Endocrinology Practice Questions

Q: Which of the following is true for Klinefelter's syndrome?

Increased arm span and height. Explanation: **Klinefelter’s Syndrome (47,XXY)** is the most common sex chromosome disorder causing primary hypogonadism in males. **Why Option B is Correct:** Patients with Klinefelter’s syndrome exhibit **eunuchoid body proportions** [1]. This occurs because the deficiency in testosterone leads to delayed closure of the epiphyseal plates. Growth continues under the influence of growth hormone, specifically affecting the long bones. Consequently, the **arm span exceeds the total height** (usually by >2 cm), and the lower segment (pubis to floor) is longer than the upper segment (crown to pubis) [1]. **Analysis of Incorrect Options:** * **A (45,X):** This is the karyotype for **Turner Syndrome**, which presents in phenotypic females with short stature and streak ovaries [3, 5]. Klinefelter’s is typically **47,XXY**. * **C (Attains puberty normally):** While initial pubertal changes may begin, patients fail to complete maturation. They develop **hypergonadotropic hypogonadism** due to testicular failure, leading to poor development of secondary sexual characteristics [1, 4]. * **D (Normal testes and genitalia):** A hallmark of Klinefelter’s is **small, firm testes** (usually <2 cm or <6 mL volume) due to hyalinization and fibrosis of the seminiferous tubules [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Laboratory Findings:** Low Testosterone, **Increased LH and FSH** (due to loss of feedback inhibition), and Increased Estradiol [1]. * **Clinical Features:** Gynecomastia (increased risk of male breast cancer), infertility (azoospermia), and mild intellectual disability [1, 4]. * **Histology:** Absence of germ cells and **Leydig cell hyperplasia** (clumping). * **Barr Body:** Positive (due to the extra X chromosome).

Q: Which of the following is NOT a feature of Kallmann syndrome?

Mental retardation. **Explanation:** **Kallmann Syndrome** is a form of **hypogonadotropic hypogonadism** (low FSH/LH) associated with **anosmia** (loss of smell). It results from the failure of GnRH-secreting neurons and olfactory neurons to migrate from the olfactory placode to the hypothalamus during development. **Why Mental Retardation is the Correct Answer:** Mental retardation is **not** a characteristic feature of Kallmann syndrome. While the condition involves developmental migration defects, cognitive function is typically preserved. If a patient presents with hypogonadotropic hypogonadism and mental retardation, clinicians should consider other syndromes like **Prader-Willi Syndrome** or **Laurence-Moon-Biedl Syndrome**. **Analysis of Incorrect Options:** * **Micropenis (A):** Due to low testosterone levels during the critical period of fetal development, males often present with a micropenis and cryptorchidism. * **Primary Amenorrhea (B):** In females, the lack of GnRH leads to low estrogen levels and a failure to initiate puberty, resulting in primary amenorrhea and absent secondary sexual characteristics. * **Mirror Movements (C):** Also known as **bimanual synkinesis**, these are involuntary movements of one hand that mimic the voluntary movements of the other. This is a recognized neurological association in Kallmann syndrome (often linked to *KAL1* gene mutations). **High-Yield Clinical Pearls for NEET-PG:** 1. **Inheritance:** Most commonly X-linked recessive (*KAL1* gene), but can be Autosomal Dominant (*FGFR1*) or Autosomal Recessive. 2. **Key Triad:** Hypogonadotropic hypogonadism + Anosmia/Hyposmia + Midline defects. 3. **Associated Features:** Renal agenesis (unilateral), cleft lip/palate, and sensorineural deafness. 4. **Diagnosis:** Low Testosterone/Estrogen with low or inappropriately normal FSH/LH; MRI may show absent/hypoplastic olfactory bulbs.

