Endocrinology — MCQs
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Which of the following statements regarding obesity syndromes are true or false?
A 40-year-old man presents with nausea, vomiting, diarrhea, and cramping abdominal pain. His temperature is 38°C, blood pressure is 90/60 mm Hg, and pulse rate is 90/minute. Physical examination reveals dehydration with sunken eyeballs, dry tongue, and poor skin turgor. Hyperpigmentation is noted in the palmar creases and the gingival margins. Laboratory results include fasting serum glucose of 62 mg/dL, BUN of 27 mg/dL, Na of 122 mEq/L, and K of 6.5 mEq/L. What is the most likely cause of this patient's symptoms?
A 59-year-old man with type 2 diabetes presents for a screening eye examination. The ophthalmologist reports the development of non-proliferative retinopathy. For this patient with a complication of diabetes, select the most likely findings.
A 20-year-old girl presents with a 9-month history of neck swelling and thyrotoxicosis symptoms. Investigations revealed increased T4 and decreased TSH with a palpable 2 cm nodule. What is the next investigation?
Which of the following statements about Cushing's disease is true?
A patient presents with bilateral proptosis, heat intolerance, and palpitations. Which of the following is the most unlikely diagnosis?
Which of the following symptoms is NOT typically seen in hyponatremia?
Which drug is used in the management of severe hypercalcemia?
Syndrome X is not found in which of the following?
A 55-year-old woman with a history of severe depression and radical mastectomy for breast carcinoma one year ago presents with polyuria, nocturia, and excessive thirst. Laboratory values are as follows: Serum sodium 149 mEq/L, Serum potassium 3.6 mEq/L, Serum calcium 9.5 mg/dL, Glucose 110 mg/dL, BUN 30 mg/dL, Urine osmolarity 150 mOsm/kg. What is the most likely clinical diagnosis?
Endocrinology Indian Medical PG Practice Questions and MCQs
Question 11: Which of the following statements regarding obesity syndromes are true or false?
- A. Prader-Willi syndrome has normal stature with truncal obesity; Laurence-Moon-Biedl is autosomal with polydactyly; Ahlstrom's syndrome patients have moderate mental retardation; Cohen's syndrome patients have craniofacial anomalies and delayed puberty; Carpenter's syndrome have secondary hypogonadism are all true, except Prader-Willi syndrome and Ahlstrom's syndrome are false. (Correct Answer)
- B. Prader-Willi syndrome has normal stature with truncal obesity; Laurence-Moon-Biedl is autosomal with polydactyly; Ahlstrom's syndrome patients have moderate mental retardation; Cohen's syndrome patients have craniofacial anomalies and delayed puberty; Carpenter's syndrome have secondary hypogonadism are all true, except Laurence-Moon-Biedl is false.
- C. Prader-Willi syndrome has normal stature with truncal obesity; Laurence-Moon-Biedl is autosomal with polydactyly; Ahlstrom's syndrome patients have moderate mental retardation; Cohen's syndrome patients have craniofacial anomalies and delayed puberty; Carpenter's syndrome have secondary hypogonadism are all true, except Prader-Willi syndrome is false.
- D. Prader-Willi syndrome has normal stature with truncal obesity; Laurence-Moon-Biedl is autosomal with polydactyly; Ahlstrom's syndrome patients have moderate mental retardation; Cohen's syndrome patients have craniofacial anomalies and delayed puberty; Carpenter's syndrome have secondary hypogonadism are all true, except Prader-Willi syndrome and Carpenter's syndrome are false.
