG:** * **Primary Hyperparathyroidism:** High PTH, High Calcium, Low Phosphate [1]. * **Secondary Hyperparathyroidism:** High PTH, **Low/Normal Calcium**, High Phosphate (in CRF) [3]. * **Tertiary Hyperparathyroidism:** Very High PTH, **High Calcium** (seen after long-term CRF or post-renal transplant) [2]. * **Radiological Hallmark:** Subperiosteal bone resorption (most common in the phalanges).

Q: Which of the following is a risk factor for developing Type 1 Diabetes mellitus?

HLA DR3. **Explanation:** Type 1 Diabetes Mellitus (T1DM) is an autoimmune disorder characterized by the destruction of pancreatic beta cells, leading to absolute insulin deficiency [1]. The primary risk factors are genetic susceptibility and environmental triggers [2]. **Why HLA DR3 is correct:** The strongest genetic association for T1DM lies within the **Major Histocompatibility Complex (MHC) Class II** genes on chromosome 6 [3]. Specifically, **HLA-DR3** and **HLA-DR4** are the most significant risk alleles. Approximately 90% of children with T1DM carry one or both of these alleles. Inheriting both (DR3/DR4 heterozygosity) confers the highest risk. These HLA molecules are involved in presenting antigens to T-cells; specific polymorphisms lead to the failure of self-tolerance and the subsequent autoimmune attack on islet cells. **Why other options are incorrect:** * **Male Gender:** T1DM does not show a strong gender predilection; it affects males and females almost equally (unlike many other autoimmune diseases which are female-dominant). * **Old Age:** T1DM typically presents in childhood or adolescence (peak incidence at puberty) [3]. While "Latent Autoimmune Diabetes in Adults" (LADA) exists, old age is a primary risk factor for **Type 2 DM**, not Type 1. * **Gestational Diabetes:** This is a risk factor for the future development of **Type 2 DM** in the mother, not Type 1. **High-Yield Clinical Pearls for NEET-PG:** * **HLA Associations:** DR3 and DR4 (Increased risk); **HLA-DQB1*0602** (Protective against T1DM). * **Autoantibodies:** Anti-GAD65 (most persistent), IA-2, and Zinc Transporter 8 (ZnT8) antibodies. * **Concordance:** The monozygotic twin concordance rate for T1DM is ~30-50% (much lower than T2DM, which is >90%) [1], [3]. * **Associated Conditions:** Always screen for other autoimmune diseases like Celiac disease and Hashimoto’s thyroiditis (Polyglandular Autoimmune Syndromes) [1].

Q: Serum testosterone levels exceeding 200 ng/dL is suggestive of which condition?

Adrenal tumor. **Explanation:** In clinical practice, the degree of androgen elevation is a critical diagnostic marker for differentiating between functional and neoplastic causes of hyperandrogenism. **1. Why Adrenal Tumor is Correct:** Serum testosterone levels **exceeding 200 ng/dL** are highly suspicious for an **androgen-secreting tumor**, most commonly of ovarian or adrenal origin (e.g., Sertoli-Leydig cell tumor or Adrenal Cortical Carcinoma). While PCOS causes mild to moderate elevations, a rapid onset of virilization (clitoromegaly, deepening of voice) and testosterone levels >200 ng/dL necessitate imaging (CT/MRI or Ultrasound) to rule out a malignancy. **2. Why Other Options are Incorrect:** * **Polycystic Ovary Syndrome (PCOS):** This is the most common cause of hyperandrogenism, but testosterone levels are typically mildly elevated (usually ** 200 ng/dL are rare in PCOS. * **Metabolic Syndrome:** While often associated with PCOS and insulin resistance (which lowers SHBG and increases free testosterone), it does not independently cause extreme elevations of total testosterone. * **Ovarian Atresia:** This refers to the natural degeneration of follicles. It leads to a decrease in estrogen rather than a pathological increase in testosterone. **Clinical Pearls for NEET-PG:** * **Cut-off Values:** Testosterone **>200 ng/dL** suggests a tumor. DHEAS **>700 µg/dL** specifically suggests an **adrenal source/tumor**. * **Rapid Onset:** If symptoms of virilization appear rapidly (within 6 months), always suspect a tumor over PCOS. * **First-line Investigation:** For suspected androgen-secreting tumors, transvaginal ultrasound (TVS) is often the initial step to look for ovarian masses, followed by adrenal imaging.

