Endocrinology Practice Questions

Q: Cutting of the pituitary stalk decreases all of the following hormones except?

Prolactin. The secretion of anterior pituitary hormones is primarily regulated by the hypothalamus via the **hypothalamic-hypophyseal portal system**. Most anterior pituitary hormones (ACTH, TSH, growth hormone, FSH, LH) are under **stimulatory** control by hypothalamic releasing factors [1]. However, **Prolactin** is the unique exception; it is under tonic **inhibitory** control by **Dopamine** [3]. When the pituitary stalk is severed (Pituitary Stalk Interruption), the connection between the hypothalamus and the pituitary is lost. This results in: 1. **Decreased levels** of hormones that require hypothalamic stimulation (ACTH, GH, FSH, LH, and TSH). 2. **Increased levels** of Prolactin, because the inhibitory influence of Dopamine is removed [3]. This phenomenon is often referred to as "Stalk Effect" hyperprolactinemia. **Analysis of Options:** * **A, B, and D (ACTH, GH, FSH):** These are incorrect because their secretion depends on CRH, GHRH, and GnRH, respectively. Cutting the stalk prevents these releasing hormones from reaching the anterior pituitary, leading to a deficiency [4]. * **C (Prolactin):** This is the correct answer because its levels **increase** rather than decrease when the inhibitory dopaminergic pathway is disrupted. **High-Yield Clinical Pearls for NEET-PG:** * **Dopamine = Prolactin Inhibiting Factor:** Any drug that blocks dopamine (e.g., antipsychotics like Haloperidol or prokinetics like Metoclopramide) will cause hyperprolactinemia. * **Stalk Effect vs. Prolactinoma:** In stalk compression (e.g., by a Craniopharyngioma), prolactin levels are usually 200 ng/mL strongly suggest a Prolactinoma. * **Posterior Pituitary:** Stalk transection also leads to **Diabetes Insipidus** because ADH (Vasopressin) and Oxytocin, synthesized in the hypothalamus, can no longer be transported to the posterior pituitary for release [2].

Q: What is the imaging modality of choice for parathyroid pathology?

Tc 99 scan. **Explanation:** The imaging modality of choice for localizing parathyroid adenomas or hyperplasia is the **Technetium-99m (Tc-99m) Sestamibi scan**. This is a nuclear medicine study based on the principle that Sestamibi (a lipophilic cation) is taken up by mitochondria-rich cells. Parathyroid adenomas contain high concentrations of oxyphil cells with abundant mitochondria, which retain the tracer longer than the surrounding thyroid tissue. This "differential washout" allows for the identification of ectopic or enlarged parathyroid glands. **Analysis of Options:** * **A. CT scan:** While 4D-CT is increasingly used for surgical planning in re-operative cases, it is not the initial imaging of choice due to high radiation exposure and lower sensitivity compared to Sestamibi in primary cases. * **B. Gallium scan:** This is primarily used for detecting inflammation, infections, or certain lymphomas; it has no role in parathyroid imaging. * **C. Thallium scan:** Historically used in combination with Technetium (subtraction scanning), it has been largely replaced by Sestamibi due to the latter's superior image quality and sensitivity. * **D. Tc 99 scan (Correct):** Specifically, the **Tc-99m Sestamibi scan** (often combined with SPECT) is the gold standard for preoperative localization. **Clinical Pearls for NEET-PG:** * **First-line investigation:** Neck Ultrasound (USG) is often the initial step due to cost and availability, but **Sestamibi** is the most definitive for localization. * **Ectopic Parathyroid:** Sestamibi is particularly superior for identifying ectopic glands (e.g., in the mediastinum). * **Hungry Bone Syndrome:** A common post-operative complication of parathyroidectomy characterized by profound hypocalcemia and hypophosphatemia. * **Definitive Treatment:** Surgical excision (Parathyroidectomy) remains the only curative treatment for primary hyperparathyroidism.

Q: All of the following are associated with insulin resistance except?