Explanation: This question tests the ability to differentiate between various genetic syndromes associated with obesity, a high-yield area for NEET-PG. [1] ### **Analysis of the Statements** 1. **Prader-Willi Syndrome (PWS):** Characterized by **short stature** (due to GH deficiency), hypotonia, and hyperphagia. The statement claiming "normal stature" is **False**. [1] 2. **Alström Syndrome:** Features include childhood obesity, type 2 diabetes, and sensory loss (blindness/deafness). Crucially, intelligence is usually **normal**. The statement claiming "moderate mental retardation" is **False**. 3. **Laurence-Moon-Bardet-Biedl Syndrome:** An autosomal recessive condition characterized by obesity, **polydactyly**, retinitis pigmentosa, and hypogonadism. This is **True**. [1] 4. **Cohen’s Syndrome:** Characterized by obesity, **craniofacial dysmorphism** (prominent incisors), and **delayed puberty**. This is **True**. 5. **Carpenter’s Syndrome:** An autosomal recessive acrocephalopolysyndactyly syndrome featuring craniosynostosis, obesity, and **hypogonadism**. This is **True**. ### **Why Option A is Correct** Option A correctly identifies that while the descriptions for Laurence-Moon-Biedl, Cohen’s, and Carpenter’s syndromes are accurate, the descriptions for **Prader-Willi** (should be short stature) and **Alström** (should be normal intelligence) are **False**. ### **Why Other Options are Incorrect** * **Options B & C:** These are incomplete because they fail to recognize that *both* Prader-Willi and Alström statements contain factual errors. * **Option D:** Incorrectly suggests Carpenter’s syndrome description is false; however, hypogonadism is a recognized feature of this syndrome. ### **High-Yield Clinical Pearls for NEET-PG** * **Prader-Willi Syndrome:** Most common genetic cause of obesity; caused by absence of expression of the **paternal** copy of chromosome 15q11-q13. * **Bardet-Biedl vs. Alström:** Both have obesity and retinal degeneration, but **polydactyly** is specific to Bardet-Biedl. * **Alström Syndrome:** Think of it as "Obesity + Sensory loss + Normal IQ."
Question 12: A 40-year-old man presents with nausea, vomiting, diarrhea, and cramping abdominal pain. His temperature is 38°C, blood pressure is 90/60 mm Hg, and pulse rate is 90/minute. Physical examination reveals dehydration with sunken eyeballs, dry tongue, and poor skin turgor. Hyperpigmentation is noted in the palmar creases and the gingival margins. Laboratory results include fasting serum glucose of 62 mg/dL, BUN of 27 mg/dL, Na of 122 mEq/L, and K of 6.5 mEq/L. What is the most likely cause of this patient's symptoms?
- A. Amyloidosis
- B. Autoimmunity (Correct Answer)
- C. Metastatic cancer
- D. Sarcoidosis
Explanation: **Explanation:** The clinical presentation of hypotension, dehydration, hypoglycemia, hyponatremia, and hyperkalemia, combined with hyperpigmentation, is classic for **Primary Adrenal Insufficiency (Addison’s Disease)** [2]. The patient is currently in an **Addisonian Crisis**, likely precipitated by an acute stressor [1]. 1. **Why Autoimmunity is Correct:** In developed countries and increasingly in urban India, **Autoimmune Adrenalitis** (either isolated or as part of Polyglandular Autoimmune Syndromes) is the **most common cause** of primary adrenal insufficiency (responsible for ~80% of cases) [3]. It involves the destruction of the adrenal cortex, leading to a deficiency of cortisol (causing hypoglycemia and hypotension) and aldosterone (causing hyponatremia and hyperkalemia). The hyperpigmentation occurs because low cortisol triggers a compensatory increase in ACTH; the precursor molecule (POMC) also produces Melanocyte-Stimulating Hormone (MSH). 2. **Why Incorrect Options are Wrong:** * **Amyloidosis and Sarcoidosis:** These are infiltrative diseases that can involve the adrenal glands, but they are rare causes of clinical adrenal insufficiency compared to autoimmunity. * **Metastatic Cancer:** While cancers (especially lung and breast) frequently metastasize to the adrenals, they rarely destroy >90% of the gland required to cause symptomatic insufficiency [3]. **NEET-PG High-Yield Pearls:** * **Most common cause worldwide:** Autoimmunity (formerly Tuberculosis). * **Most common cause in developing countries/India:** Tuberculosis (look for adrenal calcification on CT) [3]. * **Electrolyte Hallmark:** Hyponatremia + Hyperkalemia + Metabolic Acidosis (Non-gap). * **Diagnosis:** Best initial test is the **ACTH Stimulation Test** (Cosyntropin test) [1]. * **Management of Crisis:** Immediate IV fluids (Normal Saline) and high-dose **IV Hydrocortisone**. Do not wait for lab confirmation [1].
Question 13: A 59-year-old man with type 2 diabetes presents for a screening eye examination. The ophthalmologist reports the development of non-proliferative retinopathy. For this patient with a complication of diabetes, select the most likely findings.
