Endocrinology Practice Questions

Q: Which one of the following is the earliest manifestation of Cushing's syndrome?

Loss of diurnal variation. ***Loss of diurnal variation*** - The **normal diurnal rhythm** of cortisol secretion, with higher levels in the morning and lower levels at night, is one of the earliest markers to be disrupted in Cushing's syndrome [2]. - This disruption leads to an inappropriate elevation of cortisol during the late evening and early morning, which can be detected by **midnight salivary cortisol** levels [2]. *Increased ACTH* - An increase in **ACTH** (adrenocorticotropic hormone) is only characteristic of **ACTH-dependent Cushing's syndrome** (e.g., Cushing's disease or ectopic ACTH production) [3]. - In cases of **ACTH-independent Cushing's syndrome** (e.g., adrenal adenoma), ACTH levels would be suppressed, not increased [2], [3]. *Increased plasma cortisol* - While increased plasma cortisol is a hallmark of Cushing's syndrome, a **single elevated plasma cortisol level** is not the earliest or most reliable indicator [1]. - Cortisol levels can fluctuate due to stress, and a lack of **diurnal variation** or failure to suppress with dexamethasone is more specific for early diagnosis [1]. *Increased urinary metabolites of cortisol* - Measuring **24-hour urinary free cortisol** (UFC) is a common diagnostic test for Cushing's syndrome, reflecting the total amount of unbound cortisol excreted over a day [1]. - However, the disruption of the **diurnal rhythm** often precedes a significant and consistently high elevation in total 24-hour urinary free cortisol.

Q: Which of the following statements about pheochromocytoma is true?

Arises from chromaffin cells of adrenal medulla. ***Arises from chromaffin cells of adrenal medulla*** - **Pheochromocytomas** are rare neuroendocrine tumors that develop from **chromaffin cells** found in the adrenal medulla. - These cells are responsible for synthesizing and secreting **catecholamines**, explaining the characteristic symptoms of pheochromocytoma. *Bilateral in 20% of all cases* - While pheochromocytomas can be bilateral, this occurs in about **10% of cases**, mostly associated with genetic syndromes like **MEN 2**. - A higher percentage of bilaterality is seen in **familial forms** of the disease, but not in all cases. *Hypotension rules out pheochromocytoma* - Although **hypertension** is a hallmark symptom, **hypotension** can occur, particularly **orthostatic hypotension** due to volume depletion and impaired vasoconstriction. - Rarely, **pheochromocytoma crisis** can present with **shock** due to massive catecholamine release and subsequent myocardial dysfunction or vasoplegia. *Almost always a malignant tumor* - Most pheochromocytomas are **benign**; only about **10-15%** are malignant. - Malignancy is suggested by the presence of **metastatic disease**, as histology alone cannot reliably differentiate between benign and malignant forms.

Q: Which one of the following is the MOST common complication of diabetes mellitus?

Peripheral Neuropathy. ***Peripheral Neuropathy*** - **Peripheral neuropathy** is the most common complication of diabetes, affecting up to 50% of patients with long-standing disease [1]. - It results from **nerve damage** due to chronic hyperglycemia, leading to symptoms like pain, numbness, and weakness, primarily in the extremities [1]. *Diabetic Retinopathy* - While a common microvascular complication, **diabetic retinopathy** occurs in about one-third of diabetic patients and is not as prevalent as peripheral neuropathy [2]. - It involves damage to the **blood vessels of the retina** and can lead to vision loss. *Diabetic Nephropathy* - **Diabetic nephropathy** is a serious complication affecting approximately 20-40% of diabetic patients, leading to kidney disease. - It is characterized by progressive **kidney damage** and can lead to end-stage renal disease, but it's less common than neuropathy [2]. *Cardiovascular Disease* - **Cardiovascular disease (CVD)**, including coronary artery disease, stroke, and peripheral artery disease, is a major cause of morbidity and mortality in diabetic patients [2]. - While highly significant, it is a macrovascular complication and its overall prevalence as a specific "complication" is not considered higher than peripheral neuropathy in terms of initial onset and detection.

Q: Which of the following is the most useful investigation for thyroid function?

