Endocrinology Practice Questions

Q: A 45-year-old patient presents with muscle weakness and hyperpigmentation. Which condition is indicated by increased ACTH levels?

Addison's disease. ***Addison's disease*** - **Addison's disease** (primary adrenal insufficiency) leads to decreased cortisol production, which in turn causes a **compensatory increase in ACTH** [1]. - **High ACTH** stimulates melanocytes, resulting in characteristic **hyperpigmentation** along with symptoms of adrenal insufficiency like muscle weakness [1]. *Cushing's disease* - Cushing's disease is caused by an **ACTH-producing pituitary adenoma**, leading to **excessive cortisol production** [2]. - While ACTH levels are high, the primary presentation is typically **Cushingoid features** (e.g., central obesity, moon facies), and **hyperpigmentation** is less prominent than in Addison's disease. *Secondary hyperparathyroidism* - This condition involves **excessive parathyroid hormone (PTH)** secretion in response to hypocalcemia or vitamin D deficiency, unrelated to ACTH. - Symptoms are primarily related to **bone and mineral metabolism**, not muscle weakness nor hyperpigmentation caused by ACTH. *Pheochromocytoma* - A pheochromocytoma is a tumor of the adrenal medulla that secretes **catecholamines** (epinephrine and norepinephrine). - It causes symptoms like **hypertension, palpitations, and headaches**, and has no direct relationship with ACTH levels, muscle weakness, or hyperpigmentation.

Q: A 40-year-old female experiences muscle fatigue and cramping during exercise. Which metabolic condition is most likely contributing to her symptoms?

Hypokalemia. ***Hypokalemia*** - **Low potassium levels** can lead to impaired muscle contraction and relaxation, causing **muscle fatigue** and **cramping**, especially during exercise. - Potassium plays a crucial role in maintaining the **resting membrane potential** of muscle cells and nerve transmission. *Hypocalcemia* - Characterized by **decreased serum calcium**, which typically presents with **tetany**, **muscle spasms**, and paresthesias. - While it can cause muscle issues, the primary symptoms are often more severe and include excitability of nerves, not just fatigue and cramping. *Hyperkalemia* - Involves **elevated potassium levels**, which can result in **muscle weakness**, paralysis, and potentially life-threatening cardiac arrhythmias. - It does not typically manifest as exercise-induced fatigue and cramping, but rather a more generalized and persistent weakness. *Hypercalcemia* - Characterized by **elevated serum calcium** levels, which often lead to symptoms like **muscle weakness**, lethargy, and constipation. - It tends to cause generalized muscle weakness rather than specific exercise-induced fatigue and cramping.

Q: A 50-year-old woman with a history of thyroidectomy presents with hypocalcemia, and her serum calcium level is 6.5 mg/dL. What is the appropriate management plan?

Intravenous calcium gluconate. ***Intravenous calcium gluconate*** - A critically low serum calcium level of 6.5 mg/dL warrants **immediate correction** to prevent severe complications such as seizures or cardiac arrhythmias [1]. - **Intravenous calcium gluconate** is the preferred treatment for acute severe hypocalcemia due to its rapid onset of action. *Oral calcium supplementation* - **Oral calcium supplementation** is typically used for chronic, less severe hypocalcemia or as maintenance therapy after acute correction. - It would be **insufficiently rapid** to address the acute, symptomatic hypocalcemia in this patient. *Vitamin D supplementation* - **Vitamin D supplementation** is important for calcium absorption and metabolism, especially in conditions causing chronic hypocalcemia, but it has a slow onset of action [1]. - It is **not the primary treatment** for acute, severe hypocalcemia requiring immediate intervention. *Observation* - A serum calcium level of 6.5 mg/dL is **dangerously low** and can lead to life-threatening complications. - **Observation alone** is inappropriate and would put the patient at significant risk.

Q: A 40-year-old woman presents with fatigue, muscle weakness, and skin hyperpigmentation. Laboratory tests reveal hyponatremia and hyperkalemia. Which test would be most helpful in confirming the suspected diagnosis?

Morning cortisol level. Morning cortisol level - **Adrenal insufficiency** (Addison's disease) is characterized by reduced **cortisol** production, leading to symptoms like **fatigue**, **muscle weakness**, and **hyperpigmentation** [1], [3]. - **Hyponatremia** and **hyperkalemia** are also classic features of adrenal insufficiency due to deficient **aldosterone**, making a **low morning cortisol level** the most direct and crucial diagnostic test [1]. *Thyroid function tests* - While **fatigue** can be a symptom of **thyroid dysfunction**, this option does not explain the **hyperpigmentation**, **hyponatremia**, or **hyperkalemia**. - **Hypothyroidism** can cause **fatigue** and muscle weakness, but it typically presents with **constipation**, **weight gain**, and **dry skin**, not **hyperpigmentation** or electrolyte imbalances seen here [2]. *Serum aldosterone level* - A **low serum aldosterone level** would be consistent with adrenal insufficiency, but it is typically ordered *after* an initial screening test like morning cortisol or ACTH stimulation test confirms adrenal dysfunction [1]. - Measuring **aldosterone** alone is less specific for primary adrenal insufficiency, as it can also be affected by other conditions, and **cortisol** deficiency is typically part of the presenting picture. *Blood urea nitrogen* - **Blood urea nitrogen (BUN)** is a marker of **kidney function** and **hydration status**, which might be elevated in cases of dehydration or kidney injury associated with severe illness. - While electrolyte imbalances can indirectly affect kidney function, measuring **BUN** does not directly assess adrenal function or confirm the suspected diagnosis in this context.

