Endocrinology Practice Questions

Q: Zinc transporter 8 (ZnT8) antibody is seen in which of the following conditions?

Type 1 diabetes mellitus. **Explanation:** **Type 1 Diabetes Mellitus (T1DM)** is an autoimmune condition characterized by the destruction of pancreatic beta cells. **Zinc transporter 8 (ZnT8)** is a protein localized in the membrane of insulin secretory granules within these beta cells. It plays a critical role in transporting zinc into the granules, which is essential for the structural stabilization and crystallization of insulin hexamers. Antibodies against ZnT8 (ZnT8Ab) are one of the major autoantibodies used in the diagnosis of T1DM, alongside Glutamic Acid Decarboxylase (GAD65), Insulinoma-Associated Protein 2 (IA-2), and Insulin Autoantibodies (IAA). ZnT8Ab is particularly high-yield because it can be present even when other markers are negative, increasing the diagnostic sensitivity for T1DM. **Analysis of Incorrect Options:** * **Hashimoto's thyroiditis:** Associated with antibodies against thyroid peroxidase (anti-TPO) and thyroglobulin (anti-Tg). * **Hypoparathyroidism:** Often associated with antibodies against the calcium-sensing receptor (CaSR) in autoimmune cases (APS Type 1). * **Type A insulin resistance:** This is a genetic defect in the insulin receptor signaling pathway (e.g., INSR gene mutations), not an autoimmune process involving ZnT8. **High-Yield Clinical Pearls for NEET-PG:** * **ZnT8 (SLC30A8 gene):** Polymorphisms in this gene are also linked to an increased risk of Type 2 Diabetes. * **Diagnostic Utility:** ZnT8Ab is often the last antibody to appear before clinical onset and is a strong predictor of rapid progression to insulin dependence. * **LADA:** ZnT8 antibodies can also be found in patients with Latent Autoimmune Diabetes in Adults.

Q: Goitrous hypothyroidism commonly occurs in all of the following conditions except?

Thyroprivic hypothyroidism. The core concept behind **Goitrous Hypothyroidism** is the compensatory hypertrophy of the thyroid gland. When thyroid hormone levels (T3/T4) fall, the pituitary gland increases the secretion of **TSH** [2]. If the thyroid tissue is present and capable of responding, TSH stimulates glandular growth, leading to a goiter. **Why Thyroprivic Hypothyroidism is the correct answer:** "Thyroprivic" refers to the **loss or absence of thyroid tissue**. This occurs in conditions like thyroid agenesis (congenital), surgical removal (thyroidectomy), or total destruction via radioactive iodine therapy [1]. Since there is little to no thyroid tissue left to respond to TSH stimulation, a goiter cannot form. This is a "non-goitrous" form of hypothyroidism. **Analysis of Incorrect Options:** * **Hashimoto’s Thyroiditis:** This is the most common cause of goitrous hypothyroidism in iodine-sufficient areas. Lymphocytic infiltration and TSH stimulation lead to a firm, rubbery goiter. * **Dyshormonogenesis:** These are genetic defects in the enzymatic pathways of thyroid hormone synthesis (e.g., Pendred syndrome) [1]. The biosynthetic block leads to low T4, high TSH, and subsequent thyroid enlargement. * **Iodine Deficiency:** The most common cause of goitrous hypothyroidism worldwide (Endemic Goiter). Lack of iodine prevents hormone synthesis, triggering a massive TSH response and glandular hypertrophy. **High-Yield Clinical Pearls for NEET-PG:** * **Wolff-Chaikoff Effect:** Goitrous hypothyroidism induced by excessive iodine intake (e.g., Amiodarone). * **Pendred Syndrome:** Characterized by dyshormonogenetic goiter and sensorineural deafness. * **Most common cause of Goiter:** Iodine deficiency (Worldwide); Hashimoto’s (Developed nations). * **Thyroprivic vs. Trophoprivic:** Thyroprivic is a primary thyroid tissue loss; Trophoprivic refers to secondary hypothyroidism due to loss of TSH (pituitary failure).

Q: Which of the following is the most common cause of hypergonadotropic hypogonadism in males?

Klinefelter's syndrome. **Explanation:** **Hypergonadotropic hypogonadism** (Primary Hypogonadism) is characterized by testicular failure leading to low testosterone levels, which results in a compensatory rise in gonadotropins (FSH and LH) due to the loss of negative feedback on the pituitary gland [1]. **Why Klinefelter’s Syndrome is correct:** Klinefelter’s syndrome (47, XXY) is the **most common congenital cause** and the most common cause overall of primary testicular failure [1]. The extra X chromosome leads to progressive hyalinization and fibrosis of the seminiferous tubules and dysfunction of Leydig cells [1]. This results in azoospermia, low testosterone, and characteristically elevated FSH and LH levels [1]. **Analysis of Incorrect Options:** * **Viral Orchitis (e.g., Mumps):** While it is a common *acquired* cause of testicular atrophy, it is less frequent than Klinefelter’s syndrome in the general population presenting with hypogonadism [1]. * **Kallmann’s Syndrome:** This is a form of **hypogonadotropic hypogonadism** (Secondary Hypogonadism). It is caused by a failure of GnRH-secreting neurons to migrate, leading to low FSH/LH and low testosterone, often associated with anosmia. * **Noonan Syndrome:** Often called the "Male Turner Syndrome," it can cause cryptorchidism and primary hypogonadism, but it is significantly rarer than Klinefelter’s syndrome [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Karyotype:** 47, XXY is the most common; Barr bodies are present on buccal smear. * **Clinical Features:** Tall stature, eunuchoid body proportions, gynecomastia, small firm testes (<2 cm), and female-pattern hair distribution [1]. * **Biochemical Profile:** ↓ Testosterone, ↑ FSH, ↑ LH, and ↑ Estradiol [1]. * **Risk:** Increased risk of breast cancer (20x) and extragonadal germ cell tumors (mediastinal) [1].

