Endocrinology — MCQs
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A 10-year-old boy has a fracture of the femur. Biochemical evaluation revealed a hemoglobin level of 11.5 g/dL and an erythrocyte sedimentation rate of 18 mm in the first hour. Serum calcium levels were 12.8 mg/dL, serum phosphorus levels were 2.3 mg/dL, alkaline phosphatase levels were 28 KA units, and blood urea levels were 32 mg/dL. Which of the following is the most probable diagnosis in his case?
A 45-year-old man with a recent history of bizarre behavior is seen by a psychiatrist. On physical examination, the patient appears moderately obese with mild hypertension, facial acne, and fat accumulation in the supraclavicular fossae. Laboratory studies demonstrate neutrophilic leukocytosis, decreased lymphocytes, and absence of eosinophils, along with mild hypokalemia and mild metabolic alkalosis. The fasting serum glucose is within the reference range, but the OGTT shows glucose concentrations > 200 mg/dL. Laboratory studies also show a free urinary cortisol of 156 mg/24 hours. Which of the following questions would be of most help in establishing a diagnosis?
What is the primary reason for infertility in Sertoli cell only syndrome?
True regarding glucose tolerance test are all except:
A 13-year-old child visits the OPD with complaints of not attaining menarche, and has a karyotype of 46,XX. On examination, there is clitoromegaly. Which enzyme is likely deficient?
Which of the following is the most common feature of thyrotoxicosis?
While investigating a case of gynecomastia, all of the following hormone levels are estimated, except:
Retinopathy is most likely to be seen with which of the following conditions?
Which of the following conditions is not associated with Cushing syndrome?
Which one of the following is the earliest manifestation of Cushing's syndrome?
Endocrinology Indian Medical PG Practice Questions and MCQs
Question 1611: A 10-year-old boy has a fracture of the femur. Biochemical evaluation revealed a hemoglobin level of 11.5 g/dL and an erythrocyte sedimentation rate of 18 mm in the first hour. Serum calcium levels were 12.8 mg/dL, serum phosphorus levels were 2.3 mg/dL, alkaline phosphatase levels were 28 KA units, and blood urea levels were 32 mg/dL. Which of the following is the most probable diagnosis in his case?
- A. Renal rickets
- B. Hyperparathyroidism (Correct Answer)
- C. Skeletal dysplasia
- D. Nutritional rickets
Explanation: ***Hyperparathyroidism*** - The patient exhibits **hypercalcemia** (12.8 mg/dL), **hypophosphatemia** (2.3 mg/dL), and an **elevated alkaline phosphatase** (28 KA units), which are classic hallmarks of hyperparathyroidism. - The femur fracture suggests **bone demineralization** due to chronically elevated parathyroid hormone levels, leading to increased bone turnover. Primary hyperparathyroidism is indicated by significant hypercalcemia (calcium > 11.4 mg/dL) and may lead to complications like osteoporosis [2]. *Nutritional rickets* - This condition is typically characterized by **hypocalcemia** or **normal calcium** levels, **hypophosphatemia**, and an **elevated alkaline phosphatase** due to defective bone mineralization from vitamin D deficiency [1]. - The presented case has frank **hypercalcemia**, which rules out nutritional rickets. *Renal rickets* - Also known as renal osteodystrophy, this condition primarily results in **hypocalcemia**, **hyperphosphatemia** (due to impaired phosphate excretion), and **elevated alkaline phosphatase** [1]. - The patient's **normal blood urea** and **hypercalcemia** make renal rickets unlikely. *Skeletal dysplasia* - This is a broad term for genetic disorders affecting bone and cartilage development, often leading to abnormal bone shape and fractures. - While it can cause fractures, it does not typically present with the specific constellation of **hypercalcemia** and **hypophosphatemia** seen in this patient's biochemical profile.
Question 1612: A 45-year-old man with a recent history of bizarre behavior is seen by a psychiatrist. On physical examination, the patient appears moderately obese with mild hypertension, facial acne, and fat accumulation in the supraclavicular fossae. Laboratory studies demonstrate neutrophilic leukocytosis, decreased lymphocytes, and absence of eosinophils, along with mild hypokalemia and mild metabolic alkalosis. The fasting serum glucose is within the reference range, but the OGTT shows glucose concentrations > 200 mg/dL. Laboratory studies also show a free urinary cortisol of 156 mg/24 hours. Which of the following questions would be of most help in establishing a diagnosis?