TSH. TSH - **Thyroid-Stimulating Hormone (TSH)** is the most sensitive and specific test for assessing thyroid function as it reflects the feedback loop between the pituitary gland and the thyroid [1]. - An abnormal TSH level usually indicates either **hypothyroidism** (high TSH) or **hyperthyroidism** (low TSH), even before changes in T3 or T4 are apparent [1]. *T3* - **Triiodothyronine (T3)** is primarily used to confirm a diagnosis of hyperthyroidism, especially when T4 levels are normal but TSH is suppressed [1]. - It is less reliable for initial screening due to its **short half-life** and significant diurnal variation. [1] *T4* - **Thyroxine (T4)** is a good indicator of thyroid hormone production, but its levels can be affected by **protein binding** and non-thyroidal illnesses. - While total T4 is often included in a thyroid panel, **free T4** is more accurate as it reflects the metabolically active hormone not bound to proteins [1]. *Thyroglobulin* - **Thyroglobulin** is primarily used as a tumor marker for monitoring recurrence in patients with differentiated thyroid cancer after thyroidectomy [1]. - It plays no significant role in the initial **assessment of general thyroid function** or diagnosis of hyper/hypothyroidism [1].

Q: A 45-year-old woman complains of tingling in her hands and feet, 24 hours after removal of follicular thyroid carcinoma. Her symptoms rapidly progress to severe muscle cramps, laryngeal stridor, and convulsions. Which of the following laboratory findings would be expected in this patient prior to treatment?

Decreased serum calcium and decreased PTH. ***Decreased serum calcium and decreased PTH*** - The symptoms of **tingling**, **muscle cramps**, **laryngeal stridor**, and **convulsions** are classic signs of **hypocalcemia**. [1] - Following thyroidectomy, **parathyroid glands** can be inadvertently removed or damaged, leading to **hypoparathyroidism**, which results in decreased parathyroid hormone (PTH) levels and subsequent hypocalcemia. [1] *Decreased serum calcium and increased PTH* - This pattern is characteristic of **secondary hyperparathyroidism**, where low calcium levels stimulate increased PTH production. [1] - However, in this case, the hypocalcemia is a direct result of parathyroid damage during surgery, leading to *decreased* PTH. *Increased serum calcium and decreased PTH* - This pattern is characteristic of **primary hyperparathyroidism**, where an adenoma or hyperplasia of the parathyroid glands causes excessive PTH production, leading to hypercalcemia. [1] - This patient is experiencing symptoms consistent with hypocalcemia, not hypercalcemia. *Increased serum calcium and increased PTH* - This combination is rare and could suggest conditions like **familial hypocalciuric hypercalcemia**, where inappropriately high PTH is seen despite elevated calcium. [1] - However, the patient's symptoms are of hypocalcemia, and the history points towards iatrogenic hypoparathyroidism.

Q: An obese patient presented in casualty in an unconscious state, with a blood glucose level of 400 mg/dL and urine testing positive for sugar and ketones. Which drug is most useful in his management?

Insulin. Insulin - The patient presents with **hyperglycemia**, **ketonuria**, and an **unconscious state**, suggestive of **diabetic ketoacidosis (DKA)** or at least severe uncontrolled diabetes requiring urgent glucose management [1], [4]. - **Insulin therapy** is crucial for DKA management, as it lowers blood glucose, resolves ketosis, and helps correct electrolyte imbalances [3]. *Glibenclamide* - This is a **sulfonylurea** that stimulates insulin release from pancreatic beta cells. - It is **contraindicated in DKA** because the pancreas is often severely stressed or non-functional, and it can worsen hypoglycemia if given inappropriately [2]. *Troglitazone* - This is a **thiazolidinedione** (glitazone) which improves insulin sensitivity in peripheral tissues. - It is **not used for acute hyperglycemia or DKA** and was withdrawn from the market due to liver toxicity. *Chlorpropamide* - This is an older **first-generation sulfonylurea**, similar to glibenclamide, that stimulates insulin secretion. - It has a **long half-life** and a higher risk of **hypoglycemia**, making it unsuitable for acute, severe hyperglycemia like DKA [2].

