Endocrinology Practice Questions

Q: 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?

Nephrogenic diabetes insipidus due to hypercalcemia. ***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.

Q: 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.

Diastolic hypertension. ***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].

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

Insulin is never used in Type II Diabetes mellitus. ***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]

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

Primary hyperparathyroidism. ***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].

Q: All are true regarding Klinefelter's syndrome except for which of the following?

Webbing of neck. ***Webbing of neck*** - **Webbing of the neck** is associated with Turner syndrome [2], not Klinefelter's syndrome, making it an incorrect statement regarding the latter [4]. - Klinefelter's syndrome typically does **not** feature neck webbing as a clinical sign. *Gynecomastia* - Gynecomastia is a common feature in Klinefelter's syndrome due to **hormonal imbalances**, leading to breast tissue development [1]. - It is seen in many affected individuals and is therefore an accurate statement regarding the syndrome. *Increased FSH levels* - Patients with Klinefelter's syndrome often exhibit **elevated FSH levels** due to primary testicular failure [1]. - This happens because the Sertoli cells are unable to support spermatogenesis, resulting in increased FSH as a compensatory mechanism [3]. *Small Testes* - Small testes (hypogonadism) are a hallmark of Klinefelter's syndrome due to the disruption of normal testicular function [1]. - This condition results in underdeveloped testicular tissue owing to the extra X chromosome [1].

Q: Which condition is primarily associated with tetany?

Hypocalcemia. ***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.

Q: Among the following, which is a feature of testicular feminization syndrome?

High testosterone levels. High testosterone levels - Individuals with testicular feminization syndrome (also known as androgen insensitivity syndrome) have testes that produce normal to high levels of testosterone. [1] - However, due to a lack of functional androgen receptors, the body cannot respond to this testosterone, leading to feminization. [1] XX pattern - Testicular feminization syndrome is characterized by a 46,XY karyotype, meaning individuals have male chromosomes. - The XX pattern refers to female chromosomal makeup, which is not present in this syndrome. Commonly reared as male - Due to their female external phenotype and development, individuals with testicular feminization syndrome are almost invariably reared as females. - Their condition is often diagnosed when they present with primary amenorrhea or lack of pubertal feminization. Well formed female internal genitalia - Individuals with this syndrome have undescended testes but lack a uterus and fallopian tubes because the testes produce Müllerian Inhibiting Substance (MIS), which causes regression of Müllerian structures. - They typically have a shortened or blind-ended vagina but no other internal female reproductive organs.

Q: Which of the following is the initial investigation of choice for a patient presenting with a solitary nodule of the thyroid?

FNAC. ***FNAC*** - **Fine needle aspiration cytology (FNAC)** is the most important initial investigation for a solitary thyroid nodule to determine if it is benign or malignant. [1] - It offers a highly accurate and minimally invasive method for **cytological analysis** to guide further management. *Thyroid function test* - While important for assessing **thyroid hormone levels** and diagnosing hyper or hypothyroidism, it does not directly evaluate the **malignant potential** of a nodule. [1] - Normal thyroid function does **not rule out malignancy** within a nodule. *Radionuclide scan* - A **radionuclide scan** is useful for assessing the **functional status** of a nodule (hot or cold). [1] - However, non-functional (**cold**) nodules are more suspicious for malignancy, but the scan doesn't provide **histological diagnosis**. *MRI* - **MRI** provides detailed anatomical imaging of the thyroid and surrounding structures but is generally not the **initial diagnostic test of choice** for evaluating a solitary nodule. [1] - It is typically reserved for assessing **nodule extension** or **lymph node involvement** once malignancy is suspected or confirmed. [1]

Q: What is the most common cause of hypothyroidism in pregnancy?

Autoimmune thyroiditis. ***Autoimmune thyroiditis*** - **Hashimoto's thyroiditis** is the most common autoimmune cause of hypothyroidism, and it is also the leading cause of hypothyroidism in pregnant women. - This condition involves the immune system attacking the thyroid gland, leading to reduced production of **thyroid hormones**. *Nutritional* - **Iodine deficiency** is a nutritional cause of hypothyroidism, but it is less common in areas with adequate iodine intake and fortification programs. - While iodine is crucial for thyroid hormone synthesis, **autoimmune destruction** of the thyroid gland is generally a more prevalent cause of deficiency in pregnant women in developed countries. *Irradiation* - Hypothyroidism due to **radiation exposure** to the neck is a potential cause, but it is typically linked to prior therapeutic interventions for cancers. - This is not a common cause of hypothyroidism in the general pregnant population unless there's a history of such treatment. *Anti thyroid drugs ie iatrogenic* - **Antithyroid drugs** are used to treat hyperthyroidism and can indeed cause iatrogenic (treatment-induced) hypothyroidism. - However, this would only be relevant in pregnant women who were being treated for hyperthyroidism, and it is not the most common underlying cause of a de novo presentation of hypothyroidism during pregnancy.

Question 1

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?

Accepted Answer

Nephrogenic diabetes insipidus due to hypercalcemia

Answer

Renal tubular acidosis due to hypercalcemia

Answer

Chronic renal failure secondary to hypercalcemia

Answer

Increased renal excretion of water due to PTH action

Question 2

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.

Accepted Answer

Diastolic hypertension

Answer

Low renin secretion

Answer

High aldosterone secretion

Answer

Metabolic alkalosis

Question 3

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

Accepted Answer

Insulin is never used in Type II Diabetes mellitus

Answer

Insulin levels may be decreased in patients with Type II Diabetes mellitus

Answer

Insulin is essential to reverse Diabetic Ketoacidosis

Answer

Intravenous Insulin is administered as a sliding scale in the hospital setting

Question 4

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

Accepted Answer

Primary hyperparathyroidism

Answer

Polycystic kidney disease

Answer

Renal tubular acidosis (RTA)

Answer

Paget's disease of bone (osteitis deformans)

Question 5

All are true regarding Klinefelter's syndrome except for which of the following?

Accepted Answer

Webbing of neck

Answer

Gynecomastia

Answer

Increased FSH levels

Answer

Small Testes

Question 6

Which condition is primarily associated with tetany?

Accepted Answer

Hypocalcemia

Answer

None of the options

Answer

Hyperparathyroidism

Answer

Hypercalcemia

Question 7

Among the following, which is a feature of testicular feminization syndrome?

Accepted Answer

High testosterone levels

Answer

XX pattern

Answer

Commonly reared as male

Answer

Well formed female internal genitalia

Question 8

Which of the following statements is true regarding primary hyperparathyroidism?

Accepted Answer

Adenoma is the most common cause of primary hyperparathyroidism.

Answer

Elevated serum calcium is a key diagnostic criterion.

Answer

Surgery is indicated for symptomatic patients or those with significant biochemical abnormalities.

Answer

Parathyroid carcinoma is the most common cause of primary hyperparathyroidism.

Question 9

Which of the following is the initial investigation of choice for a patient presenting with a solitary nodule of the thyroid?

Accepted Answer

FNAC

Answer

Thyroid function test

Answer

Radionuclide scan

Answer

MRI

Question 10

What is the most common cause of hypothyroidism in pregnancy?

Accepted Answer

Autoimmune thyroiditis

Answer

Nutritional

Answer

Irradiation

Answer

Anti thyroid drugs ie iatrogenic

Endocrinology — MCQs

Endocrinology — MCQs

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