Endocrinology — MCQs

A 56-year-old man presents with increased thirst, increased urinary volume, and frequency, along with new symptoms of constipation and generalized aches and pains. He has no significant past medical history and a normal physical examination. Initial investigations reveal a normal complete blood count, fasting blood glucose, and urinalysis, with normal sodium, urea, and creatinine levels, but an elevated calcium level of 12.4 mg/dL (8.4-10.2 mg/dL). Further testing shows an elevated PTH level. What is the most likely cause of the patient's polyuria?

Q1669

Which of the following is NOT a criterion for primary hyperaldosteronism? a) Diastolic hypertension, b) Metabolic alkalosis, c) Low renin secretion, d) High aldosterone secretion.

Q1670

Which condition is primarily associated with tetany?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1661: Which of the following statements about testicular feminizing syndrome is incorrect?

A. Absent vagina (Correct Answer)
B. Absent ovary
C. Chromosome pattern 46 x Y
D. Absent uterus

Explanation: ### Absent vagina - This statement is incorrect. In **complete androgen insensitivity syndrome (CAIS)**, formerly known as testicular feminizing syndrome, individuals develop a **blind-ending vagina** that is typically shorter than normal, but it is not entirely absent. - The external genitalia are unambiguously female, leading to a female appearance, but the presence of testes and lack of a uterus/fallopian tubes are key features. *Absent ovary* - This statement is correct. Individuals with **complete androgen insensitivity syndrome (CAIS)** are **genetically male (46,XY)** and have **testes**, not ovaries. - The testes are usually undescended (intra-abdominal or inguinal) and produce androgens, but the body's cells are unresponsive to these hormones. *Chromosome pattern 46 x Y* - This statement is correct. **Complete androgen insensitivity syndrome (CAIS)** is characterized by a **46,XY karyotype**, meaning individuals are genetically male [1]. - Despite the male genotype, the inability to respond to androgens leads to female external phenotypic development. *Absent uterus* - This statement is correct. In **complete androgen insensitivity syndrome (CAIS)**, the **testes produce anti-Müllerian hormone (AMH)**, which causes the regression of the Müllerian ducts. - As a result, structures derived from the Müllerian ducts, such as the **uterus** and fallopian tubes, are absent.

Question 1662: A 32-year-old female who underwent whole-brain irradiation therapy following tumor growth in the brain is most likely to experience which hormone deficiency? (Select one correct answer)

A. Gonadotropin deficiency (Correct Answer)
B. Prolactin deficiency
C. ACTH deficiency
D. Growth hormone deficiency

Explanation: A 32-year-old female who underwent whole-brain irradiation therapy following tumor growth in the brain is most likely to experience which hormone deficiency? ***Gonadotropin deficiency*** - The **gonadotrophs** (producing **LH and FSH**) are among the most sensitive pituitary cells to radiation damage, often leading to early and significant deficiency [1]. - This is particularly common after **whole-brain irradiation** due to the pituitary's location within the radiation field [1]. *Prolactin deficiency* - **Lactotrophs** (producing **prolactin**) are generally considered to be among the *most resistant* cells to radiation-induced damage. - **Prolactin deficiency** is rare even after high doses of radiation and is usually only seen with extensive pituitary damage. *ACTH deficiency* - **Corticotrophs** (producing **ACTH**) are moderately sensitive to radiation, but usually less so than gonadotrophs [1]. - While possible, **ACTH deficiency** typically develops later than gonadotropin deficiency or requires higher doses of radiation [1]. *Growth hormone deficiency* - **Somatotrophs** (producing **GH**) are often the second most sensitive cells to radiation damage after gonadotrophs [1]. - While common after cranial irradiation, **gonadotropin deficiency** typically manifests earlier or with lower doses than GH deficiency [1].

Question 1663: Osteitis fibrosa cystica is associated with which of the following conditions?