- A. Microaneurysms and hemorrhage (dot and blot) (Correct Answer)
- B. Vitreous hemorrhage
- C. Dilated veins
- D. Open-angle glaucoma
Explanation: **Explanation:** Diabetic Retinopathy (DR) is a leading cause of blindness and is categorized into Non-Proliferative (NPDR) and Proliferative (PDR) stages. **Why Option A is Correct:** The earliest clinical sign of NPDR is the formation of **microaneurysms**, which appear as small red dots due to capillary wall outpouching [1]. As these capillaries leak or rupture within the deeper layers of the retina (inner nuclear and outer plexiform layers), they create **"dot and blot" hemorrhages**. Other features of NPDR include hard exudates (lipid leaks) and cotton wool spots (nerve fiber layer infarcts). **Analysis of Incorrect Options:** * **B. Vitreous hemorrhage:** This is a hallmark of **Proliferative Diabetic Retinopathy (PDR)** [1]. It occurs when fragile new vessels (neovascularization) bleed into the vitreous cavity [1]. * **C. Dilated veins:** While venous "beading" or loops can occur in severe NPDR, simple dilated veins are more characteristic of Central Retinal Vein Occlusion (CRVO) or early hypertensive changes rather than the primary screening finding for NPDR. * **D. Open-angle glaucoma:** While diabetics have a higher risk of glaucoma, it is a separate pathological entity and not a diagnostic feature of non-proliferative retinopathy. **High-Yield NEET-PG Pearls:** * **Earliest Sign:** Microaneurysms (seen on Fundus Fluorescein Angiography) [1]. * **NPDR vs. PDR:** The defining feature of PDR is **Neovascularization** (NVD/NVE) driven by VEGF [1]. * **Macular Edema:** Can occur at *any* stage of DR and is the most common cause of vision loss in NPDR [1]. * **Screening:** Type 2 DM patients need a fundus exam **at the time of diagnosis**, whereas Type 1 DM patients should be screened **5 years after diagnosis**.
Question 14: A 20-year-old girl presents with a 9-month history of neck swelling and thyrotoxicosis symptoms. Investigations revealed increased T4 and decreased TSH with a palpable 2 cm nodule. What is the next investigation?
- A. Ultrasound (USG) of the thyroid
- B. Thyroid scan (Correct Answer)
- C. Radioactive iodine uptake
- D. CT scan
Explanation: The patient presents with clinical and biochemical evidence of **hyperthyroidism** (↑T4, ↓TSH) associated with a **palpable thyroid nodule**. In the management of a thyroid nodule, the first step is always checking the serum TSH [1]. **1. Why Thyroid Scan is the correct answer:** When TSH is suppressed (low), the priority is to determine if the nodule is "functioning" (autonomously producing hormone) [1]. A **Thyroid Scan (Radionuclide Scanning)** using Technetium-99m or Iodine-123 is the gold standard for this [1][2]. * If the nodule is **"Hot"** (increased uptake), it confirms a Toxic Adenoma. Hot nodules are almost never malignant, so Fine Needle Aspiration (FNA) is not required [1]. * If the nodule is **"Cold"** (no uptake), the risk of malignancy is higher, and the next step would be USG-guided FNA [1]. **2. Why other options are incorrect:** * **A. Ultrasound (USG):** While USG is the first-line imaging for a *euthyroid* nodule, in a *hyperthyroid* patient, the functional status (Scan) takes precedence to avoid unnecessary biopsies of hot nodules [1]. * **C. Radioactive Iodine Uptake (RAIU):** This measures the percentage of iodine trapped by the *entire* gland to differentiate causes of thyrotoxicosis (e.g., Graves' vs. Thyroiditis) [2]. It does not provide the anatomical localization needed to evaluate a specific nodule. * **D. CT Scan:** CT is not used for the initial evaluation of thyroid function or nodules and can interfere with future radioiodine therapy due to iodinated contrast [3]. ### Clinical Pearls for NEET-PG * **Algorithm:** Low TSH → Thyroid Scan; Normal/High TSH → USG followed by FNA (based on TIRADS) [1]. * **Toxic Adenoma (Plummer Disease):** Usually presents as a single "Hot" nodule with suppression of the rest of the gland. * **Rule of Thumb:** "Hot" nodules are safe (benign); "Cold" nodules need biopsy [1].
Question 15: Which of the following statements about Cushing's disease is true?
