Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 271: Hypocalcemia in a child may be associated with

A. DiGeorge syndrome
B. Magnesium deficiency
C. Hypoparathyroidism
D. All of the options (Correct Answer)

Explanation: ***All of the options*** - **Hypocalcemia** can stem from various causes, and all the listed conditions (DiGeorge syndrome, magnesium deficiency, and hypoparathyroidism) are known to cause it. - A comprehensive understanding of potential etiologies is crucial for accurate diagnosis and treatment of hypocalcemia in children. *Digeorge syndrome* - **DiGeorge syndrome** is a genetic disorder associated with abnormal development of the **thymus** and **parathyroid glands**, leading to **hypoparathyroidism** and subsequent hypocalcemia. - This condition is characterized by a deletion on **chromosome 22q11.2**, resulting in various clinical manifestations including **cardiac defects** and **immune deficiencies**. *Magnesium deficiency* - **Magnesium deficiency (hypomagnesemia)** can impair the release of **parathyroid hormone (PTH)** and reduce target organ responsiveness to PTH, leading to **hypocalcemia**. - Adequate magnesium levels are essential for the proper functioning of the **parathyroid glands** and calcium homeostasis. *Hypoparathyroidism* - **Hypoparathyroidism** is a condition where the **parathyroid glands** produce insufficient amounts of **parathyroid hormone (PTH)**, which is crucial for regulating calcium levels. - Insufficient PTH leads to decreased reabsorption of calcium in the kidneys and reduced calcium release from bones, resulting in **hypocalcemia**.

Question 272: Following are the features of cretinism, except

A. Normal intelligence (Correct Answer)
B. Characteristic facial features
C. Pot-belly
D. Stunted growth

Explanation: ***Normal intelligence*** - **Cretinism** (congenital hypothyroidism) is characterized by **severe mental retardation** if left untreated during critical developmental periods. - Normal intelligence is **not** a feature; rather, impaired cognitive development is a hallmark of the condition. *Characteristic facial features* - Patients with cretinism often present with **coarse facial features**, including a **puffy face**, broad nose, and thick lips. - These distinct features are a diagnostic clue for untreated congenital hypothyroidism. *Pot — belly* - A **protuberant abdomen** (pot-belly) is a common sign in infants and children with cretinism. - This is often accompanied by **umbilical hernia** due to generalized hypotonia. *Stunted growth* - **Dwarfism** or severely stunted growth is a prominent feature of cretinism due to the critical role of thyroid hormones in skeletal development and linear growth. - Delayed bone maturation and short stature are expected.

Question 273: Treatment for childhood hypothyroidism is with -

A. TSH
B. Propylthiouracil
C. Levothyroxine (Correct Answer)
D. T3

Explanation: ***Correct: Levothyroxine*** - **Levothyroxine** is synthetic **thyroxine (T4)**, the standard hormone replacement therapy for childhood hypothyroidism - It is **well-absorbed orally**, has a **long half-life**, and provides stable thyroid hormone levels - Once administered, it is converted to **T3 (the active form)** in peripheral tissues, ensuring steady thyroid hormone supply - **Preferred in children** for consistent growth and neurodevelopment *Incorrect: TSH* - **TSH (Thyroid-Stimulating Hormone)** is produced by the pituitary gland to stimulate thyroid hormone production - In **primary hypothyroidism**, TSH levels are *elevated* due to lack of negative feedback - TSH is a **diagnostic marker**, not a therapeutic agent for hormone replacement *Incorrect: Propylthiouracil* - **Propylthiouracil** is an **anti-thyroid drug** used to treat **hyperthyroidism** (excessive thyroid hormone) - It works by *inhibiting* thyroid hormone synthesis - Using it in hypothyroidism would **worsen** the condition by further reducing thyroid hormone levels *Incorrect: T3* - **T3 (triiodothyronine)** is the more metabolically active form of thyroid hormone - It has a **shorter half-life** and causes more **fluctuating hormone levels** - **Not preferred** for long-term replacement in children due to difficulty maintaining stable levels - Most levothyroxine (T4) is naturally converted to T3 *in vivo*, providing adequate T3 without direct supplementation

Question 274: A one-year-old child presents with short stature, lethargy, and constipation. Clinical examination shows a palpable goiter. Laboratory investigations revealed a low T4 and elevated TSH. Which of the following is the most likely diagnosis?