- A. Are you experiencing muscle weakness?
- B. Do you have a family history of endocrine neoplasia?
- C. Are you experiencing shortness of breath?
- D. Are you receiving corticosteroids for some other disease? (Correct Answer)
Explanation: ***Are you receiving corticosteroids for some other disease?*** - The patient's presentation including **obesity**, **hypertension**, **facial acne**, **supraclavicular fat accumulation** (buffalo hump), **neutrophilic leukocytosis**, **lymphopenia**, **eosinopenia**, **hypokalemia**, **metabolic alkalosis**, and **impaired glucose tolerance** with **elevated urinary free cortisol** are all highly suggestive of **Cushing's syndrome** [1]. - Exogenous corticosteroid use is the most common cause of Cushing's syndrome (iatrogenic Cushing's syndrome), and directly asking about it is crucial to differentiate it from endogenous causes [2]. *Are you experiencing muscle weakness?* - **Proximal muscle weakness** is a common symptom in Cushing's syndrome due to the catabolic effects of excess cortisol on muscle protein [1]. - While it's a helpful diagnostic symptom, it describes a manifestation of the disease rather than helping to determine its etiology, especially when differentiating between endogenous and exogenous causes. *Are you experiencing shortness of breath?* - **Shortness of breath** is not a direct or common symptom of Cushing's syndrome itself. - While hypertension and obesity associated with Cushing's can contribute to cardiovascular or respiratory issues in some cases, it's not a primary or specific finding. *Do you have a family history of endocrine neoplasia?* - A family history of **endocrine neoplasia** (e.g., Multiple Endocrine Neoplasia type 1 or 2, or familial isolated pituitary adenoma) might suggest an inherited predisposition to certain endocrine tumors, some of which could potentially cause endogenous Cushing's syndrome (e.g., pituitary adenoma leading to ACTH-dependent Cushing's disease) [3]. - However, considering the overall clinical picture, the initial step should be to rule out the most common cause of Cushing's symptoms, which is exogenous corticosteroid use, before delving into rare genetic causes of endogenous Cushing's.
Question 1613: What is the primary reason for infertility in Sertoli cell only syndrome?
- A. Too many Sertoli cells inhibit spermatogenesis via inhibin
- B. Proper blood-testis barrier is not established
- C. Sufficient numbers of spermatozoa are not produced
- D. The absence of germ cells in this condition. (Correct Answer)
Explanation: ***The absence of germ cells in this condition.*** - **Sertoli cell only syndrome** is characterized by the complete or near-complete absence of germ cells in the seminiferous tubules [2]. - Since germ cells are the precursors to spermatozoa, their absence directly results in the inability to produce sperm, leading to **infertility** [1]. *Too many Sertoli cells inhibit spermatogenesis via inhibin* - While Sertoli cells produce **inhibin B**, which negatively regulates FSH, the primary issue in Sertoli cell only syndrome is the lack of germ cells, not an overabundance of Sertoli cells or excessive inhibin production causing inhibition [1]. - The syndrome is defined by the *absence of germ cells*, not by a functional alteration of Sertoli cells due to their quantity. *Proper blood-testis barrier is not established* - The **blood-testis barrier (BTB)** is formed by tight junctions between Sertoli cells and is crucial for creating an immunological barrier for developing germ cells [2]. - While disruptions in BTB integrity can impair spermatogenesis, the primary cause of infertility in Sertoli cell only syndrome is the *absence of the cells that the barrier is meant to protect* (germ cells), rather than a failure of the barrier itself. *Sufficient numbers of spermatozoa are not produced* - This statement is true as a *result* of infertility, but it does not explain the *primary reason* for it. - The lack of spermatozoa is a direct consequence of the **absence of germ cells**, which are necessary precursors for sperm production [1].