A. Hyperparathyroidism (Correct Answer)
B. Hypoparathyroidism
C. Hypothyroidism
D. Hyperthyroidism

Explanation: ***Hyperparathyroidism*** - **Osteitis fibrosa cystica** is a classic bone manifestation of severe, chronic **hyperparathyroidism**, characterized by increased osteoclastic activity. - This condition results in the replacement of normal bone with **fibrous tissue** and **cysts**, often leading to bone pain, fractures, and deformities. *Hypoparathyroidism* - **Hypoparathyroidism** is characterized by low parathyroid hormone (PTH) levels and **hypocalcemia**, which typically leads to increased bone density, not bone degradation. - Its manifestations include muscle cramps, seizures, and tetany, without the bone lesions seen in osteitis fibrosa cystica. *Hypothyroidism* - **Hypothyroidism** is a state of thyroid hormone deficiency, affecting metabolism and growth but not directly causing osteitis fibrosa cystica. - It can lead to slowed bone turnover and delayed growth in children, but not the specific bone lesions associated with parathyroid dysfunction. *Hyperthyroidism* - **Hyperthyroidism** can cause increased bone turnover and **osteoporosis** due to accelerated bone resorption, but it does not lead to the distinct fibrous and cystic bone changes of osteitis fibrosa cystica. - Its effects on bone are generally a diffuse reduction in bone mineral density rather than specific lytic lesions or brown tumors.

Question 1664: Which of the following hormones are raised in Prader-Willi syndrome?

A. Follicle Stimulating Hormone (FSH)
B. Ghrelin (Correct Answer)
C. Luteinizing Hormone (LH)
D. Growth Hormone (GH)

Explanation: Ghrelin - Ghrelin levels are typically elevated in patients with Prader-Willi syndrome, contributing to their characteristic hyperphagia and obesity. - This increased ghrelin secretion leads to a perpetual feeling of hunger and an insatiable appetite. Luteinizing Hormone (LH) - LH levels are often low in individuals with Prader-Willi syndrome, contributing to hypogonadism [1]. - This deficiency is part of the broader endocrine dysfunction seen in the syndrome. Follicle Stimulating Hormone (FSH) - FSH levels are generally low in Prader-Willi syndrome, mirroring the low LH levels and indicating hypogonadotropic hypogonadism [1]. - This hormonal imbalance leads to incomplete sexual development and infertility. Growth Hormone (GH) - Growth hormone levels are typically low or deficient in Prader-Willi syndrome, contributing to short stature and abnormal body composition. - GH deficiency is a common feature, often necessitating exogenous growth hormone therapy.

Question 1665: Which is the most common cause of death in type 1 diabetes mellitus?

A. Infections
B. Myocardial disease (Correct Answer)
C. Stroke
D. Kidney disease

Explanation: ***Myocardial disease*** - **Cardiovascular disease**, particularly **myocardial infarction** and **heart failure**, is the leading cause of death in both type 1 and type 2 diabetes due to accelerated atherosclerosis. - This increased risk stems from chronic hyperglycemia, dyslipidemia, hypertension, and inflammation associated with uncontrolled diabetes. *Kidney disease* - While **diabetic nephropathy** is a serious long-term complication of type 1 diabetes and can lead to end-stage renal disease, it is not the most common direct cause of death. - Patients with kidney disease often eventually succumb to **cardiovascular complications** that are often exacerbated by renal dysfunction. *Stroke* - **Ischemic stroke** is a significant complication of diabetes due to increased risk of atherosclerosis affecting cerebral vessels, but it occurs less frequently than myocardial disease. - Stroke is a critical cause of **morbidity** and **disability** but ranks below myocardial disease in overall mortality in diabetic patients. *Infections* - Individuals with diabetes are more susceptible to severe and atypical infections due to impaired immune function. - While infections can lead to significant illness and death, they are not the leading cause of mortality compared to macrovascular complications like myocardial disease.

