Endocrinology Practice Questions

Q: Which of the following tests is used to distinguish primary hyperparathyroidism from familial benign hypercalcemia?

Urinary calcium levels. **Explanation:** The clinical distinction between **Primary Hyperparathyroidism (PHPT)** and **Familial Hypocalciuric Hypercalcemia (FHH)**—also known as familial benign hypercalcemia—is critical because PHPT requires surgery, while FHH is a benign condition where surgery is ineffective. **Why Urinary Calcium is the Correct Answer:** The underlying pathophysiology of FHH involves an inactivating mutation in the **Calcium-Sensing Receptor (CaSR)**. This leads to a higher "set-point" for calcium, causing the kidneys to reabsorb calcium excessively despite high serum levels. * **FHH:** Characterized by **low urinary calcium excretion** (Hypocalciuria). The Calcium-to-Creatinine Clearance Ratio (**CCCR**) is typically ** 0.02**. **Analysis of Incorrect Options:** * **A. Serum PTH levels:** Both conditions present with elevated or inappropriately normal PTH levels, making this test non-discriminatory. * **B. Serum calcium levels:** Both conditions present with hypercalcemia. * **D. Serum phosphorus levels:** Both conditions can present with low or low-normal serum phosphorus due to the phosphaturic effects of PTH. **NEET-PG High-Yield Pearls:** * **CCCR Formula:** (Urinary Ca × Serum Cr) / (Serum Ca × Urinary Cr). * **FHH Inheritance:** Autosomal Dominant. * **Clinical Clue:** If a patient has asymptomatic hypercalcemia, a family history of "failed" parathyroid surgeries, and low urinary calcium, suspect FHH. * **Management:** PHPT often requires parathyroidectomy; FHH requires no treatment (it is "benign").

Q: A 20-year-old male is admitted to the ICU for diabetic ketoacidosis (DKA). His mother reports increased thirst and frequent urination recently. He has no prior diabetes diagnosis and no family history of diabetes. His BMI is 42 kg/m2. Anti-GAD antibodies and anti-islet cell antibodies (ICA) are not detected. Which of the following statements is true regarding this patient?

The patient has type 2 diabetes mellitus.. ### Explanation The correct answer is **D. The patient has type 2 diabetes mellitus.** This patient presents with **Ketosis-Prone Type 2 Diabetes (KPD)**, also known as "Flatbush Diabetes." While DKA is classically associated with Type 1 Diabetes (T1DM), it is increasingly seen in patients with Type 2 Diabetes (T2DM), particularly those with obesity [1]. **Why Option D is correct:** The diagnosis of T2DM is supported by the patient’s **high BMI (42 kg/m²)** and the **absence of pancreatic autoantibodies** (Anti-GAD and ICA). In KPD, patients present with acute insulin deficiency (leading to DKA), often triggered by glucose toxicity which suppresses beta-cell function [1]. With treatment, they later regain significant beta-cell function and can often be managed with oral hypoglycemic agents rather than lifelong insulin [1]. **Why other options are incorrect:** * **Option A & B:** While young age and DKA are "textbook" features of T1DM [2], the presence of morbid obesity and negative autoantibodies strongly point toward T2DM. DKA is no longer considered pathognomonic for T1DM [1]. * **Option C:** Maturity-Onset Diabetes of the Young (MODY) typically presents in non-obese individuals with a strong autosomal dominant family history [3]. This patient has no family history and a high BMI, making MODY unlikely. ### Clinical Pearls for NEET-PG: * **Antibody Testing:** Negative Anti-GAD, ICA, and IA-2 antibodies in a patient with DKA should raise suspicion for Ketosis-Prone T2DM. * **AB Classification:** KPD is often classified using the "Aβ" system (A: Autoantibodies; β: Beta-cell function). This patient fits the **A-β+** category (Antibody negative, preserved beta-cell function). * **Management:** After resolving the initial DKA with insulin, these patients should be re-evaluated for transition to oral drugs (like Metformin) once glucose toxicity resolves [1].

Q: Malignancy associated hypercalcemia is most commonly due to which of the following mechanisms?