Calcific aortic valve disease. **Explanation:** Insulin resistance (IR) is a systemic metabolic state characterized by a decreased tissue response to insulin, leading to compensatory hyperinsulinemia. This condition is the hallmark of Metabolic Syndrome and is associated with specific cutaneous, metabolic, and cardiovascular manifestations. **Why Calcific Aortic Valve Disease (CAVD) is the correct answer:** While insulin resistance is a major risk factor for **atherosclerotic cardiovascular disease** (CAD), it is not a direct causative factor for **Calcific Aortic Valve Disease**. CAVD is primarily a degenerative process involving chronic inflammation, lipid accumulation, and osteoblast-like phenotypic changes in valve leaflets. While it shares risk factors with IR (like age and hypertension), it is not considered a classic clinical manifestation of the insulin resistance syndrome. **Analysis of other options:** * **Acanthosis Nigricans:** High insulin levels cross-react with **IGF-1 receptors** on keratinocytes and fibroblasts, leading to epidermal hyperplasia and the characteristic velvety, hyperpigmented plaques [1]. * **Lipodystrophy:** Both congenital and acquired lipodystrophies are strongly associated with severe insulin resistance due to the inability of adipose tissue to store triglycerides, leading to ectopic fat deposition in the liver and muscle [1]. * **Gout:** Hyperinsulinemia decreases the renal excretion of uric acid by upregulating the **URAT1 transporter** in the proximal tubule, leading to hyperuricemia and gout. **Clinical Pearls for NEET-PG:** * **PCOS** and **Nonalcoholic Fatty Liver Disease (NAFLD)** are also major clinical markers of insulin resistance. * **HAIR-AN Syndrome:** A high-yield triad consisting of **H**yper**a**ndrogenism, **I**nsulin **R**esistance, and **A**canthosis **N**igricans. * The most sensitive gold-standard test for measuring insulin resistance is the **Hyperinsulinemic Euglycemic Clamp study.**

Q: A 48-year-old Caucasian man, diagnosed with diabetes 5 years ago, presents with palpitations. Physical examination reveals diffuse skin darkening and testicular atrophy. Laboratory studies show elevated liver function and elevated blood sugars. A liver biopsy shows significantly elevated iron levels, leading to a diagnosis of hereditary hemochromatosis. Which one of the following laboratory findings is seen in hereditary hemochromatosis?

Decreased total iron-binding capacity. The clinical presentation of "Bronze Diabetes" (skin darkening and diabetes), testicular atrophy, and hepatomegaly in a middle-aged male is classic for **Hereditary Hemochromatosis (HH)** [2]. This is an autosomal recessive disorder (most commonly the HFE gene mutation) characterized by excessive intestinal iron absorption leading to systemic iron overload [1], [2]. **Why Option D is Correct:** In HH, the body is saturated with iron. **Total Iron-Binding Capacity (TIBC)** is an indirect measure of transferrin levels [4]. When iron stores are excessively high, the liver decreases the production of transferrin to prevent further transport of iron. Furthermore, since the existing transferrin molecules are highly saturated with iron (Transferrin Saturation >45-50%), the "capacity" to bind more iron is significantly **decreased**. **Why the Other Options are Incorrect:** * **Option A:** Decreased serum ceruloplasmin is the screening hallmark for **Wilson’s Disease** (copper overload), not hemochromatosis [3]. * **Option B:** Serum ferritin is an acute-phase reactant and a marker of total body iron stores. In HH, serum ferritin is **significantly elevated** (often >200-300 ng/mL) [1]. * **Option C:** Serum iron is **elevated** in HH due to increased absorption and release from damaged hepatocytes. **NEET-PG High-Yield Pearls:** * **Screening Test of Choice:** Transferrin Saturation (most sensitive early marker). * **Confirmatory Test:** Genetic testing for HFE mutation (C282Y) [1]. * **Gold Standard for Iron Quantification:** MRI (T2*) or Liver Biopsy (Perls' Prussian Blue stain) [1]. * **Classic Triad:** Cirrhosis, Diabetes Mellitus, and Skin Pigmentation [2]. * **Treatment:** Therapeutic phlebotomy is the mainstay; Deferoxamine is used if phlebotomy is contraindicated [1].

Q: In patients with significant atherosclerosis, which of the following conditions is increased approximately 100-fold in those with comorbid diabetes compared to non-diabetic patients?