Question 1666: All of the following statements regarding diabetes mellitus are true, except one:

A. Insulin levels may be decreased in patients with Type II Diabetes mellitus
B. Insulin is essential to reverse Diabetic Ketoacidosis
C. Intravenous Insulin is administered as a sliding scale in the hospital setting
D. Insulin is never used in Type II Diabetes mellitus (Correct Answer)

Explanation: ***Insulin is never used in Type II Diabetes mellitus*** - This statement is incorrect because insulin therapy is a common treatment for Type II Diabetes mellitus, particularly when **oral medications** and **lifestyle modifications** are insufficient to control blood glucose levels. [1] - Many patients with Type II DM eventually experience pancreatic beta-cell dysfunction, necessitating **exogenous insulin** to achieve glycemic targets. [1] [2] *Insulin levels may be decreased in patients with Type II Diabetes mellitus* - While Type II DM is initially characterized by **insulin resistance** and compensatory hyperinsulinemia, over time the **pancreatic beta cells** can fail, leading to reduced insulin production. [2] - This decline in insulin secretion necessitates insulin therapy in later stages of the disease. *Insulin is essential to reverse Diabetic Ketoacidosis* - **Diabetic Ketoacidosis (DKA)** is a life-threatening complication primarily of Type 1 DM (but can occur in Type 2 DM) characterized by **severe insulin deficiency**, hyperglycemia, ketosis, and acidosis. [2] [3] - **Insulin therapy** is critical to stop ketogenesis, promote glucose uptake, and correct metabolic acidosis. *Intravenous Insulin is administered as a sliding scale in the hospital setting* - A **sliding scale insulin regimen** involves administering insulin doses based on current blood glucose readings, often used in hospital settings for both Type 1 and Type 2 DM patients. - While often used, it is increasingly being replaced by **basal-bolus regimens** for better glycemic control. [1]

Question 1667: A known patient with renal stone disease, who developed a pathological fracture, abdominal pain, and certain psychiatric symptoms, should be investigated for.

A. Polycystic kidney disease
B. Renal tubular acidosis (RTA)
C. Primary hyperparathyroidism (Correct Answer)
D. Paget's disease of bone (osteitis deformans)

Explanation: ***Primary hyperparathyroidism*** - The combination of **renal stones** ("stones"), **pathological fractures** ("bones"), and **psychiatric symptoms** ("groans" and "moans") is a classic presentation of **primary hyperparathyroidism** due to hypercalcemia [1], [2]. - **Elevated parathyroid hormone (PTH)** leads to increased calcium resorption from bones and reabsorption in the kidneys, causing the described symptoms [1], [2]. *Polycystic kidney disease* - This genetic disorder is characterized by **cysts in the kidneys**, which can lead to renal failure and hypertension, but typically not pathological fractures or hypercalcemia-related psychiatric symptoms. - While **renal stones can occur**, the other systemic features point away from this diagnosis. *Renal tubular acidosis (RTA)* - RTA is a group of disorders where the kidneys fail to reabsorb or secrete acids properly, leading to **metabolic acidosis** and sometimes **nephrocalcinosis** (renal stones). - It does not typically cause hypercalcemia-related pathological fractures or psychiatric symptoms. *Paget's disease of bone (osteitis deformans)* - This disorder is characterized by **disorganized bone remodeling**, leading to localized areas of enlarged and weakened bone, which can cause fractures and bone pain. - While it affects bones, it does not typically cause **renal stones** or the **hypercalcemia-related psychiatric symptoms** seen in this patient [1].

Question 1668: A 56-year-old man presents with increased thirst, increased urinary volume, and frequency, along with new symptoms of constipation and generalized aches and pains. He has no significant past medical history and a normal physical examination. Initial investigations reveal a normal complete blood count, fasting blood glucose, and urinalysis, with normal sodium, urea, and creatinine levels, but an elevated calcium level of 12.4 mg/dL (8.4-10.2 mg/dL). Further testing shows an elevated PTH level. What is the most likely cause of the patient's polyuria?