Q: Recurrent balanoposthitis is commonly seen in which of the following conditions?

Diabetes Mellitus. **Explanation:** **Recurrent balanoposthitis** (inflammation of the glans penis and prepuce) is a classic clinical marker for **Diabetes Mellitus (DM)**. In many cases, it is the initial presenting symptom that leads to a new diagnosis of Type 2 DM. **1. Why Diabetes Mellitus is the Correct Answer:** The underlying mechanism is primarily due to **hyperglycosuria** (glucose in the urine). The presence of sugar on the skin of the genital area provides an ideal culture medium for fungi, specifically *Candida albicans*. Furthermore, hyperglycemia impairs neutrophil function and cell-mediated immunity, making diabetic patients more susceptible to persistent and recurrent fungal infections. Chronic inflammation can eventually lead to acquired phimosis. **2. Analysis of Incorrect Options:** * **Herpes Simplex (HSV):** While HSV causes genital ulcers (vesicles on an erythematous base), it typically presents as episodic painful sores rather than generalized inflammation of the glans (balanitis). It is not the "most common" cause of generalized recurrent balanoposthitis in clinical practice compared to DM. * **Smoking & Alcohol consumption:** These are general risk factors for various systemic diseases but have no direct causal or strong statistical link to the development of balanoposthitis. **Clinical Pearls for NEET-PG:** * **High-Yield Association:** In any uncircumcised male presenting with recurrent balanoposthitis or fungal infections, the first investigation to perform is a **Fast Blood Sugar (FBS) or HbA1c**. * **SGLT-2 Inhibitors:** Modern diabetes medications like Dapagliflozin increase urinary glucose excretion and are notorious for causing an increased risk of genital mycotic infections (balanoposthitis in men, vulvovaginitis in women). * **Pathogen:** *Candida albicans* is the most common organism isolated in diabetic balanoposthitis.

Q: Which joint is commonly involved in diabetic arthropathy?

Foot. **Explanation:** The correct answer is **Foot**. Diabetic arthropathy primarily manifests as **Charcot Neuroarthropathy (Charcot Joint)**, which most frequently involves the small joints of the foot and the ankle complex [1]. **Why the Foot is the Correct Answer:** The underlying pathophysiology involves a combination of **peripheral neuropathy** (loss of pain and proprioception) and **autonomic neuropathy** (increased blood flow leading to bone resorption). Repetitive microtrauma to a desensitized foot leads to progressive joint destruction, subluxation, and characteristic deformities like the "rocker-bottom foot." The **tarsometatarsal (Lisfranc) and metatarsophalangeal joints** are the most common sites of involvement [1]. **Analysis of Incorrect Options:** * **Ankle:** While the ankle can be involved in Charcot joint, it is statistically less common than the midfoot and forefoot joints [1]. * **Knee:** Charcot joint of the knee is more classically associated with **Tabes Dorsalis (Syphilis)** rather than Diabetes Mellitus. * **Shoulder:** Shoulder involvement in diabetes is typically associated with **Adhesive Capsulitis (Frozen Shoulder)** or calcific tendonitis, which are soft tissue disorders rather than the destructive arthropathy (Charcot) implied by the term "diabetic arthropathy." **High-Yield Clinical Pearls for NEET-PG:** * **Rocker-bottom foot:** A classic deformity caused by the collapse of the midfoot arch in Charcot joint [1]. * **Differential Diagnosis:** An acute Charcot foot often presents as red, hot, and swollen, frequently misdiagnosed as **cellulitis or osteomyelitis**. * **Key Distinguishing Factor:** In Charcot, the redness usually subsides when the foot is elevated for 5–10 minutes (unlike cellulitis). * **Treatment:** The gold standard for acute Charcot neuroarthropathy is **Total Contact Casting (TCC)** to offload the joint.

Q: A 53-year-old man presents for a physical. His father had diabetes and died of congestive heart failure, reportedly due to "bronze diabetes." The patient complains of vague fatigue and arthralgias. Which test would you order to confirm the suspicion of hereditary hemochromatosis?