A. Thyroid Dyshormonogenesis (Correct Answer)
B. Central Hypothyroidism
C. Thyroid Dysgenesis
D. TSH Receptor Blocking Antibody

Explanation: ***Thyroid Dyshormonogenesis*** - This condition involves a defect in the **synthesis of thyroid hormones**, leading to **hypothyroidism** despite a physically normal or enlarged gland (goiter). - The combination of **goiter (palpable)** with **low T4** and **elevated TSH** in an infant points to the thyroid gland's inability to produce hormones effectively, prompting increased TSH stimulation. *Central Hypothyroidism* - Characterized by **low TSH** (or inappropriately normal TSH) alongside **low T4**, indicating a problem with the pituitary or hypothalamus. - A **goiter would not typically be present** as the thyroid gland is not being excessively stimulated; the child presents with an elevated TSH. *Thyroid Dysgenesis* - This typically presents with an **absent or underdeveloped thyroid gland**, meaning a **goiter would not be palpable**. - While it causes **low T4** and **elevated TSH**, the presence of a palpable goiter rules out dysgenesis. *TSH Receptor Blocking Antibody* - These antibodies block the TSH receptor, leading to **atrophic thyroiditis** and **hypothyroidism**, but typically without a goiter. - The thyroid gland is unable to respond to TSH, but it does not usually cause the gland to grow.

Question 275: 17-OH progesterone level in congenital adrenal hyperplasia in 1 year old child (in ng/dL)-

A. <150
B. 150-300
C. >600 (Correct Answer)
D. 300-600

Explanation: ***>600 ng/dL*** - In **classic congenital adrenal hyperplasia (CAH)** due to **21-hydroxylase deficiency**, a 17-OH progesterone level greater than 600 ng/dL is highly indicative, especially in a 1-year-old. - This significantly elevated level reflects the **blocked conversion** of 17-OH progesterone to 11-deoxycortisol in the adrenal steroid synthesis pathway. *<150 ng/dL* - This level is considered **normal** for 17-OH progesterone in a 1-year-old child and would rule out classic CAH. - Normal concentrations indicate an **intact 21-hydroxylase enzyme** pathway, allowing for proper cortisol synthesis. *150-300 ng/dL* - While not normal, this range might suggest **non-classic or attenuated CAH**, where the enzyme deficiency is partial, and the elevation is less pronounced than in classic forms. - For classic CAH in an infant or young child, a significantly higher elevation would be expected. *300-600 ng/dL* - This range is also **suggestive of CAH**, but in most cases of classic 21-hydroxylase deficiency in infancy, the 17-OH progesterone levels are considerably higher. - Levels within this range might be seen in less severe forms of the disorder or under specific testing conditions, but **>600 ng/dL** is more characteristic for classic CAH in this age group.

Question 276: Delayed puberty is seen in -

A. Hypothyroidism
B. Turner's syndrome
C. Chronic disease
D. All of the options (Correct Answer)

Explanation: ***All of the options*** - Delayed puberty can be a symptom of multiple underlying conditions including **hypothyroidism**, **Turner's syndrome**, and **chronic diseases**. - All these conditions can interfere with the normal hormonal and developmental pathways required for timely pubertal onset. *Hypothyroidism* - **Thyroid hormones** are crucial for normal growth and development, including sexual maturation. - Insufficient thyroid hormone levels can lead to a general slowing of metabolic processes and thus **delayed puberty**. *Turner's syndrome* - This is a chromosomal disorder (45,XO) primarily affecting females, characterized by the absence of one X chromosome. - It often results in **gonadal dysgenesis** (poorly developed ovaries), leading to **primary ovarian failure** and a failure to produce sex hormones necessary for puberty. *Chronic disease* - Many chronic illnesses, such as **inflammatory bowel disease**, **cystic fibrosis**, **renal failure**, or **diabetes mellitus**, can cause **delayed puberty**. - This is often due to the overall physiological stress, chronic inflammation, nutritional deficiencies, and altered hormone metabolism associated with long-term illness.