- A. Serum adrenocorticotropic hormone (ACTH) levels usually are high
- B. A pituitary microadenoma usually is present (Correct Answer)
- C. There is a low incidence of nonendocrine tumors
- D. Suppression of cortisol production by the high-dose dexamethasone suppression test is a characteristic finding
Explanation: ### Explanation **Cushing’s Disease** refers specifically to hypercortisolism caused by an **ACTH-secreting pituitary adenoma**. It is the most common cause of endogenous Cushing’s syndrome (excluding iatrogenic causes). **1. Why the Correct Answer is Right:** In approximately **90% of cases** of Cushing’s disease, the underlying cause is a **pituitary microadenoma** (defined as <10 mm in diameter). These tumors are typically located in the anterior pituitary and are composed of basophilic or chromophobe cells that autonomously secrete ACTH. **2. Analysis of Incorrect Options:** * **Option A:** Serum ACTH levels in Cushing’s disease are typically **normal to modestly elevated**, but not "high" (unlike Ectopic ACTH syndrome, where levels are markedly elevated). The key is that the ACTH is "inappropriately normal" in the presence of high cortisol. * **Option C:** There is actually an **increased incidence** of various tumors in patients with Cushing’s disease, and it can sometimes be part of **MEN 1 syndrome** (Multiple Endocrine Neoplasia type 1), which involves parathyroid and pancreatic tumors. * **Option D:** While Cushing’s disease *does* show suppression with the High-Dose Dexamethasone Suppression Test (HDDST), this is **not a universal characteristic finding** for all cases. Modern guidelines (like the Endocrine Society) prioritize IPSS (Inferior Petrosal Sinus Sampling) over HDDST because the latter has limited sensitivity and specificity in differentiating pituitary from ectopic sources. **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Inferior Petrosal Sinus Sampling (IPSS) is the most reliable method to differentiate Cushing’s disease from Ectopic ACTH syndrome. * **Initial Screening:** 24-hour urinary free cortisol, Low-dose dexamethasone suppression test (LDDST), or late-night salivary cortisol. * **Treatment of Choice:** Transsphenoidal surgery (TSS). * **Nelson’s Syndrome:** Rapid enlargement of a pituitary adenoma following bilateral adrenalectomy due to loss of negative feedback.
Question 16: A patient presents with bilateral proptosis, heat intolerance, and palpitations. Which of the following is the most unlikely diagnosis?
- A. Hashimoto's thyroiditis
- B. Thyroid adenoma
- C. Diffuse thyroid goiter
- D. Riedel's thyroiditis (Correct Answer)
Explanation: The patient presents with a classic triad of **hyperthyroidism** (heat intolerance, palpitations) and **Graves' ophthalmopathy** (bilateral proptosis) [1]. The question asks for the *most unlikely* diagnosis among the options provided. ### **Why Riedel’s Thyroiditis is the Correct Answer** **Riedel’s Thyroiditis** is a rare chronic inflammatory disease characterized by dense fibrous tissue replacing the thyroid parenchyma. Clinically, it presents as a "stony hard," fixed, painless goiter that often causes obstructive symptoms (callout). Crucially, patients are typically **hypothyroid** or euthyroid, and it is **never associated with proptosis**. ### **Analysis of Incorrect Options** * **Hashimoto’s Thyroiditis:** While typically causing hypothyroidism, it can present with a transient hyperthyroid phase known as **"Hashitoxicosis."** Furthermore, Hashimoto’s is associated with the same HLA alleles as Graves' disease; rarely, patients can have co-existing Graves' ophthalmopathy. * **Diffuse Thyroid Goiter:** This is the hallmark of **Graves' Disease**, the most common cause of hyperthyroidism [1]. Graves' is unique because it features extrathyroidal manifestations like bilateral proptosis due to TSH-receptor antibodies affecting orbital fibroblasts [1]. * **Thyroid Adenoma:** A hyperfunctioning (toxic) adenoma causes hyperthyroidism. While it doesn't cause autoimmune proptosis, it is a much more likely cause of the systemic symptoms (palpitations, heat intolerance) than Riedel’s. ### **NEET-PG High-Yield Pearls** * **Riedel’s Thyroiditis:** Associated with **IgG4-related systemic diseases** (e.g., retroperitoneal fibrosis, sclerosing cholangitis). * **Proptosis/Exophthalmos:** Specific to **Graves' Disease** (autoimmune) and not seen in other causes of thyrotoxicosis like Toxic Multinodular Goiter [1]. Treatment for severe inflammatory episodes may involve glucocorticoids or orbital radiotherapy [1]. * **Hard Thyroid Differential:** Riedel’s Thyroiditis vs. Anaplastic Carcinoma. Riedel’s is usually in younger patients and lacks the rapid malignant growth of anaplastic CA.
Question 17: Which of the following symptoms is NOT typically seen in hyponatremia?
