Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1511: A 50-year-old male with poorly controlled diabetes presents with severe dehydration, metabolic acidosis, hyperglycemia, and ketonemia. What processes are likely occurring?

A. Lactic acidosis with increased renal ammonium production
B. Glucose-induced hyperkalemia with enhanced gluconeogenesis
C. Hyperosmolar hyperglycemic state with decreased insulin sensitivity
D. Diabetic ketoacidosis with ketoacid production (Correct Answer)

Explanation: ### Diabetic ketoacidosis with ketoacid production - The combination of **poorly controlled diabetes**, **severe dehydration**, **metabolic acidosis**, **hyperglycemia**, and **ketonemia** is pathognomonic for **diabetic ketoacidosis (DKA)** [1]. - In DKA, **insulin deficiency** leads to unchecked lipolysis, resulting in the production of **ketone bodies** (acetoacetate, beta-hydroxybutyrate, and acetone), which are strong acids, causing **metabolic acidosis** [2], [3]. ### Lactic acidosis with increased renal ammonium production - While metabolic acidosis is present, **lactic acidosis** would be characterized by elevated **lactate levels** and typically occurs in states of tissue hypoperfusion or hypoxia, which is not primarily indicated here. - **Increased renal ammonium production** is a compensatory mechanism for chronic metabolic acidosis, but it doesn't describe the primary pathological process. ### Glucose-induced hyperkalemia with enhanced gluconeogenesis - **Hyperkalemia** can occur in DKA due to acidosis and insulin deficiency, as H+ ions drive K+ out of cells while lack of insulin prevents K+ entry [2], [4]. However, "glucose-induced" hyperkalemia is not an accurate descriptor of the primary mechanism. - **Enhanced gluconeogenesis** does occur in DKA due to insulin deficiency and counter-regulatory hormones, but it's not the central process explaining the full clinical picture. ### Hyperosmolar hyperglycemic state with decreased insulin sensitivity - **Hyperosmolar hyperglycemic state (HHS)** also involves severe hyperglycemia and dehydration, but it is characterized by **minimal or no ketosis/acidosis**, distinguishing it from DKA [2]. - **Decreased insulin sensitivity** is a feature of type 2 diabetes and contributes to hyperglycemia in both DKA and HHS, but it doesn't explain the significant ketonemia and acidosis seen here.

Question 1512: A 25-year-old female with Type 1 diabetes is found unconscious, exhibiting rapid breathing and a fruity odor on her breath. What is the most likely diagnosis?

A. Hypoglycemia
B. Hyperosmolar hyperglycemic state
C. Diabetic ketoacidosis (Correct Answer)
D. Lactic acidosis

Explanation: ***Diabetic ketoacidosis*** - The combination of **unconsciousness**, **rapid breathing** (Kussmaul respirations), and a **fruity odor** on the breath (due to acetone) in a patient with Type 1 diabetes is highly indicative of DKA [1]. - DKA is characterized by **hyperglycemia**, **ketonemia**, and **metabolic acidosis**, often triggered by insulin deficiency [4]. *Hypoglycemia* - While hypoglycemia can cause unconsciousness, it typically does not present with rapid breathing or a fruity odor [3]. - **Rapid breathing** (Kussmaul respirations) is a compensatory mechanism for acidosis, and a **fruity breath** is due to ketones, which are absent in hypoglycemia [2]. *Hyperosmolar hyperglycemic state* - HHS typically presents with **severe hyperglycemia** and **dehydration**, leading to altered mental status, but it is more common in Type 2 diabetes [3]. - It does **not** involve significant ketosis or a fruity breath, and rapid breathing is less characteristic [1]. *Lactic acidosis* - Lactic acidosis can cause rapid breathing as a compensatory mechanism for acidosis and lead to unconsciousness. - However, it does **not** cause a fruity odor on the breath, which is specific to ketone production [4].

Question 1513: In evaluating the effectiveness of a new drug for treating hyperthyroidism, which laboratory finding would be the most indicative of drug efficacy?