Q: A child presents with features of hyperparathyroidism. All of the following are true regarding this condition except:

Raised serum phosphorus. In **Primary Hyperparathyroidism**, the fundamental pathology is the overproduction of Parathyroid Hormone (PTH), usually due to a parathyroid adenoma. Understanding the physiological actions of PTH is key to solving this question. ### Why "Raised serum phosphorus" is the Correct Answer (The Exception) PTH acts directly on the proximal convoluted tubules of the kidney to **inhibit the reabsorption of phosphate**, leading to increased urinary excretion (phosphaturia). Consequently, the hallmark of hyperparathyroidism is **hypophosphatemia** (low serum phosphorus), not hyperphosphatemia. ### Explanation of Incorrect Options * **A. Raised serum calcium:** PTH increases serum calcium by stimulating osteoclastic bone resorption, increasing renal tubular reabsorption of calcium, and enhancing intestinal calcium absorption (via Vitamin D activation). Hypercalcemia is the most consistent finding. * **C. Raised alkaline phosphatase (ALP):** Increased PTH leads to high bone turnover. ALP is a marker of osteoblastic activity which occurs secondary to increased osteoclastic bone resorption. * **D. Resorption of minerals from bones:** PTH directly stimulates osteoclasts to break down the bone matrix, releasing calcium and phosphorus into the bloodstream. ### High-Yield NEET-PG Pearls * **Classic Triad:** Hypercalcemia, Hypophosphatemia, and Hypercalciuria (despite increased renal reabsorption, the filtered load of calcium exceeds the kidney's capacity). * **Radiological Sign:** Subperiosteal bone resorption, most classically seen on the radial aspect of the middle phalanges. * **Osteitis Fibrosa Cystica:** The end-stage bone manifestation characterized by "Brown tumors." * **Mnemonic for Symptoms:** "Stones (renal), bones (pain/fractures), groans (abdominal pain/constipation), and psychic overtones (depression/confusion)."

Q: A 39-year-old man presents to his physician with the complaint of loss of peripheral vision. The subsequent magnetic resonance imaging (MRI) scan demonstrates what abnormality?

Pituitary adenoma. ***Pituitary adenoma*** - Loss of **peripheral vision** (bitemporal hemianopia) is the classic presentation of **pituitary adenoma** compressing the **optic chiasm**. - MRI typically shows a **sellar/suprasellar mass** with **signal heterogeneity** and possible **suprasellar extension** in macroadenomas. *Cerebral atrophy* - Presents with **generalized brain volume loss** and **ventricular enlargement**, not focal visual field defects. - Associated with **dementia** and **cognitive decline**, not isolated peripheral vision loss. *Optic glioma* - Causes **monocular visual loss** or **central scotomas**, not bilateral peripheral vision loss. - MRI shows **fusiform enlargement** of the **optic nerve** with **T2 hyperintensity**, not sellar masses. *Pontine hemorrhage* - Results in **quadriplegia**, **coma**, and **pinpoint pupils** due to brainstem involvement. - MRI demonstrates **hyperacute hemorrhage** in the **pons** with surrounding **edema**, not visual field defects.

Q: What is the most common cause of hyperthyroidism?

Graves' disease. **Explanation:** **Graves’ disease** is the most common cause of hyperthyroidism worldwide, accounting for approximately 60–80% of all cases [2]. It is an autoimmune disorder characterized by the production of **Thyroid Stimulating Immunoglobulins (TSI)** [1]. These autoantibodies act as agonists to the TSH receptor on thyroid follicular cells, leading to continuous stimulation of the gland, excessive synthesis of thyroid hormones (T3 and T4), and diffuse glandular enlargement [1], [2]. **Analysis of Incorrect Options:** * **Thyroid hyperplasia (A):** While Graves' disease involves diffuse hyperplasia of the thyroid gland, "hyperplasia" is a pathological description rather than a specific disease entity. In the context of hyperthyroidism, the underlying autoimmune process (Graves') is the primary clinical cause [1]. * **Thyroid adenoma (B):** Specifically, a "Toxic Adenoma" (Plummer’s disease) is a common cause of hyperthyroidism, but it ranks second to Graves' disease. It involves a solitary hyperfunctioning nodule that acts independently of TSH [3]. * **Thyroid carcinoma (C):** Most thyroid cancers (like papillary or follicular) are "cold" nodules and do not produce excess thyroid hormone. Hyperthyroidism due to functioning thyroid carcinoma is extremely rare. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad of Graves’:** Hyperthyroidism, Diffuse Goiter, and Ophthalmopathy (Exophthalmos) [2]. * **Specific Sign:** **Pretibial Myxedema** (Dermopathy) is pathognomonic for Graves’ disease [1]. * **Diagnosis:** Low TSH, High Free T4, and **diffuse increased uptake** on Radioactive Iodine Uptake (RAIU) scan. * **Antibody:** Anti-TSH receptor antibody (TRAb) is the most specific marker [1].