- A. Nausea
- B. Delusion (Correct Answer)
- C. Vomiting
- D. Anorexia
Explanation: Hyponatremia (Serum Sodium <135 mEq/L) primarily manifests through gastrointestinal and neurological symptoms due to cerebral edema and increased intracranial pressure [1]. **Explanation of the Correct Answer:** **B. Delusion** is the correct answer because it is a fixed, false belief typically associated with primary psychiatric disorders (like schizophrenia) or chronic organic brain syndromes. While hyponatremia causes significant neurological impairment, it presents as **Delirium** (acute encephalopathy, confusion, or altered sensorium) rather than structured delusions. In severe cases, patients progress from lethargy and disorientation to seizures and coma, but not typically to isolated delusional thinking. **Explanation of Incorrect Options:** * **A & C. Nausea and Vomiting:** These are among the earliest and most common symptoms of hyponatremia [1]. They occur due to cerebral edema affecting the postrema (chemoreceptor trigger zone) and increased intracranial pressure. * **D. Anorexia:** Loss of appetite is a classic non-specific early symptom of electrolyte imbalance, particularly hyponatremia, often preceding more severe neurological decline. **High-Yield Clinical Pearls for NEET-PG:** 1. **Symptom Severity:** Symptoms depend more on the **rate of fall** of sodium rather than the absolute value. 2. **Neurological Spectrum:** Mild (130–135 mEq/L): Asymptomatic; Moderate (125–129 mEq/L): Nausea, headache, confusion; Severe (<125 mEq/L): Vomiting, seizures, somnolence, and coma. 3. **Osmotic Demyelination Syndrome (ODS):** Rapid correction of chronic hyponatremia (>10–12 mEq/L in 24 hours) can lead to Central Pontine Myelinolysis [2]. Remember: *"From Low to High, your Pons will die."* 4. **SIADH:** A common cause of euvolemic hyponatremia; look for low serum osmolality with inappropriately high urine osmolality (>100 mOsm/kg) [1].
Question 18: Which drug is used in the management of severe hypercalcemia?
- A. Furosemide
- B. Prednisolone
- C. Pamidronate
- D. All of the above (Correct Answer)
Explanation: **Explanation:** The management of severe hypercalcemia (typically defined as Serum Calcium >14 mg/dL) requires a multi-pronged approach aimed at increasing urinary excretion, inhibiting bone resorption, and addressing the underlying cause. **Why "All of the above" is correct:** 1. **Pamidronate (Bisphosphonates):** These are the **mainstay of treatment** for severe hypercalcemia, especially when malignancy-associated. They work by inhibiting osteoclast-mediated bone resorption. While they are highly effective, they have a delayed onset of action (24–72 hours). 2. **Furosemide (Loop Diuretics):** Once the patient is adequately rehydrated with IV Normal Saline, loop diuretics are used to promote "calciuresis" (urinary calcium excretion) by inhibiting the Na-K-2Cl symporter in the thick ascending limb of the Loop of Henle. *Note: Thiazides are contraindicated as they increase calcium reabsorption.* 3. **Prednisolone (Glucocorticoids):** These are specifically effective in hypercalcemia caused by Vitamin D toxicity, sarcoidosis, or lymphomas. They act by decreasing intestinal calcium absorption and inhibiting 1-alpha-hydroxylase activity. **Clinical Pearls for NEET-PG:** * **Immediate First Step:** The most crucial initial step in managing severe hypercalcemia is **aggressive IV hydration with 0.9% Normal Saline** to restore volume and enhance calcium excretion. * **Calcitonin:** Used for rapid reduction of calcium (works within hours) but is limited by **tachyphylaxis** (effect wears off after 48 hours). * **Cinacalcet:** A calcimimetic used specifically in secondary hyperparathyroidism (CKD) or parathyroid carcinoma. * **Denosumab:** A RANKL inhibitor used in refractory hypercalcemia of malignancy. * **Hemodialysis:** The treatment of choice for patients with severe hypercalcemia and concomitant heart failure or renal failure who cannot tolerate aggressive hydration.
Question 19: Syndrome X is not found in which of the following?