A. Increased serum TSH levels
B. Decreased serum T3 and T4 levels (Correct Answer)
C. Increased serum T3 and T4 levels
D. Decreased serum TSH levels

Explanation: ***Decreased serum T3 and T4 levels*** - **Hyperthyroidism** is characterized by excessively high levels of thyroid hormones, primarily **T3** and **T4** [1]. - A drug's efficacy in treating hyperthyroidism would be directly reflected by a **reduction** in these elevated hormone levels, moving them towards the normal range. *Increased serum TSH levels* - In primary hyperthyroidism, the high levels of T3 and T4 typically **suppress** the release of **TSH** from the pituitary gland through negative feedback [1], [2]. - An **increase** in TSH, especially trending towards the normal range, combined with decreasing thyroid hormones, would suggest the thyroid gland is less hyperactive and TSH secretion is beginning to normalize in response. This would be a **secondary indicator** of drug efficacy. *Increased serum T3 and T4 levels* - An **increase** in serum T3 and T4 levels would indicate a **worsening** of hyperthyroidism or a lack of drug efficacy, as these are the hormones that are overproduced in this condition. - This finding would suggest the treatment is ineffective or that the dose is insufficient. *Decreased serum TSH levels* - **Decreased TSH levels** are characteristic of untreated hyperthyroidism due to negative feedback on the pituitary [1]. - If TSH levels remain low or decrease further, it suggests that the thyroid hormone levels are still high, and the drug is **not effectively reducing** thyroid hormone production.

Question 1514: A 30-year-old female is diagnosed with hyperthyroidism. Which effect is typically associated with this condition?

A. Increased sensitivity to catecholamines
B. Increased protein turnover
C. Increased basal metabolic rate (Correct Answer)
D. Decreased heat production

Explanation: Increased basal metabolic rate - **Thyroid hormones** (T3 and T4) directly stimulate cellular metabolism in almost all tissues, leading to an **increased basal metabolic rate** [1]. - This increased metabolic rate explains common symptoms of hyperthyroidism such as weight loss, heat intolerance, and increased appetite [1]. *Increased sensitivity to catecholamines* - Hyperthyroidism leads to an **increased number of beta-adrenergic receptors** in various tissues and can potentiate the effects of **catecholamines**, but it does not directly increase the sensitivity of existing receptors. - The symptoms mimicking sympathetic activation (e.g., tachycardia, tremors) are primarily due to this increased receptor expression [1]. *Increased protein turnover* - While thyroid hormones do influence **protein metabolism**, hyperthyroidism generally leads to a net **catabolic effect**, meaning protein breakdown (catabolism) often exceeds protein synthesis, resulting in muscle wasting. - Increased protein turnover can occur, but the net effect is often catabolic. *Decreased heat production* - Hyperthyroidism is associated with an **increased production of heat** due to the elevated metabolic rate [1]. - Patients typically experience **heat intolerance** and often sweat excessively, directly contradicting decreased heat production [1].

Question 1515: What is the most common cause of hypothyroidism in areas with adequate iodine intake?

A. Hashimoto's thyroiditis (Correct Answer)
B. Iodine deficiency
C. Thyroidectomy
D. Pituitary adenoma

Explanation: ***Hashimoto's thyroiditis*** - This is an **autoimmune disease** where the body's immune system attacks the thyroid gland, leading to chronic inflammation and eventual underproduction of thyroid hormones [1]. - It is the **most common cause of hypothyroidism** in regions with sufficient iodine intake [1]. *Iodine deficiency* - While iodine deficiency is the most common cause of hypothyroidism worldwide, the question specifically states "in areas with **adequate iodine intake**." - Lack of iodine hinders the thyroid's ability to produce thyroid hormones but is preventable through dietary supplementation. *Thyroidectomy* - This is the **surgical removal of all or part of the thyroid gland**, which can certainly lead to hypothyroidism if not enough thyroid tissue remains or if replacement therapy is inadequate. - However, it is an iatrogenic (medically induced) cause, not a naturally occurring disease process, and less common than autoimmune thyroiditis. *Pituitary adenoma* - A pituitary adenoma can cause **secondary hypothyroidism** by interfering with the pituitary gland's production of **Thyroid-Stimulating Hormone (TSH)** [1]. - This is a less common cause of hypothyroidism compared to primary thyroid disorders and is typically identified by additional symptoms related to pituitary dysfunction.

Question 1516: Which treatment is preferred for managing Graves' disease considering the risks of recurrence and complications?