A. Renal tubular acidosis due to hypercalcemia
B. Chronic renal failure secondary to hypercalcemia
C. Nephrogenic diabetes insipidus due to hypercalcemia (Correct Answer)
D. Increased renal excretion of water due to PTH action

Explanation: ***Nephrogenic diabetes insipidus due to hypercalcemia*** - **Hypercalcemia** can induce **nephrogenic diabetes insipidus** by impairing the kidney's ability to respond to **vasopressin (ADH)** [3], leading to increased urinary volume and frequency. - The elevated **PTH** confirms **primary hyperparathyroidism** [1], a common cause of hypercalcemia [4], which then drives the polyuria through this mechanism. *Renal tubular acidosis due to hypercalcemia* - While hypercalcemia can sometimes be associated with **renal tubular acidosis**, the primary symptom of **polyuria** is more directly explained by impaired ADH action rather than a specific acid-base disorder. - Renal tubular acidosis typically involves systemic **acid-base imbalances** and is not the most direct cause for the osmotic diuresis seen with polyuria in hypercalcemia. *Chronic renal failure secondary to hypercalcemia* - While severe and prolonged hypercalcemia can eventually lead to **chronic kidney disease** and **renal insufficiency** [2], the symptoms presented, particularly the prominent **polyuria** (increased urinary volume), suggest an immediate functional impairment of water reabsorption, rather than significant structural damage indicated by chronic renal failure. - The normal **creatinine** and **urea** levels argue against established chronic renal failure. *Increased renal excretion of water due to PTH action* - **PTH** primarily regulates **calcium** and **phosphate** metabolism, and its direct action does not significantly increase renal water excretion [4]. - The polyuria observed is an indirect effect of **PTH-induced hypercalcemia**, which then compromises the renal concentrating ability, not a direct action of PTH on water excretion.

Question 1669: Which of the following is NOT a criterion for primary hyperaldosteronism? a) Diastolic hypertension, b) Metabolic alkalosis, c) Low renin secretion, d) High aldosterone secretion.

A. Low renin secretion
B. High aldosterone secretion
C. Diastolic hypertension (Correct Answer)
D. Metabolic alkalosis

Explanation: ***Diastolic hypertension*** - While hypertension, including diastolic hypertension, is a common manifestation of primary hyperaldosteronism due to **sodium and water retention**, it is a *result* of the condition, not a direct diagnostic criterion or physiological hallmark [2]. - The core diagnostic criteria focus on the **renin-aldosterone axis** and metabolic derangements indicative of excessive mineralocorticoid activity. *Low renin secretion* - This is a key diagnostic feature of **primary hyperaldosteronism**, as high aldosterone levels suppress renin release through a negative feedback loop [2]. - The **aldosterone-to-renin ratio** is a crucial screening test for this condition. *High aldosterone secretion* - This is the **defining characteristic** of primary hyperaldosteronism, driven by an adrenal adenoma or bilateral adrenal hyperplasia. - Elevated aldosterone levels lead to increased **sodium reabsorption** and **potassium excretion** [1]. *Metabolic alkalosis* - This often develops due to increased **potassium and hydrogen ion excretion** in the renal tubules, spurred by high aldosterone levels [1]. - The resulting **hypokalemia** and alkalosis contribute to the clinical picture; primary hyperaldosteronism (Conn's syndrome) is a classical cause of normovolaemic metabolic alkalosis [3].

Question 1670: Which condition is primarily associated with tetany?

A. None of the options
B. Hyperparathyroidism
C. Hypercalcemia
D. Hypocalcemia (Correct Answer)

Explanation: ***Hypocalcemia*** - **Tetany** is a neuromuscular hyperexcitability state resulting from critically low levels of **ionized calcium** in the extracellular fluid [2]. - Reduced extracellular calcium increases neuronal membrane excitability, leading to spontaneous and repetitive nerve discharges and muscle contractions. *Hypercalcemia* - **Hypercalcemia** refers to elevated calcium levels, which *decreases* neuromuscular excitability. - Symptoms typically involve **fatigue, weakness, constipation, and kidney stones**, rather than tetany [1]. *Hyperparathyroidism* - **Primary hyperparathyroidism** is a common cause of **hypercalcemia** due to increased PTH secretion [3]. - Therefore, it leads to symptoms associated with high calcium, not low calcium and tetany. *None of the options* - This option is incorrect because **hypocalcemia** is a well-established cause of tetany.

Practice by Chapter

Diabetes Mellitus

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Thyroid Disorders

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Adrenal Gland Disorders

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Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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