Q: What is the pathognomic feature of hyperparathyroidism?

Subperiosteal resorption of phalanges. Primary Hyperparathyroidism (PHPT) is characterized by excessive secretion of Parathyroid Hormone (PTH), which stimulates osteoclast activity, leading to generalized bone resorption (Osteitis Fibrosa Cystica) [1]. **Why Subperiosteal Resorption is the Correct Answer:** Subperiosteal bone resorption is considered the **most specific and pathognomonic** radiographic sign of hyperparathyroidism. It occurs due to PTH-induced activation of osteoclasts in the subperiosteal region. It is most classically seen on the **radial aspect of the middle phalanges** of the 2nd and 3rd fingers. When seen on an X-ray, it is virtually diagnostic of hyperparathyroidism. **Analysis of Incorrect Options:** * **Loss of Lamina Dura (Option B):** This refers to the disappearance of the cortical bone lining the tooth socket. While it is a classic early sign of hyperparathyroidism, it is **not pathognomonic** because it can also be seen in other conditions like Paget’s disease, osteomalacia, and severe osteoporosis. * **Brown’s Tumor (Option C):** These are lytic bone lesions (osteoclastomas) filled with fibrous tissue and vascularized hemorrhage. While highly characteristic of advanced PHPT, they are a late manifestation and can mimic other giant cell tumors, making them less specific than subperiosteal resorption. * **Option A:** This is a repetition of the question stem and not a clinical feature. **NEET-PG High-Yield Pearls:** * **Salt and Pepper Skull:** A classic radiographic finding in PHPT due to multiple tiny lucencies in the calvarium. * **Rugger-Jersey Spine:** Characteristic of **Secondary Hyperparathyroidism** (seen in Chronic Kidney Disease) [2]. * **Most common cause of PHPT:** Solitary Parathyroid Adenoma (~85%) [3]. * **Biochemical Triad:** Hypercalcemia, Hypophosphatemia, and elevated PTH [2].

Q: A 35-year-old male, a known case of MEN 1, presents to the OPD with urinary stones and increased serum calcium. What is the next investigation to be done?

Secretin study. **Explanation:** The patient is a known case of **MEN 1 (Wermer Syndrome)**, which is characterized by the "3 Ps": **P**arathyroid (95% frequency), **P**ancreatic islet cell tumors, and **P**ituitary tumors. The presentation of urinary stones and hypercalcemia confirms **Primary Hyperparathyroidism** [1], the most common initial manifestation of MEN 1. Once a component of MEN 1 is identified, the clinician must screen for the other components. Among pancreatic neuroendocrine tumors (NETs) in MEN 1, **Gastrinoma (Zollinger-Ellison Syndrome)** is the most common symptomatic tumor. The **Secretin Stimulation Test** is the most sensitive and specific provocative test for diagnosing Gastrinoma. A positive result is a rise in serum gastrin >200 pg/mL above baseline. **Analysis of Incorrect Options:** * **A. Urinary metanephrine:** This is the screening test for Pheochromocytoma, which is a component of **MEN 2A and 2B**, not MEN 1. * **C. Serum calcitonin:** This is a marker for Medullary Thyroid Carcinoma (MTC), which is the hallmark of **MEN 2A and 2B**. * **D. 72-hour prolonged fasting:** This is the gold standard for diagnosing **Insulinoma**. While insulinomas occur in MEN 1, Gastrinomas are more frequent, and the Secretin study is the prioritized investigation for the most common MEN 1-associated pancreatic NET. **Clinical Pearls for NEET-PG:** * **MEN 1 Gene:** Mutation on Chromosome 11q13 (Menin protein). * **Order of appearance:** Hyperparathyroidism is usually the first clinical sign [1]. * **Gastrinoma Location:** In MEN 1, gastrinomas are often multiple and frequently located in the duodenum (Gastrinoma triangle) rather than the pancreas. * **MEN 2A:** Medullary Thyroid CA + Pheochromocytoma + Hyperparathyroidism. * **MEN 2B:** Medullary Thyroid CA + Pheochromocytoma + Mucosal Neuromas/Marfanoid habitus.