Parathyroid hormone-related peptide production. **Explanation:** Hypercalcemia of malignancy (HCM) is the most common cause of hypercalcemia in hospitalized patients. It occurs via four distinct mechanisms, but the most frequent is **Humoral Hypercalcemia of Malignancy (HHM)**. **Why Option B is Correct:** Approximately **80% of cases** of HCM are caused by the secretion of **Parathyroid Hormone-related Peptide (PTHrP)** by tumor cells [2]. PTHrP mimics the action of PTH by binding to the PTH-1 receptor in bones (increasing osteoclast activity) and kidneys (increasing calcium reabsorption) [1]. It is most commonly associated with **Squamous cell carcinomas** (lung, head, and neck), renal, and breast cancers [3]. Unlike true hyperparathyroidism, PTH levels in these patients are suppressed [3]. **Why Other Options are Incorrect:** * **Option A (Tumor Lysis Syndrome):** This typically causes **hypocalcemia** (due to phosphate release binding with calcium) and hyperuricemia, not hypercalcemia. * **Option C (IL-7):** While cytokines like IL-1, IL-6, and TNF-alpha (Osteoclast Activating Factors) contribute to local osteolytic hypercalcemia (common in Multiple Myeloma), IL-7 is not a primary mediator of malignancy-associated hypercalcemia. * **Option D (IGF-BP):** These proteins regulate growth factor activity but do not play a direct role in calcium homeostasis or the pathogenesis of HCM. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most common mechanism:** PTHrP production (80%). 2. **Second most common mechanism:** Local osteolytic hypercalcemia (20%), seen in Multiple Myeloma and breast cancer bone metastases. 3. **Rare mechanism:** 1,25-dihydroxyvitamin D production (seen in Lymphomas) [3]. 4. **Laboratory findings in HHM:** High Calcium, Low PTH, Low 1,25-(OH)₂D (usually), and High PTHrP. 5. **Treatment of choice:** Aggressive IV hydration (Normal Saline) followed by IV Bisphosphonates (e.g., Zoledronic acid).

Q: A 30-year-old female presents with a need to progressively buy larger and wider shoes and cannot wear any of her rings because they are too small. A physical examination shows a prominent brow, protruding lower jaw, and spaces between all of her teeth. This woman may have a tumor in which one of the following organs or tissues?

Hypothalamus. ### Explanation **Correct Option: A (Hypothalamus)** The clinical presentation describes classic **Acromegaly**, characterized by acral enlargement (increased shoe/ring size), frontal bossing (prominent brow), macrognathia (protruding jaw), and teeth spacing (diastema). While most cases of acromegaly are caused by a Growth Hormone (GH)-secreting pituitary adenoma [1], the question asks for the source of a tumor that could cause this syndrome. In rare instances, **ectopic secretion of Growth Hormone-Releasing Hormone (GHRH)** can lead to somatotroph hyperplasia and secondary acromegaly [3]. The **hypothalamus** is a primary site for GHRH production [2]. A hypothalamic gangliocytoma or hamartoma secreting GHRH can result in the clinical features described. **Analysis of Incorrect Options:** * **B. Bone marrow:** Bone marrow disorders (like multiple myeloma or leukemias) do not cause soft tissue or bony overgrowth characteristic of GH excess. * **C. Adrenal glands:** Adrenal tumors typically present with Cushing’s syndrome (cortisol), Conn’s syndrome (aldosterone), or virilization (androgens), none of which cause acral enlargement [4]. * **D. Pancreas:** While pancreatic neuroendocrine tumors (NETs) can rarely secrete ectopic GHRH or GH, the hypothalamus is a more direct physiological source of GHRH in the context of neuroendocrine regulation. **NEET-PG High-Yield Pearls:** * **Best Initial Test:** Serum IGF-1 levels (more stable than GH) [1]. * **Gold Standard/Confirmatory Test:** Oral Glucose Tolerance Test (OGTT) with GH measurement; failure to suppress GH <1 ng/mL is diagnostic [1]. * **Most Common Cause:** Pituitary Adenoma (Somatotroph adenoma) [3]. * **Ectopic GHRH Sources:** Hypothalamic tumors, Bronchial carcinoid, and Pancreatic NETs. * **Associated Conditions:** Often associated with MEN-1 syndrome (Pituitary, Parathyroid, Pancreas).