Lower limb ischemia. The correct answer is **Lower limb ischemia (Peripheral Arterial Disease)**. While diabetes mellitus (DM) is a major risk factor for all forms of macrovascular disease, the relative risk increase is most dramatic for lower extremity involvement [1]. In patients with atherosclerosis, the presence of diabetes increases the risk of gangrene and non-traumatic lower limb amputation by approximately **100-fold** compared to non-diabetics. This is due to a combination of accelerated atherosclerosis in the infra-popliteal (distal) vessels, peripheral neuropathy (leading to unnoticed trauma), and impaired wound healing. **Analysis of Incorrect Options:** * **A & B (Myocardial Infarction and Ischemic Stroke):** Diabetes is indeed a "coronary artery disease equivalent," increasing the risk of MI and stroke by 2 to 4 times. However, this increase is significantly lower than the 100-fold risk associated with limb-threatening ischemia. * **D (Vertebrobasilar insufficiency):** While DM contributes to cerebrovascular disease, it does not show the specific, massive statistical predilection for the vertebrobasilar system that it does for the distal lower limb arteries. **High-Yield Clinical Pearls for NEET-PG:** * **Pattern of Involvement:** Atherosclerosis in diabetics tends to be more **distal** (below the knee, involving tibial and peroneal arteries) and **multisegmental** compared to non-diabetics [1]. * **The "Rule of 100":** Remember that DM increases the risk of lower limb gangrene by ~100x. * **Monckeberg Medial Sclerosis:** Diabetics often have calcification of the arterial media, which can lead to falsely elevated Ankle-Brachial Index (ABI) readings. * **Leading Cause:** Diabetes is the leading cause of non-traumatic lower extremity amputations worldwide.

Q: Which test can confirm autoimmune thyroiditis in a patient?

Thyroid peroxidase antibody (TPO). **Hashimoto’s thyroiditis (Chronic Autoimmune Thyroiditis)** is the most common cause of hypothyroidism in iodine-sufficient regions. The diagnosis is primarily clinical and biochemical, supported by the presence of specific autoantibodies. 1. **Why Option A is correct:** **Thyroid Peroxidase (TPO) antibodies** are the hallmark of autoimmune thyroiditis. They are present in more than **90-95%** of patients with Hashimoto’s. TPO is the enzyme responsible for iodine oxidation and organification; antibodies against it lead to thyroid follicle destruction [1]. While **Antithyroglobulin (anti-Tg)** antibodies can also be present, TPO antibodies are more sensitive and have a stronger correlation with the progression to overt hypothyroidism [1]. 2. **Why other options are incorrect:** * **B. Antinuclear antibody (ANA):** This is a screening test for systemic autoimmune diseases like SLE. While patients with Hashimoto’s may have co-existing autoimmune conditions, ANA is not specific to the thyroid. * **C. Thyroid uptake resin:** This (T3 resin uptake) is an older test used to estimate Thyroid Binding Globulin (TBG) levels. It does not identify the underlying autoimmune etiology. * **D. Thyroid aspiration (FNAC):** While FNAC can show characteristic Hurthle cells and lymphocytic infiltration, it is **not** the first-line confirmatory test. It is reserved for cases where a dominant nodule is present to rule out malignancy (e.g., Lymphoma or Papillary Carcinoma). **NEET-PG High-Yield Pearls:** * **Most sensitive marker:** Anti-TPO antibodies. * **Histology:** Lymphocytic infiltration with germinal centers and **Hurthle cells** (Askanazy cells/oxyphilic cells). * **Risk:** Increased risk of **B-cell Thyroid Lymphoma**. * **USG Finding:** Diffuse heterogenous echogenicity (often described as a "pseudonodular" appearance).

Q: A female patient has elevated TSH and subnormal free T4. What is the likely diagnosis?

Primary hypothyroidism. ### Explanation **1. Why Option A is Correct:** The diagnosis of **Primary Hypothyroidism** is based on the failure of the thyroid gland itself. When the thyroid gland cannot produce sufficient hormones (Low Free T4), the negative feedback mechanism to the pituitary is lost [1]. This results in the anterior pituitary secreting compensatory high levels of **Thyroid Stimulating Hormone (TSH)** to "force" the gland to work. Therefore, the classic biochemical profile is **↑ TSH and ↓ Free T4** [1]. **2. Why Other Options are Incorrect:** * **Secondary Hypothyroidism:** This occurs due to pituitary or hypothalamic failure. Since the "stimulator" is broken, the TSH will be **low or inappropriately normal** in the presence of a low Free T4. * **Hyperthyroidism:** This is characterized by an overactive gland. The biochemical profile shows **↓ TSH and ↑ Free T4/T3** [1]. * **Subclinical Hypothyroidism:** This is an early stage of thyroid failure where the TSH is **elevated**, but the thyroid gland is still able to maintain **normal Free T4** levels. **3. NEET-PG High-Yield Pearls:** * **Most Common Cause:** Worldwide, iodine deficiency is the most common cause; however, in iodine-sufficient areas (and the most common autoimmune cause), it is **Hashimoto’s Thyroiditis**. * **Screening Gold Standard:** Serum **TSH** is the most sensitive initial screening test for thyroid dysfunction [1]. * **Wolff-Chaikoff Effect:** Transient hypothyroidism caused by the ingestion of a large amount of iodine (e.g., amiodarone or contrast) [2]. * **Treatment Goal:** The target in primary hypothyroidism is to normalize TSH using Levothyroxine (T4), usually taken on an empty stomach [3].