Q: All of the following are features of Graves' disease except:

More common in males. ***More common in males*** - **Graves' disease** is significantly **more common in females** than males, with a female-to-male ratio of approximately 5-10:1. [2] [3] - This option presents a characteristic that is **not a feature** of Graves' disease, as the prevalence is much higher in women. *Tremor* - **Tremor** is a common symptom of **hyperthyroidism**, often described as a fine, rapid tremor, especially in the hands. [3] - It is caused by the **increased adrenergic stimulation** and metabolic rate associated with excess thyroid hormones. *Pretibial myxoedema* - **Pretibial myxoedema** (also known as Graves' dermopathy) is a specific dermatological manifestation of **Graves' disease**. [1] [2] - It involves **localized thickening and discoloration** of the skin, typically on the shins, due to the accumulation of glycosaminoglycans. *Intolerance to heat* - **Heat intolerance** is a classic symptom of **hyperthyroidism** and is a common finding in patients with Graves' disease. [3] - This occurs due to the **increased basal metabolic rate** and excessive heat production stimulated by high levels of thyroid hormones.

Q: A 28-year-old man presents to the emergency department with a severe headache, palpitations, excessive sweating, chest pain, visual disturbances, dyspnea, paresthesias, constipation, and a sense of impending doom, which occur primarily at night, over a period of two weeks. His blood pressure is 130/80 mmHg while supine and 90/60 mmHg while standing, and his blood sugar is 240 mg/dL. Which of the following is the most likely diagnosis?

Pheochromocytoma. **Pheochromocytoma** - This patient presents with a classic triad of symptoms: **headaches**, **sweating**, and **palpitations**, often referred to as the "PHE" symptoms, which are highly suggestive of **pheochromocytoma**. - Additional findings such as **orthostatic hypotension**, **hyperglycemia**, and nocturnal episodes further support the diagnosis of a **catecholamine-secreting tumor**. *Familial dysautonomia syndrome* - This is a rare genetic disorder affecting the **autonomic nervous system**, primarily seen in individuals of Ashkenazi Jewish descent, and typically presents in infancy or early childhood. - While it involves autonomic dysfunction, it is not characterized by paroxysmal episodes of severe hypertension and acute symptoms like those described, nor by a new onset of these symptoms in a 28-year-old. *Opiate withdrawal syndrome* - Symptoms of opiate withdrawal include **muscle aches**, **nausea**, **vomiting**, **diarrhea**, **dilated pupils**, and **piloerection**, often accompanied by psychological distress. - The presented symptoms, particularly the severe headache, chest pain, visual disturbances, and significant hyperglycemia, are not typical features of opiate withdrawal. *Alcohol withdrawal syndrome* - This syndrome can cause **tremors**, **autonomic hyperactivity** (e.g., sweating, elevated heart rate, hypertension), **anxiety**, and in severe cases, **seizures** or **delirium tremens**. - While some autonomic symptoms overlap, the highly specific triad of severe headache, palpitations, and profuse sweating, along with significant hyperglycemia and orthostatic hypotension, points away from alcohol withdrawal as the primary diagnosis.

Q: In a comatose patient with a blood glucose level of 750 mg/dL, which test is most important to perform in addition to serum potassium?

Arterial blood gases. ***Arterial blood gases*** - In a comatose patient with severe hyperglycemia (750 mg/dL), **arterial blood gases (ABGs)** are crucial to assess for **acidosis**, which could indicate **diabetic ketoacidosis (DKA)** or **hyperosmolar hyperglycemic state (HHS)** with lactic acidosis [1], [4]. - The **pH**, **bicarbonate (HCO3-)**, and **pCO2** levels from ABGs help determine the severity and type of metabolic derangement, guiding immediate treatment, especially for potential **cerebral edema** [3], [4]. *Serum creatinine* - While important for assessing **kidney function** in hyperosmolar states, it does not directly evaluate the immediate acid-base status that is critical for neurologic function in a comatose patient. - Renal insufficiency can exacerbate electrolyte imbalances and fluid overload but is secondary to the immediate need for acid-base assessment. *Serum sodium* - **Serum sodium** is important for calculating **effective serum osmolality**, which is elevated in both DKA and HHS, contributing to mental status changes [2]. - However, while important, it does not provide information about the **acid-base balance**, which is a more critical determinant of immediate neurologic stability and treatment in deep coma. *Serum ketones* - **Serum ketones** are essential for distinguishing between **DKA** (high ketones) and **HHS** (low or absent ketones) [4]. - While vital for diagnosis, ketones alone do not give the full picture of **acid-base status** (pH, bicarbonate) which is directly assessed by ABGs and more immediately actionable in managing a severely ill, comatose patient [1].