Q: A 45-year-old woman with a history of hypertension is found to have a high plasma aldosterone level. Which condition is most likely present?

Primary hyperaldosteronism. ***Primary hyperaldosteronism*** - This condition is characterized by **excessive aldosterone production** directly from the adrenal glands, leading to **hypertension** and often **hypokalemia**. A high plasma aldosterone level in a hypertensive patient strongly points to this diagnosis. - The adrenal glands autonomously secrete aldosterone, uninhibited by the **renin-angiotensin system**. *Hypothyroidism* - This condition involves **insufficient thyroid hormone production**, which typically presents with symptoms such as fatigue, weight gain, and cold intolerance [1]. - While it can indirectly affect blood pressure, it does not directly cause primary elevation of **plasma aldosterone levels**. *Addison's disease* - This is a condition of **adrenal insufficiency**, meaning the adrenal glands produce **insufficient cortisol and aldosterone** [2]. - Therefore, patients with Addison's disease would have **low plasma aldosterone levels**, not high. *Pheochromocytoma* - This is a tumor of the adrenal medulla that secretes **catecholamines** (epinephrine and norepinephrine), leading to paroxysmal or sustained **hypertension**. - While it causes hypertension, it does not directly lead to primary elevation of **aldosterone levels** [3].

Q: A 45-year-old woman presents with fatigue and muscle weakness. Blood tests reveal hypercalcemia. What is the most likely cause of her symptoms?

Increased parathyroid hormone secretion. ***Increased parathyroid hormone secretion*** - **Primary hyperparathyroidism** is a common cause of hypercalcemia, often presenting with fatigue and muscle weakness due to the effects of high calcium levels [2], [3]. - **Parathyroid hormone (PTH)** directly increases serum calcium by promoting bone resorption, renal calcium reabsorption, and intestinal calcium absorption (indirectly via vitamin D activation) [1]. *Decreased bone resorption* - **Decreased bone resorption** would lead to lower serum calcium levels, as less calcium would be mobilized from bones into the bloodstream. - This option contradicts the clinical finding of **hypercalcemia**. *Increased calcitonin secretion* - **Calcitonin** lowers serum calcium by inhibiting bone resorption and increasing renal calcium excretion. - An increase in calcitonin would therefore cause **hypocalcemia**, not hypercalcemia. *Decreased renal calcium reabsorption* - **Decreased renal calcium reabsorption** would result in increased urinary calcium excretion and thus contribute to **hypocalcemia**, counteracting the observed hypercalcemia. - This mechanism is the opposite of what occurs in primary hyperparathyroidism, where PTH increases renal calcium reabsorption [1].

Q: A 35-year-old man presents with fatigue and salt craving. His laboratory results show low cortisol and aldosterone levels. Which condition is he most likely to have?

Addison's disease. ***Addison's disease*** - **Addison's disease** (primary adrenal insufficiency) is characterized by the destruction of the adrenal cortex, leading to **low cortisol and aldosterone levels** [1]. - Symptoms like **fatigue** and **salt craving** are classic manifestations due to mineralocorticoid deficiency (aldosterone) leading to sodium loss [1], [2]. *Cushing's syndrome* - **Cushing's syndrome** is caused by **excess cortisol**, leading to symptoms like central obesity, moon facies, and muscle weakness, which are opposite to the symptoms presented. - Aldosterone levels are typically normal or elevated, not low, unless there's a co-existing adrenal issue. *Hyperthyroidism* - **Hyperthyroidism** involves overproduction of **thyroid hormones**, leading to symptoms such as weight loss, heat intolerance, and palpitations. - It does not directly affect cortisol or aldosterone levels, nor does it typically cause salt craving. *Pheochromocytoma* - **Pheochromocytoma** is a tumor of the adrenal medulla that secretes **excess catecholamines** (epinephrine and norepinephrine). - This leads to symptoms such as hypertension, palpitations, and headaches, and does not directly cause low cortisol or aldosterone.

Q: A 30-year-old man complains of severe recurrent headaches and has been found to have elevated blood pressure. What diagnostic test is essential to evaluate the underlying cause?