Q: Diabetes control is best monitored by?

HbA1c. **Explanation:** **HbA1c (Glycated Hemoglobin)** is the gold standard for monitoring long-term glycemic control in diabetic patients [3]. It reflects the average blood glucose levels over the preceding **8 to 12 weeks** (the average lifespan of a red blood cell) [4]. The underlying medical concept is the **non-enzymatic glycosylation** of hemoglobin. Glucose molecules attach to the N-terminal valine of the beta chain of hemoglobin A at a rate proportional to the glucose concentration in the blood [3]. Because this process is irreversible, HbA1c provides a stable "weighted average" that is not affected by recent meals, exercise, or acute stress [4]. **Why other options are incorrect:** * **Serum Glucose & Post-Prandial Blood Glucose (PPBG):** These provide only a "snapshot" of the blood sugar at a specific moment [1]. They are highly variable and can be influenced by the patient's last meal, physical activity, or medication adherence on the day of the test [2]. They are useful for acute management but not for assessing overall long-term control. * **HbA2c:** This is a distractor. HbA2 is a normal variant of hemoglobin (comprising two alpha and two delta chains), but "HbA2c" is not a standard clinical marker used for monitoring diabetes. **Clinical Pearls for NEET-PG:** * **Target HbA1c:** For most non-pregnant adults, the goal is **<7%** [5]. * **Falsely Low HbA1c:** Seen in conditions with high RBC turnover (e.g., Hemolytic anemia, recent blood transfusion, pregnancy, or treatment with Erythropoietin). * **Falsely High HbA1c:** Seen in conditions that prolong RBC lifespan (e.g., Iron deficiency anemia, Vitamin B12 deficiency, or Splenectomy). * **Fructosamine Test:** Used to monitor control over a shorter period (**2–3 weeks**) in patients where HbA1c is unreliable (e.g., Hemoglobinopathies).

Q: All of the following are features of acromegaly, except?

Low serum phosphate. In Acromegaly, excessive Growth Hormone (GH) leads to characteristic metabolic and biochemical changes. The correct answer is **D (Low serum phosphate)** because Acromegaly actually causes **hyperphosphatemia**, not low phosphate. [1] ### Why Option D is correct: Growth hormone has a direct effect on the kidneys, where it **increases the renal tubular reabsorption of phosphate**. This leads to elevated serum phosphate levels in patients with active acromegaly. [1] Therefore, "Low serum phosphate" is the incorrect feature. ### Why other options are incorrect: * **A. Glucose intolerance:** GH is a potent counter-regulatory hormone that antagonizes insulin action and increases hepatic gluconeogenesis. [1] Approximately 50% of patients have glucose intolerance, and 10-15% develop overt Diabetes Mellitus. * **B. Nonsuppressibility of GH:** This is the physiological hallmark. In healthy individuals, an oral glucose load (75g) suppresses GH to <1 µg/L. In acromegaly, the autonomous secretion from a pituitary adenoma fails to suppress [2], which is the **Gold Standard diagnostic test**. * **C. Raised Somatomedin C (IGF-1):** GH stimulates the liver to produce IGF-1 (Somatomedin C). Since GH secretion is pulsatile, a single GH measurement is unreliable; however, IGF-1 levels are stable and serve as the **best screening test**. [3] ### NEET-PG High-Yield Pearls: * **Best Screening Test:** Serum IGF-1 levels. * **Confirmatory Test:** Oral Glucose Tolerance Test (OGTT) for GH suppression. * **Most Common Cause:** Pituitary Adenoma (Somatotroph adenoma). [3] * **Radiological Investigation of Choice:** MRI of the Brain (Sella turcica). * **Metabolic Associations:** Hypercalciuria (due to increased Vitamin D activation) and Hyperphosphatemia. [1]