Transferrin saturation. **Explanation:** The clinical presentation of fatigue, arthralgias, and a family history of "bronze diabetes" (the triad of cirrhosis, hyperpigmentation, and diabetes) strongly suggests **Hereditary Hemochromatosis (HH)** [2]. This is an autosomal recessive disorder, most commonly due to a mutation in the **HFE gene**, leading to excessive intestinal iron absorption and organ deposition [1]. **Why Transferrin Saturation is Correct:** The initial screening test of choice for HH is **Transferrin Saturation (TSAT)**. A value **>45%** is highly sensitive and indicates iron overload. If TSAT is elevated, serum ferritin is measured [1]. Confirmation is typically achieved through **HFE gene mutation analysis** (C282Y/H63D) [1], [2]. While liver biopsy was previously the gold standard, it is now reserved for assessing fibrosis or when genetic testing is inconclusive [1]. **Why Incorrect Options are Wrong:** * **Antimitochondrial antibodies (AMA):** The hallmark of Primary Biliary Cholangitis (PBC), which presents with pruritus and jaundice, not iron overload. * **Ceruloplasmin:** Low levels are seen in Wilson’s Disease (copper overload), which typically presents in younger patients with neurological symptoms and Kayser-Fleischer rings. * **Heterophil antibodies:** Used for the Monospot test to diagnose Infectious Mononucleosis (EBV). **NEET-PG High-Yield Pearls:** * **Most common mutation:** C282Y (substitution of tyrosine for cysteine) [1], [2]. * **Classic Triad:** Cirrhosis, Diabetes ("Bronze Diabetes"), and Skin Hyperpigmentation [2]. * **Arthropathy:** Characterized by "hook-like" osteophytes on X-ray, commonly involving the 2nd and 3rd MCP joints. * **Cardiac involvement:** Most commonly presents as Restrictive Cardiomyopathy (early) or Dilated Cardiomyopathy (late). * **Treatment:** Therapeutic phlebotomy is the mainstay of management [1].

Question 1

Zinc transporter 8 (ZnT8) antibody is seen in which of the following conditions?

Accepted Answer

Type 1 diabetes mellitus

Answer

Hashimoto's thyroiditis

Answer

Hypoparathyroidism

Answer

Type A insulin resistance

Question 2

Goitrous hypothyroidism commonly occurs in all of the following conditions except?

Accepted Answer

Thyroprivic hypothyroidism

Answer

Hashimoto's thyroiditis

Answer

Dyshoromonogenesis

Answer

Iodine deficiency

Question 3

Which of the following is the most common cause of hypergonadotropic hypogonadism in males?

Accepted Answer

Klinefelter's syndrome

Answer

Viral orchitis

Answer

Kallman's syndrome

Answer

Noonan syndrome

Question 4

Which of the following is NOT a common clinical manifestation of thyrotoxicosis?

Accepted Answer

Weight gain

Answer

Gynaecomastia

Answer

Loss of libido

Answer

Goiter

Question 5

Recurrent balanoposthitis is commonly seen in which of the following conditions?

Accepted Answer

Diabetes Mellitus

Answer

Herpes simplex

Answer

Smoking

Answer

Alcohol consumption

Question 6

A 25-year-old male presents with occasional severe headaches, nausea, and vomiting. Blood pressure while sitting is 230/130 mmHg with a heart rate of 90 beats/min. Upon standing, the blood pressure drops to 200/100 mmHg and the heart rate increases to 140 beats/min. Cardiovascular examination reveals tachycardia with normal S1 and S2 sounds. The patient's lungs are clear. Optic discs are blurred, but there are no exudates or hemorrhages. Select the appropriate treatment for this condition.

Accepted Answer

Phentolamine

Answer

Labetalol

Answer

Nitroprusside

Answer

Hydralazine

Question 7

A 52-year-old woman presents with complaints of fatigue, flank pain, headache, hematuria, and abdominal pain. A sestamibi scan demonstrates persistent uptake in the right superior parathyroid gland at 2 hours. Which of the following laboratory values is most suggestive of her diagnosis?

Accepted Answer

Serum calcium above 11 mg/dL

Answer

Serum acid phosphatase above 120 IU/L

Answer

Serum alkaline phosphatase above 120 IU/L

Answer

Urinary calcium below 100 mg/day

Question 8

Which joint is commonly involved in diabetic arthropathy?

Accepted Answer

Foot

Answer

Ankle

Answer

Knee

Answer

Shoulder

Question 9

A 53-year-old man presents for a physical. His father had diabetes and died of congestive heart failure, reportedly due to "bronze diabetes." The patient complains of vague fatigue and arthralgias. Which test would you order to confirm the suspicion of hereditary hemochromatosis?

Accepted Answer

Transferrin saturation

Answer

Antimitochondrial antibodies

Answer

Ceruloplasmin

Answer

Heterophil antibodies

Question 10

Hyperpigmentation is seen in all except?

Accepted Answer

Cushing's syndrome

Answer

Peutz-Jeghers syndrome

Answer

Addison's disease

Answer

Albright syndrome

Endocrinology — MCQs

Endocrinology — MCQs

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