Q: Which of the following is not seen in Secondary Adrenal insufficiency?

Hyperpigmentation. In **Secondary Adrenal Insufficiency (SAI)**, the pathology lies in the pituitary gland (decreased ACTH) or hypothalamus (decreased CRH), rather than the adrenal cortex itself [2]. ### Why Hyperpigmentation is NOT seen: Hyperpigmentation is a hallmark of **Primary Adrenal Insufficiency (Addison’s Disease)** [1]. In Primary AI, the lack of cortisol feedback causes a massive compensatory increase in **ACTH** and its precursor, **Pro-opiomelanocortin (POMC)**. POMC is cleaved into ACTH and **Melanocyte-Stimulating Hormone (MSH)**; high levels of these hormones stimulate melanocytes, leading to skin and mucosal darkening. In SAI, ACTH levels are low or inappropriately normal, so hyperpigmentation does not occur. ### Analysis of Incorrect Options: * **Postural Hypotension:** While more severe in Primary AI (due to mineralocorticoid deficiency), it can still occur in SAI due to decreased vascular tone and reduced cardiac output resulting from cortisol deficiency. * **Hypoglycemia:** Cortisol is a counter-regulatory hormone that promotes gluconeogenesis. Its absence in SAI leads to impaired glucose production, especially during fasting or stress. * **Lassitude:** General fatigue, weakness, and lethargy are universal symptoms of glucocorticoid deficiency regardless of the site of the lesion [4]. ### NEET-PG High-Yield Pearls: 1. **Mineralocorticoids:** In SAI, the Renin-Angiotensin-Aldosterone System (RAAS) remains intact. Therefore, **hyperkalemia is absent** in SAI (a common "except" question) [2]. 2. **Aldosterone:** Is preserved in SAI but lost in Primary AI. 3. **Most Common Cause:** The most common cause of SAI is the **abrupt withdrawal of long-term exogenous steroid therapy**. 4. **Cosyntropin Test:** Used to differentiate; in SAI, the adrenals may be "atrophied" and fail to respond to an acute ACTH bolus [3].

Q: Thyroid function tests performed on serum from a 33-year-old woman reveal increased TSH, decreased total T4, decreased free T4, and decreased T3 uptake. Which of the following clinical features would be most likely to be seen in this patient?

Weight gain. ### Explanation **Analysis of Thyroid Function Tests (TFTs):** The patient’s lab results—**increased TSH** and **decreased free T4**—are diagnostic of **Primary Hypothyroidism** [1]. The decreased T3 uptake further confirms a low thyroid hormone state (as there are more vacant binding sites on Thyroid Binding Globulin). In hypothyroidism, the basal metabolic rate (BMR) decreases significantly, leading to the clinical manifestations described. **Why Weight Gain is Correct:** In primary hypothyroidism, the deficiency of thyroid hormones leads to a generalized slowing of metabolic processes. **Weight gain** occurs due to a combination of a decreased metabolic rate and the accumulation of glycosaminoglycans (myxedema), which causes fluid retention. This is a classic "hypometabolic" symptom. **Why Other Options are Incorrect:** * **A. Diarrhea:** Hypothyroidism causes decreased gastrointestinal motility, leading to **constipation**. Diarrhea is a feature of hyperthyroidism. * **B. Heat intolerance:** Patients with hypothyroidism feel cold due to low thermogenesis (**cold intolerance**). Heat intolerance is seen in hyperthyroidism [2]. * **C. Hyperactivity:** Hypothyroidism is characterized by psychomotor retardation, fatigue, and lethargy. Hyperactivity and tremors are hallmarks of thyrotoxicosis [2]. **NEET-PG High-Yield Pearls:** * **Most common cause:** Worldwide, iodine deficiency is the leading cause; however, in iodine-sufficient areas (and frequently in exams), **Hashimoto’s Thyroiditis** (autoimmune) is the most common cause. * **Early Sign:** An elevated TSH is the most sensitive initial marker for primary hypothyroidism [1]. * **Wolff-Chaikoff Effect:** Transient hypothyroidism caused by the ingestion of a large amount of iodine (e.g., amiodarone or contrast dye). * **Clinical Sign:** Delayed relaxation of deep tendon reflexes (Hungry-bomb sign) is a highly specific physical finding.