Question 1614: True regarding glucose tolerance test are all except:
- A. Diagnosis of diabetes mellitus can be established
- B. Glucose levels are checked after 2 hours
- C. 1 gram of glucose/kg body weight is administered (Correct Answer)
- D. Can be done in fasting as well as post prandial state
Explanation: ***1 gram of glucose/kg body weight is administered*** - For an oral glucose tolerance test (OGTT) in adults, the standard dose is **75 grams of anhydrous glucose**, irrespective of body weight. [3] - In children, the recommended dose is **1.75 g/kg body weight** up to a maximum of 75 grams. *Glucose levels are checked after 2 hours* - This statement is **true** for a standard oral glucose tolerance test, where post-load glucose levels are typically measured at 2 hours to assess glucose metabolism. [3] - The **2-hour plasma glucose value** is a key diagnostic criterion for diabetes and impaired glucose tolerance. [1] *Diagnosis of diabetes mellitus can be established* - This statement is **true**, as an OGTT is a standard diagnostic tool for diabetes mellitus and impaired glucose tolerance. [1] - A 2-hour plasma glucose level of **200 mg/dL (11.1 mmol/L) or higher** during an OGTT confirms a diagnosis of diabetes. [1] *Can be done in fasting as well as post prandial state* - This statement refers to the **timing of the blood samples**, not the preparation for the test itself. Fasting plasma glucose is measured before glucose ingestion, while post-prandial levels are assessed after the glucose load. [2] - However, for an OGTT to be valid, the patient must be in a **fasting state** for at least 8 hours prior to the test to establish a baseline.
Question 1615: A 13-year-old child visits the OPD with complaints of not attaining menarche, and has a karyotype of 46,XX. On examination, there is clitoromegaly. Which enzyme is likely deficient?
- A. 17-alpha hydroxylase
- B. 21-alpha hydroxylase (Correct Answer)
- C. 11-alpha hydroxylase
- D. 3-beta hydroxysteroid dehydrogenase
Explanation: ***21-alpha hydroxylase*** - A deficiency in **21-alpha hydroxylase** leads to **Congenital Adrenal Hyperplasia (CAH)**, shunting precursors towards **androgen production**. - In a 46,XX individual, this results in **virilization** such as **clitoromegaly** and **primary amenorrhea** due to excess androgens suppressing gonadotropin release and ovarian function. *17-alpha hydroxylase* - Deficiency in **17-alpha hydroxylase** in a 46,XX individual would lead to impaired sex steroid synthesis but **excess mineralocorticoids**, causing **hypertension** and **hypokalemia**. - While it causes **primary amenorrhea** due to lack of estrogen, it typically presents with **female external genitalia** that are underdeveloped, not virilized with clitoromegaly. *11-alpha hydroxylase* - There is no known functional enzyme called **11-alpha hydroxylase** in the steroid synthesis pathway. The relevant enzyme is **11-beta hydroxylase**, which, when deficient, leads to **CAH** with virilization and hypertension. - Assuming it refers to 11-beta hydroxylase, deficiency would cause **virilization** in 46,XX females but also lead to **hypertension** due to accumulation of 11-deoxycorticosterone, which is not mentioned in the presentation. *3-beta hydroxysteroid dehydrogenase* - Deficiency of **3-beta hydroxysteroid dehydrogenase** impairs the synthesis of **all classes of adrenal steroids** (glucocorticoids, mineralocorticoids, and sex steroids). - In 46,XX individuals, it leads to **females with ambiguous genitalia** (due to accumulation of DHEA) and **salt wasting**, but typically does not cause overt clitoromegaly and amenorrhea in the manner seen with 21-hydroxylase deficiency.
Question 1616: Which of the following is the most common feature of thyrotoxicosis?
- A. Anxiety (Correct Answer)
- B. Weight loss
- C. Menorrhagia
- D. Palpitation
Explanation: ***Anxiety*** - **Anxiety** and **nervousness** are highly prevalent neurobehavioral symptoms in thyrotoxicosis, occurring in a majority of patients due to increased adrenergic activity [1]. - Patients often present with **irritability**, **restlessness**, and difficulty concentrating, which are all manifestations of anxiety. *Palpitation* - While very common, **palpitations** (tachycardia) are a cardiac manifestation due to increased heart rate and contractility, but are not universally present or the sole dominant symptom in all cases [2]. - Many patients experience **palpitations** but may present with other symptoms more prominently in the initial stages. *Weight loss* - **Weight loss** despite an increased appetite is a classic symptom of thyrotoxicosis due to an elevated metabolic rate [1], [2]. - However, not all patients experience significant **weight loss**, especially those with milder or subclinical disease. *Menorrhagia* - **Menorrhagia** (heavy menstrual bleeding) is typically *not* a feature of thyrotoxicosis; in fact, **oligomenorrhea** (infrequent periods) or **amenorrhea** (absence of periods) are more commonly associated due to hormonal imbalances. - Thyroid hormones play a role in regulating the menstrual cycle, and excess thyroid hormone often leads to lighter or absent periods.