Q: Which of the following is NOT associated with hypothyroidism?

Low cholesterol. In hypothyroidism, the metabolic rate slows down, leading to characteristic biochemical changes. [1] **Explanation of the Correct Answer:** **D. Low cholesterol** is the correct answer because hypothyroidism is actually associated with **Hypercholesterolemia** (High cholesterol). Thyroid hormones normally upregulate the expression of LDL receptors on hepatocytes. [1] In a hypothyroid state, there is a decrease in the number and activity of these receptors, leading to reduced clearance of LDL from the plasma. Consequently, total cholesterol and LDL levels rise, making hypothyroidism a secondary cause of dyslipidemia. [1] **Explanation of Incorrect Options:** * **A. Low T3:** In overt hypothyroidism, both T4 and T3 levels are typically low as the thyroid gland fails to produce sufficient hormones. (Note: T4 is the more reliable diagnostic marker as T3 may remain normal in early stages). [2] * **B. High TSH:** This is the most sensitive screening test for primary hypothyroidism. Due to the lack of negative feedback from low T4/T3, the anterior pituitary increases TSH production. [2] * **C. High Triglycerides:** Hypothyroidism leads to decreased activity of **Lipoprotein Lipase (LPL)**, the enzyme responsible for clearing triglyceride-rich lipoproteins (VLDL and chylomicrons), resulting in hypertriglyceridemia. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Hashimoto’s Thyroiditis (look for anti-TPO antibodies). * **Lipid Profile:** Expect High LDL, High Total Cholesterol, and High Triglycerides. * **Hyponatremia:** Hypothyroidism can cause dilutional hyponatremia due to impaired free water excretion (increased ADH). * **Creatine Kinase (CK):** Often elevated in hypothyroidism due to increased muscle membrane permeability (hypothyroid myopathy). * **Anemia:** Most commonly Normocytic Normochromic, but can be Macrocytic (associated Pernicious Anemia).

Q: Which of the following conditions does NOT cause granulomatous hypercalcemia?

Systemic lupus erythematosus. The underlying mechanism of **granulomatous hypercalcemia** is the autonomous, extra-renal production of **1,25-dihydroxyvitamin D (Calcitriol)**. In granulomatous diseases, activated macrophages within the granuloma express the enzyme **1-alpha-hydroxylase**. Unlike the renal enzyme, this macrophage-derived enzyme is not inhibited by high levels of calcitriol or low PTH, leading to unregulated intestinal calcium absorption and hypercalcemia. * **Systemic Lupus Erythematosus (SLE) (Correct Answer):** SLE is a systemic autoimmune connective tissue disorder characterized by immune complex deposition and autoantibody production [2]. It is **not** a granulomatous disease. While SLE can rarely be associated with hypercalcemia (usually due to co-existing hyperparathyroidism or malignancy), it does not cause hypercalcemia via the 1-alpha-hydroxylase mechanism [2], [3]. * **Sarcoidosis:** The classic prototype of granulomatous hypercalcemia. Up to 10% of patients develop hypercalcemia due to high calcitriol levels produced by sarcoid granulomas [1]. * **Tuberculosis:** A common infectious cause of granulomatous hypercalcemia. Chronic inflammation and macrophage activation in TB lead to increased 1-alpha-hydroxylase activity. * **Berylliosis:** A chronic occupational lung disease caused by beryllium exposure, which histologically presents with non-caseating granulomas identical to sarcoidosis, leading to similar vitamin D-mediated hypercalcemia. **High-Yield Clinical Pearls for NEET-PG:** * **PTH Levels:** In granulomatous hypercalcemia, PTH is typically **suppressed** (low), while 1,25(OH)₂D is **elevated**. * **Treatment:** Glucocorticoids are the first-line treatment as they inhibit the 1-alpha-hydroxylase enzyme in macrophages. * **Other Causes:** Other granulomatous causes include Leprosy, Histoplasmosis, Coccidioidomycosis, and Cat-scratch disease. Certain lymphomas (Hodgkin’s) can also utilize this mechanism.