Question 1

Which of the following tests is used to distinguish primary hyperparathyroidism from familial benign hypercalcemia?

Accepted Answer

Urinary calcium levels

Answer

Serum PTH levels

Answer

Serum calcium levels

Answer

Serum phosphorus levels

Question 2

A 20-year-old male is admitted to the ICU for diabetic ketoacidosis (DKA). His mother reports increased thirst and frequent urination recently. He has no prior diabetes diagnosis and no family history of diabetes. His BMI is 42 kg/m2. Anti-GAD antibodies and anti-islet cell antibodies (ICA) are not detected. Which of the following statements is true regarding this patient?

Accepted Answer

The patient has type 2 diabetes mellitus.

Answer

Due to the young age of onset, type 1 diabetes is suspected.

Answer

Because of the presentation with diabetic ketoacidosis, type 1 diabetes is suspected.

Answer

The patient has maturity-onset diabetes of the young.

Question 3

Malignancy associated hypercalcemia is most commonly due to which of the following mechanisms?

Accepted Answer

Parathyroid hormone-related peptide production

Answer

Tumor lysis syndrome

Answer

Interleukin-7 (IL-7) production

Answer

Insulin-like growth factor binding protein (IGF-BP) production

Question 4

A 30-year-old female presents with a need to progressively buy larger and wider shoes and cannot wear any of her rings because they are too small. A physical examination shows a prominent brow, protruding lower jaw, and spaces between all of her teeth. This woman may have a tumor in which one of the following organs or tissues?

Accepted Answer

Hypothalamus

Answer

Bone marrow

Answer

Adrenal glands

Answer

Pancreas

Question 5

All of the following are associated with Primary aldosteronism EXCEPT?

Accepted Answer

Postural hypotension

Answer

Hypokalaemia

Answer

Hypernatremia

Answer

Metabolic alkalosis

Question 6

What is the most common cause of hyperparathyroidism?

Accepted Answer

Post-thyroid surgery

Answer

Di George syndrome

Answer

McCune-Albright syndrome

Answer

Parathyroid hypoplasia

Question 7

A 50-year-old obese female presents with recurrent candidal urinary infections and excessive thirst. She also reports frequent nighttime urination. What is the initial diagnostic test you would prefer for this patient?

Accepted Answer

Random plasma glucose level

Answer

HbA1c

Answer

Oral glucose tolerance test

Answer

Plasma C-peptide level

Question 8

A patient presents with a large, protruding jaw; large hands and feet; normal height; and an elevated blood glucose level. What is the most likely diagnosis?

Accepted Answer

Acromegaly due to a growth hormone-producing tumor that developed in adulthood.

Answer

Elevated blood levels of aldosterone and renin resulting from an atherosclerotic plaque in a renal artery.

Answer

Hyperprolactinemia due to a pituitary tumor.

Answer

Cushing syndrome due to an adrenal tumor.

Question 9

Which of the following is not seen in Secondary Adrenal insufficiency?

Accepted Answer

Hyperpigmentation

Answer

Postural hypotension

Answer

Hypoglycemia

Answer

Lassitude

Question 10

Thyroid function tests performed on serum from a 33-year-old woman reveal increased TSH, decreased total T4, decreased free T4, and decreased T3 uptake. Which of the following clinical features would be most likely to be seen in this patient?

Accepted Answer

Weight gain

Answer

Diarrhea

Answer

Heat intolerance

Answer

Hyperactivity

Endocrinology — MCQs

Endocrinology — MCQs

On this page

Practice by Chapter

Want unlimited practice?