Question 277: Congenital adrenal hyperplasia most commonly presents as

A. 46,XY DSD
B. Ovotesticular DSD
C. 46,XX DSD with virilization (Correct Answer)
D. 46,XY DSD with undervirilization

Explanation: ***46,XX DSD with virilization*** (formerly female pseudohermaphroditism) - This is the **most common presentation** of congenital adrenal hyperplasia (CAH), particularly due to **21-hydroxylase deficiency**, which accounts for >90% of CAH cases. - Affects genetically female (46,XX) individuals with excess **androgens** produced by hyperplastic adrenal glands leading to **virilization** of external genitalia. - Clinical features include **clitoromegaly, labioscrotal fusion**, and varying degrees of masculinization, while **internal female organs (uterus, ovaries, fallopian tubes) remain normal**. - This is the classic presentation that brings CAH to clinical attention in newborn screening programs. *46,XY DSD* (formerly 46,XY intersex) - This terminology refers to conditions where genetically male individuals (46,XY) have atypical genital development. - Common causes include **androgen insensitivity syndrome** or disorders of testosterone synthesis (5α-reductase deficiency, 17β-hydroxysteroid dehydrogenase deficiency). - CAH in 46,XY individuals typically presents with **isosexual precocious pseudopuberty** (early virilization) in simple virilizing forms or **salt-wasting adrenal crisis** in severe forms, not undervirilization. *Ovotesticular DSD* (formerly true hermaphroditism) - Very rare condition where an individual has **both ovarian and testicular tissue**, either as separate gonads or combined as ovotestes. - Often involves complex chromosomal patterns including **46,XX/46,XY mosaicism** or 46,XX with SRY translocation. - Not related to CAH pathophysiology, which involves enzymatic defects in steroidogenesis. *46,XY DSD with undervirilization* (formerly male pseudohermaphroditism) - Occurs when 46,XY individuals have **undervirilized or ambiguous external genitalia** due to impaired androgen synthesis or action. - Causes include disorders of testicular development, androgen biosynthesis defects, or **androgen insensitivity**. - While CAH can affect males, it causes **excess androgens** leading to precocious puberty, not undervirilization.

Question 278: A 1-month old baby present with frequent vomiting and failure to thrive. There are features of moderate dehydration. Blood sodium in 122 mEq/l and potassium is 6.1 mEq/l. The most likely diagnosis is?

A. 11β-hydroxylase deficiency
B. 21-hydroxylase deficiency (Correct Answer)
C. Gitelman syndrome
D. Bartter syndrome

Explanation: ***21-hydroxylase deficiency*** - This condition presents in infancy with **salt-wasting adrenal crisis** due to impaired cortisol and aldosterone synthesis, leading to **hyponatremia**, **hyperkalemia**, **dehydration**, and **vomiting**. - The deficiency in 21-hydroxylase blocks the synthesis of **aldosterone**, causing sodium loss and potassium retention, consistent with the electrolyte abnormalities. *11β-hydroxylase deficiency* - This deficiency causes an accumulation of **11-deoxycorticosterone (DOC)**, which has mineralocorticoid activity, leading to **hypertension** and **hypokalemia**, rather than hyponatremia and hyperkalemia. - While it can cause virilization, the electrolyte imbalance is distinctly different from the case presented. *Gitelman syndrome* - This is a **renal tubulopathy** characterized by reabsorptive defects in the distal convoluted tubule, leading to **hypokalemia**, **metabolic alkalosis**, **hypomagnesemia**, and **hypocalciuria**. - It would not typically present with severe hyponatremia or hyperkalemia in a neonate with salt wasting. *Bartter syndrome* - This is a **renal tubulopathy** affecting the thick ascending limb of the loop of Henle, resulting in significant salt loss, **hypokalemia**, **metabolic alkalosis**, and **hypercalciuria**. - Like Gitelman syndrome, it is associated with hypokalemia, which contradicts the hyperkalemia seen in the patient.