Question 1

Which of the following is associated with secondary hyperparathyroidism?

Accepted Answer

Chronic renal failure

Answer

Parathyroid adenoma

Answer

Marked hypercalcemia

Answer

Parathyroidectomy relieves the symptoms

Question 2

Which of the following is a risk factor for developing Type 1 Diabetes mellitus?

Accepted Answer

HLA DR3

Answer

Male Gender

Answer

Old age

Answer

Gestational diabetes

Question 3

Serum testosterone levels exceeding 200 ng/dL is suggestive of which condition?

Accepted Answer

Adrenal tumor

Answer

Polycystic Ovary Syndrome (PCOS)

Answer

Metabolic syndrome

Answer

Ovarian atresia

Question 4

What is the pathognomic feature of hyperparathyroidism?

Accepted Answer

Subperiosteal resorption of phalanges

Answer

Pathognomic feature of hyperparathyroidism

Answer

Loss of lamina dura

Answer

Brown's tumor

Question 5

A 35-year-old male, a known case of MEN 1, presents to the OPD with urinary stones and increased serum calcium. What is the next investigation to be done?

Accepted Answer

Secretin study

Answer

Urinary metanephrine

Answer

Serum calcitonin levels

Answer

72-hour prolonged fasting

Question 6

Which of the following is NOT associated with hypothyroidism?

Accepted Answer

Low cholesterol

Answer

Low T3

Answer

High TSH

Answer

High Triglycerides

Question 7

A 42-year-old woman presents with complaints of dry skin, fatigue, and weight gain over the past 3 months. She has no significant past medical history and is not on any medications. Physical examination reveals a blood pressure of 110/70 mm Hg, pulse of 52/min, and normal heart and lung sounds. Her skin feels rough and dry. Her biochemistry is normal, but the thyroid-stimulating hormone (TSH) level is 39 mU/L (normal range: 0.5-5 mU/L). What is the most likely cause for her elevated TSH?

Accepted Answer

Autoimmune hypothyroidism

Answer

Trauma

Answer

Radioactive iodine ingestion

Answer

Parathyroid surgery

Question 8

Which of the following conditions does NOT cause granulomatous hypercalcemia?

Accepted Answer

Systemic lupus erythematosus

Answer

Tuberculosis

Answer

Sarcoidosis

Answer

Berylliosis

Question 9

A patient presents with amenorrhea and galactorrhea, and has elevated prolactin levels. She is not pregnant. In addition to evaluating for a prolactinoma, what other investigations can assess the cause of hyperprolactinemia?

Accepted Answer

Thyrotropin-releasing hormone (TRH) stimulation test

Answer

Corticotropin-releasing hormone (CRH) stimulation test

Answer

Dopamine challenge test

Answer

Histamine type II receptor antagonist challenge

Question 10

Following hypophysectomy, why is vasopressin administered intramuscularly?

Accepted Answer

To replace antidiuretic hormone (ADH) that is normally secreted by the pituitary

Answer

To manage growth failure

Answer

To prevent syndrome of inappropriate antidiuretic hormone (SIADH)

Answer

To decrease cerebral edema and lower intracranial pressure

Endocrinology — MCQs

Endocrinology — MCQs

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