A. Surgery is a definitive treatment but has higher complication rates.
B. Combination therapy with both treatments may provide better outcomes.
C. Radioactive iodine is not recommended due to potential recurrence.
D. Radioactive iodine is preferred due to its minimal invasiveness and effectiveness in treating hyperthyroidism. (Correct Answer)

Explanation: **Radioactive iodine is preferred due to its minimal invasiveness and effectiveness in treating hyperthyroidism.** - **Radioactive iodine (RAI)** therapy is a highly effective, minimally invasive treatment for **Graves' disease**, often leading to permanent **hypothyroidism**, which is managed with hormone replacement [1]. - It is particularly advantageous for patients who are not candidates for surgery or who have experienced recurrence after antithyroid medications [1]. *Surgery is a definitive treatment but has higher complication rates.* - While **thyroidectomy** is a definitive cure, it carries risks such as **hypoparathyroidism**, **vocal cord paralysis**, and general surgical complications [1]. - It is typically reserved for cases with **large goiters**, severe **ophthalmopathy**, or when other treatments are contraindicated. *Combination therapy with both treatments may provide better outcomes.* - **Combination therapy** (e.g., antithyroid drugs with RAI, or antithyroid drugs with surgery) is not a standard preferred approach for initial management. - Treatment choices usually involve a sequential approach or selection of a single definitive therapy based on patient factors and disease severity [1]. *Radioactive iodine is not recommended due to potential recurrence.* - **Radioactive iodine** actually has a very low recurrence rate for hyperthyroidism compared to antithyroid medications, as it destroys the overactive thyroid tissue. - The primary "recurrence" after RAI is the expected development of **hypothyroidism**, which is the desired outcome requiring lifelong hormone replacement, not a return of hyperthyroidism.

Question 1517: What is the most common cause of secondary hyperparathyroidism?

A. Vitamin D deficiency
B. Chronic kidney disease (Correct Answer)
C. Parathyroid adenoma
D. Calcium deficiency

Explanation: ***Chronic kidney disease*** - **Chronic kidney disease (CKD)** is the most common cause of secondary hyperparathyroidism due to impaired calcitriol synthesis and phosphate retention, leading to **hypocalcemia** [1], [3]. - The reduced GFR in CKD prevents efficient phosphate excretion, causing **hyperphosphatemia**, which directly stimulates PTH secretion and exacerbates hypocalcemia [3]. *Vitamin D deficiency* - While vitamin D deficiency can cause secondary hyperparathyroidism by leading to hypocalcemia, it is generally considered less common than CKD as the primary cause globally [2]. - Insufficient vitamin D impairs intestinal calcium absorption, triggering increased **PTH secretion** to maintain serum calcium levels [2], [4]. *Parathyroid adenoma* - A **parathyroid adenoma** is the most common cause of **primary hyperparathyroidism**, characterized by autonomous overproduction of PTH, leading to **hypercalcemia** [1]. - This condition involves a tumor of the parathyroid gland itself, differentiating it from secondary forms where PTH elevation is compensatory [1]. *Calcium deficiency* - While prolonged and severe dietary **calcium deficiency** can lead to secondary hyperparathyroidism due to chronic hypocalcemia, it is a less frequent cause compared to chronic kidney disease. - The body attempts to compensate for low calcium intake by increasing **PTH secretion** to mobilize calcium from bones and increase renal reabsorption [4].

Question 1518: In the context of Type 1 diabetes, which complication is primarily influenced by poor glycemic control?