Question 1617: While investigating a case of gynecomastia, all of the following hormone levels are estimated, except:
- A. Lutenizing hormone
- B. Prolactin
- C. Follicle stimulating hormone (Correct Answer)
- D. None of the options
Explanation: ***Follicle stimulating hormone*** - While **FSH** levels can be assessed in cases of infertility or hypogonadism, they are generally **not a primary assessment** for gynecomastia. - The direct hormonal imbalance causing gynecomastia typically involves other hormones like testosterone, estrogen, LH, and prolactin. *Lutenizing hormone* - **LH** levels are crucial in assessing **gonadal function** and identifying the cause of altered testosterone production, which is directly linked to gynecomastia [1]. - Elevated or suppressed LH can indicate primary or secondary hypogonadism affecting the **testosterone-estrogen balance**. *Prolactin* - **Prolactin** levels are important to rule out **hyperprolactinemia**, which can lead to hypogonadism and subsequently gynecomastia [1]. - A **prolactinoma** (prolactin-secreting tumor) can suppress GnRH, leading to reduced testosterone and an increased estrogen-to-androgen ratio [1]. *None of the options* - This option is incorrect because there is a specific hormone (FSH) among the choices that is **less commonly estimated** in the initial workup for gynecomastia compared to LH and prolactin. - The workup for gynecomastia commonly involves assessment of other hormones like **testosterone** and **estrogen** along with LH and prolactin [1].
Question 1618: Retinopathy is most likely to be seen with which of the following conditions?
- A. Gestational diabetes
- B. Juvenile diabetes started before puberty
- C. Type 2 diabetes of 8 years duration (Correct Answer)
- D. Type 1 diabetes of 5 years duration
Explanation: **Type 2 diabetes of 8 years duration** - **Diabetic retinopathy** is a common microvascular complication of diabetes mellitus [1]. - The risk of retinopathy increases with the **duration of diabetes** and the **severity of hyperglycemia**, making an 8-year duration with type 2 diabetes a significant risk factor [1]. *Type 1 diabetes of 5 years duration* - While type 1 diabetes can cause retinopathy, a 5-year duration is generally considered relatively short for the development of significant retinopathy, especially in early stages. - The risk of retinopathy in **Type 1 diabetes** becomes more pronounced after 10-15 years, though it can occur earlier. *Gestational diabetes* - **Gestational diabetes** is a temporary condition occurring during pregnancy and does not typically lead to chronic complications like retinopathy. - Retinopathy is rare in gestational diabetes because the disease duration is short and usually resolves post-partum. *Juvenile diabetes started before puberty* - **Juvenile diabetes** is synonymous with Type 1 diabetes [2]. Although early onset of diabetes increases lifetime risk, the duration of diabetes is a more critical factor for retinopathy development. - Without a specified duration, it's less predictive than an established longer duration of Type 2 diabetes.
Question 1619: Which of the following conditions is not associated with Cushing syndrome?
- A. Oat cell carcinoma of lung
- B. Pituitary adenoma
- C. Adrenal carcinoma
- D. Medulloblastoma (Correct Answer)
Explanation: ***Medulloblastoma*** - **Medulloblastoma** is a primary **brain tumor** that arises in the cerebellum and is not typically associated with hormone production leading to Cushing syndrome. - Its symptoms are primarily neurological, related to increased **intracranial pressure** or cerebellar dysfunction, not systemic metabolic disturbances. *Adrenal carcinoma* - **Adrenal carcinoma** can directly produce excessive amounts of **cortisol**, leading to Cushing syndrome (specifically **primary adrenal Cushing's**) [1]. - This is a rare but aggressive tumor of the adrenal cortex. *Oat cell carcinoma of lung* - Also known as **small cell lung carcinoma**, this tumor can produce **ectopic ACTH** (adrenocorticotropic hormone), leading to paraneoplastic Cushing syndrome [1]. - The ectopic ACTH stimulates the adrenal glands to produce excess cortisol [1]. *Pituitary adenoma* - A **pituitary adenoma** that secretes ACTH is the most common cause of **Cushing's disease** (a specific type of Cushing syndrome) [1]. - This excess ACTH then stimulates the adrenal glands to overproduce cortisol [1].
Question 1620: Which one of the following is the earliest manifestation of Cushing's syndrome?
- A. Loss of diurnal variation (Correct Answer)
- B. Increased ACTH
- C. Increased plasma cortisol
- D. Increased urinary metabolites of cortisol
Explanation: ***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.
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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