- A. Diabetes Mellitus Type II
- B. Dyslipidemia
- C. High triglycerides
- D. Weight loss (Correct Answer)
Explanation: Explanation: **Syndrome X**, now more commonly known as **Metabolic Syndrome** (or Insulin Resistance Syndrome), is a cluster of metabolic abnormalities that significantly increase the risk of cardiovascular disease and Type II Diabetes Mellitus. [1] **Why Weight Loss is the Correct Answer:** The hallmark of Metabolic Syndrome is **central (android) obesity** and insulin resistance. [1] Weight loss is actually a therapeutic goal and a protective factor, whereas **weight gain** (specifically an increased waist circumference) is a core diagnostic criterion. Therefore, weight loss is not a component of the syndrome. **Analysis of Incorrect Options:** * **Diabetes Mellitus Type II (Option A):** Insulin resistance is the pathophysiological backbone of Syndrome X. This leads to impaired glucose tolerance and eventually overt Type II Diabetes. [1] * **Dyslipidemia (Option B):** This is a broad term covering the lipid abnormalities found in the syndrome, characterized by a pro-atherogenic profile. * **High Triglycerides (Option C):** This is a specific diagnostic criterion (≥150 mg/dL). It is typically accompanied by **Low HDL** levels. **NEET-PG High-Yield Pearls:** To diagnose Metabolic Syndrome (per NCEP ATP III criteria), 3 out of the following 5 must be present: 1. **Waist Circumference:** >102 cm (M) or >88 cm (W). *Note: For Indians (Modified), it is >90 cm (M) and >80 cm (W).* 2. **Triglycerides:** ≥150 mg/dL. 3. **HDL Cholesterol:** <40 mg/dL (M) or <50 mg/dL (W). 4. **Blood Pressure:** ≥130/85 mmHg. 5. **Fasting Glucose:** ≥100 mg/dL. *Distinction:* Do not confuse "Syndrome X" (Metabolic) with **"Cardiac Syndrome X"** (Microvascular angina with normal epicardial coronaries).
Question 20: A 55-year-old woman with a history of severe depression and radical mastectomy for breast carcinoma one year ago presents with polyuria, nocturia, and excessive thirst. Laboratory values are as follows: Serum sodium 149 mEq/L, Serum potassium 3.6 mEq/L, Serum calcium 9.5 mg/dL, Glucose 110 mg/dL, BUN 30 mg/dL, Urine osmolarity 150 mOsm/kg. What is the most likely clinical diagnosis?
- A. Psychogenic polydipsia
- B. Renal glycosuria
- C. Hypercalcemia
- D. Diabetes insipidus (Correct Answer)
Explanation: ### Explanation The patient presents with the classic triad of **polyuria, nocturia, and polydipsia**, accompanied by **hypernatremia** (149 mEq/L) and **dilute urine** (Urine Osmolarity < 300 mOsm/kg). This clinical picture is diagnostic of **Diabetes Insipidus (DI)**. **1. Why Diabetes Insipidus is Correct:** In DI, there is either a deficiency of ADH (Central) or resistance to its action (Nephrogenic). This results in the inability of the kidneys to concentrate urine. The low urine osmolarity (150 mOsm/kg) in the presence of high serum sodium and elevated BUN (indicating mild dehydration) confirms that the kidneys are inappropriately excreting water. In this patient, the history of breast carcinoma suggests potential **metastasis to the posterior pituitary/hypothalamus**, a known cause of Central DI. **2. Why Other Options are Incorrect:** * **Psychogenic Polydipsia:** Patients typically present with **hyponatremia** (dilutional) because they ingest excessive water, which suppresses ADH. This patient is hypernatremic. * **Renal Glycosuria:** While glucose can cause osmotic diuresis, the patient’s blood glucose is normal (110 mg/dL). Without hyperglycemia, there is no significant osmotic pull from glucose to cause this degree of dilute polyuria. * **Hypercalcemia:** Although hypercalcemia can cause nephrogenic DI, this patient’s calcium level is **normal** (9.5 mg/dL), ruling it out as the primary cause. **3. NEET-PG High-Yield Pearls:** * **Diagnostic Cut-off:** Urine osmolarity < 300 mOsm/kg in the presence of serum osmolarity > 295 mOsm/kg or Sodium > 145 mEq/L points to DI. * **Water Deprivation Test:** Used to differentiate Psychogenic Polydipsia from DI. * **Desmopressin (DDAVP) Challenge:** Differentiates Central DI (urine osmolarity increases by >50%) from Nephrogenic DI (no significant increase). * **Common Metastases to Brain:** Lung > Breast > Melanoma. Breast cancer specifically has a predilection for the pituitary stalk.
Practice by Chapter
Diabetes Mellitus
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Thyroid Disorders
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Adrenal Gland Disorders
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Pituitary Disorders
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Calcium and Bone Metabolism
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Reproductive Endocrinology
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Lipid Disorders
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Endocrine Hypertension
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Multiple Endocrine Neoplasia
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Obesity and Metabolic Syndrome
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Neuroendocrine Tumors
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Endocrine Emergencies
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