Q: Testicular descent is controlled by which factor?

Insulin-like factor 3 (INSL3). Testicular descent is a complex, two-stage process. The correct answer is **Insulin-like factor 3 (INSL3)** because it is the primary hormone responsible for the first phase of descent. ### **Mechanism of Testicular Descent** 1. **Transabdominal Phase (Weeks 8–15):** This stage is controlled by **INSL3**, a peptide hormone secreted by the fetal Leydig cells. INSL3 acts on its receptor (RXFP2) to cause the thickening and contraction of the **gubernaculum**, which anchors the testes near the internal inguinal ring. 2. **Inguinoscrotal Phase (Weeks 25–35):** This stage is primarily **androgen-dependent** (Testosterone/DHT). Androgens cause the regression of the cranial suspensory ligament and guide the testes through the inguinal canal into the scrotum. ### **Analysis of Incorrect Options** * **RANKL (B):** This is a cytokine involved in bone metabolism (osteoclast activation). It has no role in gonadal development or descent. * **FSH (C):** Follicle-Stimulating Hormone is essential for spermatogenesis and Sertoli cell function but does not trigger the mechanical descent of the testes. * **LH (D):** While LH stimulates Leydig cells to produce testosterone (important for the second phase), **INSL3** is the specific factor required for the initial gubernacular development. ### **High-Yield Clinical Pearls for NEET-PG** * **Cryptorchidism:** Failure of descent is most commonly seen in preterm infants. The most common site of an undescended testis is the **inguinal canal**. * **Malignancy Risk:** Cryptorchidism increases the risk of testicular germ cell tumors (most commonly **Seminoma**), even if surgically corrected (Orchidopexy). * **Orchidopexy Timing:** Ideally performed between **6 to 12 months** of age to preserve fertility and allow for easier screening.

Question 1

Cutting of the pituitary stalk decreases all of the following hormones except?

Accepted Answer

Prolactin

Answer

ACTH

Answer

GH

Answer

FSH

Question 2

What is the imaging modality of choice for parathyroid pathology?

Accepted Answer

Tc 99 scan

Answer

CT scan

Answer

Gallium scan

Answer

Thallium scan

Question 3

All of the following are associated with insulin resistance except?

Accepted Answer

Calcific aortic valve disease

Answer

Acanthosis nigricans

Answer

Lipodystrophy

Answer

Gout

Question 4

A 48-year-old Caucasian man, diagnosed with diabetes 5 years ago, presents with palpitations. Physical examination reveals diffuse skin darkening and testicular atrophy. Laboratory studies show elevated liver function and elevated blood sugars. A liver biopsy shows significantly elevated iron levels, leading to a diagnosis of hereditary hemochromatosis. Which one of the following laboratory findings is seen in hereditary hemochromatosis?

Accepted Answer

Decreased total iron-binding capacity

Answer

Decreased serum ceruloplasmin

Answer

Decreased serum ferritin

Answer

Decreased serum iron

Question 5

Which of the following is responsible for fasting hypoglycemia?

Accepted Answer

Increased insulin level

Answer

Decreased insulin level

Answer

Increased glycogen

Answer

Increased glucagon in the liver

Question 6

In patients with significant atherosclerosis, which of the following conditions is increased approximately 100-fold in those with comorbid diabetes compared to non-diabetic patients?

Accepted Answer

Lower limb ischemia

Answer

Myocardial infarction

Answer

Ischemic stroke

Answer

Vertebrobasilar insufficiency

Question 7

Which of the following is true about primary aldosteronism?

Accepted Answer

Decreased K+

Answer

Pedal edema

Answer

Increased renin

Answer

Increased Na+

Question 8

Which test can confirm autoimmune thyroiditis in a patient?

Accepted Answer

Thyroid peroxidase antibody (TPO)

Answer

Antinuclear antibody

Answer

Thyroid uptake resin

Answer

Thyroid aspiration

Question 9

A female patient has elevated TSH and subnormal free T4. What is the likely diagnosis?

Accepted Answer

Primary hypothyroidism

Answer

Secondary hypothyroidism

Answer

Hyperthyroidism

Answer

Subclinical hypothyroidism

Question 10

Testicular descent is controlled by which factor?

Accepted Answer

Insulin-like factor 3 (INSL3)

Answer

RANKL

Answer

FSH

Answer

LH

Endocrinology — MCQs

Endocrinology — MCQs

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