Q: Which of the following is seen in Conn's syndrome?

Hypokalemia. ***Hypokalemia*** - In Conn's syndrome (primary hyperaldosteronism), excessive **aldosterone** secretion leads to increased renal reabsorption of sodium and excretion of **potassium** and hydrogen ions, resulting in hypokalemia. - This persistent electrolyte imbalance can manifest clinically as muscle weakness, fatigue, and cardiac arrhythmias. *Hypertension* - While hypertension is a prominent feature of Conn's syndrome due to increased sodium reabsorption and water retention, it is a **symptom** or **consequence** of the condition, not the underlying biochemical derangement that defines the syndrome itself. - The elevated aldosterone causes volume expansion and increased vascular tone, leading to systemic hypertension. *Metabolic alkalosis* - Metabolic alkalosis can occur in Conn's syndrome due to the renal excretion of **hydrogen ions** in exchange for sodium reabsorption. - However, it is a **secondary effect** of the hyperaldosteronism and is not the primary defining biochemical abnormality like hypokalemia. *Edema* - Edema is generally **not a common or prominent** feature of Conn's syndrome despite the increased sodium reabsorption. - The body's "escape phenomenon" often limits significant fluid retention and overt edema, preventing gross fluid overload.

Question 1

Which one of the following is the earliest manifestation of Cushing's syndrome?

Accepted Answer

Loss of diurnal variation

Answer

Increased ACTH

Answer

Increased plasma cortisol

Answer

Increased urinary metabolites of cortisol

Question 2

Which of the following statements about pheochromocytoma is true?

Accepted Answer

Arises from chromaffin cells of adrenal medulla

Answer

Bilateral in 20% of all cases

Answer

Hypotension rules out pheochromocytoma

Answer

Almost always a malignant tumor

Question 3

Which one of the following is the MOST common complication of diabetes mellitus?

Accepted Answer

Peripheral Neuropathy

Answer

Diabetic Retinopathy

Answer

Diabetic Nephropathy

Answer

Cardiovascular Disease

Question 4

Which of the following is the most useful investigation for thyroid function?

Accepted Answer

TSH

Answer

T3

Answer

T4

Answer

Thyroglobulin

Question 5

A 45-year-old woman complains of tingling in her hands and feet, 24 hours after removal of follicular thyroid carcinoma. Her symptoms rapidly progress to severe muscle cramps, laryngeal stridor, and convulsions. Which of the following laboratory findings would be expected in this patient prior to treatment?

Accepted Answer

Decreased serum calcium and decreased PTH

Answer

Decreased serum calcium and increased PTH

Answer

Increased serum calcium and decreased PTH

Answer

Increased serum calcium and increased PTH

Question 6

An obese patient presented in casualty in an unconscious state, with a blood glucose level of 400 mg/dL and urine testing positive for sugar and ketones. Which drug is most useful in his management?

Accepted Answer

Insulin

Answer

Glibenclamide

Answer

Troglitazone

Answer

Chlorpropamide

Question 7

All of the following are features of Graves' disease except:

Accepted Answer

More common in males

Answer

Pretibial myxoedema

Answer

Intolerance to heat

Answer

Tremor

Question 8

A 28-year-old man presents to the emergency department with a severe headache, palpitations, excessive sweating, chest pain, visual disturbances, dyspnea, paresthesias, constipation, and a sense of impending doom, which occur primarily at night, over a period of two weeks. His blood pressure is 130/80 mmHg while supine and 90/60 mmHg while standing, and his blood sugar is 240 mg/dL. Which of the following is the most likely diagnosis?

Accepted Answer

Pheochromocytoma

Answer

Familial dysautonomia syndrome

Answer

Opiate withdrawal syndrome

Answer

Alcohol withdrawal syndrome

Question 9

In a comatose patient with a blood glucose level of 750 mg/dL, which test is most important to perform in addition to serum potassium?

Accepted Answer

Arterial blood gases

Answer

Serum creatinine

Answer

Serum sodium

Answer

Serum ketones

Question 10

Which of the following is seen in Conn's syndrome?

Accepted Answer

Hypokalemia

Answer

Metabolic alkalosis

Answer

Hypertension

Answer

Edema

Endocrinology — MCQs

Endocrinology — MCQs

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