A. Diabetic ketoacidosis (Correct Answer)
B. Hypothyroidism
C. Cushing's syndrome
D. Addison's disease

Explanation: ***Diabetic ketoacidosis*** - **Diabetic ketoacidosis (DKA)** is a life-threatening complication of **Type 1 diabetes** directly caused by severe **insulin deficiency** and **hyperglycemia** (poor glycemic control), leading to the body breaking down fat for energy and producing ketones [2]. - The lack of insulin prevents glucose from entering cells, escalating blood glucose levels and triggering the characteristic symptoms of **DKA** such as **acidosis**, **dehydration**, and **electrolyte imbalance** [3]. *Hypothyroidism* - **Hypothyroidism** is an **autoimmune condition** more frequently associated with Type 1 diabetes, but its onset and severity are not directly or primarily influenced by **glycemic control** [1]. - It results from the immune system attacking the **thyroid gland**, leading to reduced thyroid hormone production, independent of blood glucose levels. *Cushing's syndrome* - **Cushing's syndrome** is an **endocrine disorder** caused by prolonged exposure to high levels of **cortisol**, often due to a pituitary tumor or adrenal gland issues. - This condition can **induce hyperglycemia** and make glycemic control difficult, but it is not a direct complication of poor glycemic control in Type 1 diabetes; rather, it is a separate primary disorder. *Addison's disease* - **Addison's disease** is a rare, **autoimmune disorder** where the **adrenal glands** produce insufficient amounts of **cortisol and aldosterone**. It is sometimes seen in conjunction with Type 1 diabetes as part of a polyglandular autoimmune syndrome. - While it can be associated with Type 1 diabetes due to shared autoimmune mechanisms, it is an independent endocrine disorder and its development or progression is not linked to the patient's **glycemic control**.

Question 1519: A 65-year-old woman presents with hip pain, and an X-ray reveals osteopenia and femoral neck fractures. Which condition should be suspected?

A. Hyperparathyroidism
B. Rheumatoid arthritis
C. Osteoporosis (Correct Answer)
D. Osteomalacia

Explanation: ***Osteoporosis*** - **Osteopenia** and **femoral neck fractures** in an elderly woman are classic signs of **osteoporosis**, a condition characterized by reduced bone density and increased fracture risk. - The **hip fracture** is a common and severe complication of osteoporosis, often occurring spontaneously or with minimal trauma. *Hyperparathyroidism* - While hyperparathyroidism can cause **bone reabsorption** and osteopenia, it typically presents with other symptoms like **hypercalcemia**, kidney stones, or bone cysts (osteitis fibrosa cystica). - Femoral neck fractures are more directly indicative of widespread bone fragility, characteristic of osteoporosis, rather than the specific bone changes seen in hyperparathyroidism. *Rheumatoid arthritis* - This is an **inflammatory autoimmune disease** primarily affecting joints, leading to pain, swelling, and stiffness, particularly in the small joints. - Although it can lead to **secondary osteoporosis** due to inflammation, medication (corticosteroids), and immobility, the primary presentation is joint inflammation, not isolated osteopenia and fractures. *Osteomalacia* - **Osteomalacia** is characterized by defective **bone mineralization**, often due to **vitamin D deficiency**, leading to pliable, soft bones. - While it can cause bone pain and increased fracture risk, **osteopenia** (reduced bone *density*) and fragile fractures are more characteristic of osteoporosis, whereas osteomalacia often presents with specific radiographic findings like pseudofractures or Looser's zones.

Question 1520: Which clinical finding best supports the diagnosis of primary hyperparathyroidism?

A. Low serum calcium
B. High serum phosphorus
C. High serum calcium (Correct Answer)
D. Low serum magnesium

Explanation: High serum calcium - **Primary hyperparathyroidism** is characterized by excessive secretion of **parathyroid hormone (PTH)**, which leads to increased calcium reabsorption from bone and kidneys, resulting in **hypercalcemia** [1]. [4] - This is the most consistent and defining biochemical hallmark of the disease [2]. *Low serum calcium* - **Hypocalcemia** is indicative of conditions like **hypoparathyroidism** or vitamin D deficiency, where PTH levels are usually low or ineffective [3]. - It directly contradicts the overproduction of PTH seen in primary hyperparathyroidism, which aims to raise calcium levels. *High serum phosphorus* - In primary hyperparathyroidism, elevated PTH causes increased renal phosphate excretion, leading to **low or normal serum phosphorus** levels, not high [1]. [4] - **Hyperphosphatemia** is more characteristic of conditions like renal failure or hypoparathyroidism [3]. *Low serum magnesium* - While electrolyte imbalances can occur, **hypomagnesemia** is not a primary diagnostic criterion for hyperparathyroidism. - Severe hypomagnesemia can sometimes paradoxically reduce PTH secretion or its action, but it's not a direct consequence or diagnostic marker of primary hyperparathyroidism [3].

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

Practice Questions

Pituitary Disorders

Practice Questions

Calcium and Bone Metabolism

Practice Questions

Reproductive Endocrinology

Practice Questions

Lipid Disorders

Practice Questions

Endocrine Hypertension

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Neuroendocrine Tumors

Practice Questions

Endocrine Emergencies

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free