Question 1

Which of the following is true for Klinefelter's syndrome?

Accepted Answer

Increased arm span and height

Answer

45,X

Answer

Attains puberty normally

Answer

Normal testes and genitalia

Question 2

Which of the following is NOT a feature of Kallmann syndrome?

Accepted Answer

Mental retardation

Answer

Micropenis

Answer

Primary amenorrhea

Answer

Mirror movements of the hands

Question 3

All of the following are helpful in the initial treatment of severe hypercalcemia associated with hyperparathyroidism except?

Accepted Answer

Glucocorticoids

Answer

Hydration with saline

Answer

Forced diuresis with loop diuretics

Answer

Pamidronate

Question 4

A patient underwent bilateral adrenalectomy for bilateral pheochromocytoma. One day later, the patient developed lethargy, fatigue, low blood pressure, and a normal pulse. There are no signs of volume deficit. What is the likely course?

Accepted Answer

Addisonian Crisis

Answer

SIADH

Answer

Diabetes Insipidus (DI)

Answer

Cerebral Salt Wasting Syndrome

Question 5

A child presents with features of hyperparathyroidism. All of the following are true regarding this condition except:

Accepted Answer

Raised serum phosphorus

Answer

Raised serum calcium

Answer

Raised alkaline phosphatase

Answer

Resorption of minerals from bones

Question 6

A 39-year-old man presents to his physician with the complaint of loss of peripheral vision. The subsequent magnetic resonance imaging (MRI) scan demonstrates what abnormality?

Accepted Answer

Pituitary adenoma

Answer

Cerebral atrophy

Answer

Optic glioma

Answer

Pontine hemorrhage

Question 7

What is the most common cause of hyperthyroidism?

Accepted Answer

Graves' disease

Answer

Thyroid hyperplasia

Answer

Thyroid adenoma

Answer

Thyroid carcinoma

Question 8

Diabetes control is best monitored by?

Accepted Answer

HbA1c

Answer

Serum glucose

Answer

Post prandial blood glucose

Answer

HbA2c

Question 9

A 40-year-old non-alcoholic male patient presented with jaundice, lethargy, arthralgia, skin pigmentation, loss of libido, polyuria, polydipsia, and exertional dyspnea. On examination, hepatosplenomegaly, increased pigmentation, spider angiomas, arthropathy, ascites, loss of body hair, and testicular atrophy were noted. Liver function tests were deranged, and insulin levels were raised. Liver biopsy was performed. The patient had no history of long-term medication intake. Iron studies revealed: Plasma iron - 200 microgm/dL, TIBC - 300 microgm/dL, Transferrin saturation - 90%, Serum ferritin - 5000 microgm/L, Liver iron - 10000 microgm/gm of dry weight, Hepatic iron index - 3. What is the most common mutation seen in this condition?

Accepted Answer

C282Y

Answer

H63D

Answer

H62D

Answer

C283Y

Question 10

All of the following are features of acromegaly, except?

Accepted Answer

Low serum phosphate

Answer

Glucose intolerance

Answer

Nonsuppressibility of growth hormone by glucose ingestion

Answer

Raised levels of plasma somatomedin C

Endocrinology — MCQs

Endocrinology — MCQs

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