Question 279: Adrenarche is the maturation of the adrenal cortex leading to increased androgen production. Adrenarche typically starts at the age of:

A. 7 (Correct Answer)
B. 8
C. 11
D. 12

Explanation: ***7*** - **Adrenarche** typically begins around **6 to 8 years of age**, with some earlier maturation seen in African American children. - This process involves the maturation of the adrenal cortex, leading to increased production of **adrenal androgens** like DHEA and DHEAS. *8* - While 8 years is within the general range, **7 years of age** is often cited as a more precise average onset for adrenarche. - The onset of adrenarche marks the development of **pubic and axillary hair** (pubarche and axillarche) and **body odor**, preceding gonadarche. *11* - An age of 11 years is generally considered the average onset of **gonadarche** (true puberty), which involves the activation of the hypothalamic-pituitary-gonadal axis. - **Adrenarche** precedes gonadarche by several years and is a separate maturational process of the adrenal glands. *12* - By 12 years of age, most children have already undergone **adrenarche** and are well into the stages of gonadarche, experiencing significant pubertal changes. - This age is typically associated with peak pubertal development, including **growth spurts** and more pronounced secondary sexual characteristics.

Question 280: A child with decreased levels of LH, FSH and Testosterone presents with delayed puberty. Which of the following is the most likely Diagnosis

A. Klinefelter's syndrome
B. Kallman's syndrome (Correct Answer)
C. Testicular infection
D. Androgen Insensitivity Syndrome

Explanation: ***Kallman's syndrome*** - **Kallmann's syndrome** is characterized by **isolated hypogonadotropic hypogonadism**, meaning the hypothalamus fails to produce **GnRH**, leading to low LH and FSH, and consequently low testosterone, causing delayed puberty. - A key distinguishing feature is the association with **anosmia or hyposmia** (impaired sense of smell) due to abnormal migration of olfactory neurons and GnRH-producing neurons. *Klinefelter's syndrome* - This condition is characterized by **primary hypogonadism** (testicular failure) due to an extra X chromosome (47,XXY), leading to **high LH and FSH** in an attempt to stimulate the failing testes. - Although testosterone is low and puberty is delayed, the **elevated gonadotropins** differentiate it from Kallmann's syndrome. *Testicular infection* - An infection like **orchitis** can lead to testicular damage and *primary hypogonadism*, resulting in low testosterone. - However, similar to Klinefelter's, this would typically cause **elevated LH and FSH** due to the lack of negative feedback from the testes. *Androgen Insensitive syndrome* - In **Androgen Insensitivity Syndrome (AIS)**, testosterone levels are typically **normal or even elevated**, but the body's cells are unable to respond to androgens due to defective receptors. - This condition presents with a female phenotype despite a 46,XY karyotype, and **gonadotropin levels (LH and FSH) are usually normal to high**, not decreased.

Practice by Chapter

Disorders of Growth

Practice Questions

Thyroid Disorders

Practice Questions

Disorders of Puberty

Practice Questions

Adrenal Disorders

Practice Questions

Diabetes Mellitus in Children

Practice Questions

Disorders of Calcium and Phosphate Metabolism

Practice Questions

Disorders of Sexual Development

Practice Questions

Hypoglycemia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Pituitary Disorders

Practice Questions

Multiple Endocrine Neoplasia Syndromes

Practice Questions

Endocrine Emergencies

Practice Questions

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