24-hour urine test to evaluate for pheochromocytoma. 24-hour urine test to evaluate for pheochromocytoma - The combination of **recurrent severe headaches** and **elevated blood pressure** in a young adult is highly suspicious for a **pheochromocytoma**, a tumor of the adrenal medulla that secretes catecholamines. - A **24-hour urine test** for metanephrines and normetanephrines is the gold standard for diagnosing pheochromocytoma by measuring catecholamine metabolites. *Brain MRI for structural brain issues* - While headaches can be caused by structural brain issues, **elevated blood pressure** is not a primary symptom suggesting a brain tumor or other structural pathology as the direct cause of the hypertension [1]. - An MRI would be more relevant if there were focal neurological deficits, vision changes, or other red flags for intracranial pathology [1]. *Thyroid function tests for thyroid disorders* - **Hyperthyroidism** can cause hypertension, but it typically presents with other symptoms like weight loss, palpitations, tremor, and heat intolerance, which are not mentioned in this case. - While a general workup for hypertension might include thyroid function, it's not the essential test for the specific combination of severe headaches and hypertension in this context, especially given the paroxysmal nature implied by "recurrent severe headaches" [2]. *Electroencephalogram (EEG) for seizure disorders* - **Seizure disorders** are characterized by altered consciousness, convulsions, or other episodic neurological events, which are not described. - An EEG assesses brain electrical activity and would not be the initial or essential diagnostic test for evaluating the cause of recurrent headaches paired with elevated blood pressure.

Question 1

A 45-year-old patient presents with muscle weakness and hyperpigmentation. Which condition is indicated by increased ACTH levels?

Accepted Answer

Addison's disease

Answer

Cushing's disease

Answer

Secondary hyperparathyroidism

Answer

Pheochromocytoma

Question 2

A 40-year-old female experiences muscle fatigue and cramping during exercise. Which metabolic condition is most likely contributing to her symptoms?

Accepted Answer

Hypokalemia

Answer

Hypocalcemia

Answer

Hyperkalemia

Answer

Hypercalcemia

Question 3

A 45-year-old female presents with fatigue, hypotension, hyperpigmentation, hyponatremia, and hyperkalemia, and has a history of autoimmune disorders. What is the likely cause?

Accepted Answer

Adrenal insufficiency leading to cortisol and aldosterone deficiency

Answer

Hypothyroidism resulting in decreased metabolic rate and electrolyte imbalance

Answer

Parathyroid hormone dysregulation affecting calcium and sodium homeostasis

Answer

Pituitary adenoma causing ACTH hypersecretion and electrolyte disturbance

Question 4

A 50-year-old woman with a history of thyroidectomy presents with hypocalcemia, and her serum calcium level is 6.5 mg/dL. What is the appropriate management plan?

Accepted Answer

Intravenous calcium gluconate

Answer

Oral calcium supplementation

Answer

Vitamin D supplementation

Answer

Observation

Question 5

A 40-year-old woman presents with fatigue, muscle weakness, and skin hyperpigmentation. Laboratory tests reveal hyponatremia and hyperkalemia. Which test would be most helpful in confirming the suspected diagnosis?

Accepted Answer

Morning cortisol level

Answer

Thyroid function tests

Answer

Serum aldosterone level

Answer

Blood urea nitrogen

Question 6

A 40-year-old male with generalized anxiety disorder on an SSRI presents with fatigue, weight gain, and cold intolerance. Physical examination reveals dry skin and bradycardia. Laboratory results show elevated TSH and decreased FT4. Evaluate the situation and determine the treatment.

Accepted Answer

Add levothyroxine

Answer

Refer to an endocrinologist for further evaluation.

Answer

Add a triiodothyronine (T3) supplement.

Answer

Evaluate for SSRI-induced hypothyroidism and consider dose adjustment.

Question 7

A 45-year-old woman with a history of hypertension is found to have a high plasma aldosterone level. Which condition is most likely present?

Accepted Answer

Primary hyperaldosteronism

Answer

Hypothyroidism

Answer

Addison's disease

Answer

Pheochromocytoma

Question 8

A 45-year-old woman presents with fatigue and muscle weakness. Blood tests reveal hypercalcemia. What is the most likely cause of her symptoms?

Accepted Answer

Increased parathyroid hormone secretion

Answer

Decreased bone resorption

Answer

Increased calcitonin secretion

Answer

Decreased renal calcium reabsorption

Question 9

A 35-year-old man presents with fatigue and salt craving. His laboratory results show low cortisol and aldosterone levels. Which condition is he most likely to have?

Accepted Answer

Addison's disease

Answer

Cushing's syndrome

Answer

Hyperthyroidism

Answer

Pheochromocytoma

Question 10

A 30-year-old man complains of severe recurrent headaches and has been found to have elevated blood pressure. What diagnostic test is essential to evaluate the underlying cause?

Accepted Answer

24-hour urine test to evaluate for pheochromocytoma

Answer

Brain MRI for structural brain issues

Answer

Thyroid function tests for thyroid disorders

Answer

Electroencephalogram (EEG) for seizure disorders

Endocrinology — MCQs

Endocrinology — MCQs

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