Endocrinology Practice Questions

Q: Which of the following is the MOST characteristic cause of precocious puberty?

McCune-Albright syndrome. ***McCune-Albright syndrome*** - This syndrome is characterized by the **classic triad** of **fibrous dysplasia of bone**, **café-au-lait spots**, and **precocious puberty**. - It causes **peripheral (gonadotropin-independent) precocious puberty** due to **activating mutation in the GNAS gene**, leading to autonomous hormone production. - This is one of the **most characteristic and well-defined causes** of peripheral precocious puberty in pediatric endocrinology. *Hypothyroidism* - **Severe, long-standing primary hypothyroidism** can paradoxically cause precocious puberty (Van Wyk-Grumbach syndrome). - This occurs due to **receptor overlap** between TSH and gonadotropin receptors, but it is a **much rarer cause**. - Typically presents with **delayed bone age** (unlike typical precocious puberty which has advanced bone age). *CNS irradiation* - Cranial irradiation can cause **central precocious puberty** by damaging hypothalamic-pituitary axis. - However, it is an **acquired iatrogenic cause** rather than a primary disease entity classically associated with precocious puberty. - More commonly causes **growth hormone deficiency** and other endocrine deficits. *None of the options* - Incorrect, as McCune-Albright syndrome is a well-established, characteristic cause of precocious puberty.

Q: Turner syndrome is maximally associated with ?

Coarctation of aorta. **Coarctation of aorta** - **Coarctation of the aorta** is the most common cardiovascular abnormality associated with **Turner syndrome**, occurring in 5-20% of affected individuals [1]. - It is a **narrowing of the aorta**, typically near the ductus arteriosus, which can lead to hypertension and other cardiovascular complications [1]. *Horseshoe kidney* - While **renal anomalies** are common in Turner syndrome (occurring in 30-60%), **horseshoe kidney** is not the single most prevalent or *maximally associated* malformation. - Other renal abnormalities like duplicated collecting systems and pelvic kidneys are also frequently observed. *VSD* - **Ventricular septal defect (VSD)** is a type of congenital heart defect, but it is not as frequently associated with Turner syndrome as coarctation of the aorta [2]. - VSDs are among the most common congenital heart defects overall but are not the leading cardiovascular anomaly specific to Turner syndrome [3]. *ASD* - **Atrial septal defect (ASD)** is another congenital heart anomaly, but it is not the *maximally associated* cardiovascular defect in Turner syndrome. - Coarctation of the aorta and bicuspid aortic valve are more characteristic cardiovascular findings in this condition [1].

Q: Which condition is associated with congenital adrenal hyperplasia?

Female pseudohermaphroditism. ***Female pseudohermaphroditism*** - In **21-hydroxylase deficiency**, the most common form of CAH, virilization of a female fetus occurs due to excessive **androgen production** [2], [3]. - This leads to ambiguous genitalia in genetically female (XX) infants, presenting as **female pseudohermaphroditism** [2]. *Male pseudohermaphroditism* - This condition occurs when a **genetically male individual (XY)** has external genitalia that are undervirilized or ambiguous. - It is typically caused by inadequate **androgen synthesis** or action, such as in **androgen insensitivity syndrome**, which is not the primary presentation of CAH [2]. *True pseudohermaphroditism* - This term refers to individuals who possess both **ovarian and testicular tissue**, either in separate gonads or as ovotestes [1], [2]. - It is distinct from CAH, where gonadal tissue is uniform (either ovaries or testes), but the external genitalia are ambiguous due to hormonal imbalances [2]. *Sequential pseudohermaphroditism* - This term is not a recognized medical classification for conditions like CAH. - It does not describe a specific developmental anomaly of the reproductive system related to adrenal function.

Q: Which of the following is true regarding precocious puberty:

Sexual maturity is attained early. ***Sexual maturity is attained early*** - **Precocious puberty** is defined by the development of secondary sexual characteristics significantly earlier than the average age. - This early onset of puberty means that affected individuals reach **sexual maturity** at a younger chronological age. *Mental function is increased* - Precocious puberty does not inherently lead to an increase in **mental function** or cognitive abilities. - While hormonal changes can influence mood and behavior, they do not enhance intelligence. *Reproductive function is absent* - Precocious puberty implies the premature activation of the **hypothalamic-pituitary-gonadal axis**, leading to the appearance of secondary sexual characteristics and, in many cases, the potential for **reproductive function**. - Girls, for example, can experience early menarche and boys can produce sperm, meaning fertility is not absent but rather accelerated. *Body proportions remain unchanged* - Precocious puberty often results in changes in **body proportions**, particularly due to the early closure of epiphyseal plates. - Although there is an initial growth spurt, the premature fusion of growth plates can lead to a shorter-than-average adult height.

Q: What is the mode of inheritance for the most common form of hypophosphatemic rickets?

X-Linked Dominant (XD). ***X-Linked Dominant (XD)*** - The most common form of hypophosphatemic rickets is **X-linked hypophosphatemic rickets (XLH)**, which is inherited in an X-linked dominant pattern. - This condition is caused by mutations in the **PHEX gene** on the X chromosome, leading to impaired phosphate reabsorption in the kidneys. *Autosomal Recessive (AR)* - While some rare forms of hypophosphatemic rickets exist with **autosomal recessive** inheritance, they are not the most common. - These forms typically involve mutations in genes affecting phosphate transport or vitamin D metabolism, distinct from the primary defect in XLH. *Autosomal Dominant (AD)* - There are also rare **autosomal dominant** forms of hypophosphatemic rickets, such as hereditary hypophosphatemic rickets with hypercalciuria (HHRH) or autosomal dominant hypophosphatemic rickets (ADHR). - However, these are less common than the X-linked dominant form (XLH). *X-Linked Recessive (XR)* - **X-linked recessive** inheritance typically affects males more severely and exclusively, with carrier females usually unaffected or mildly affected. - In X-linked dominant conditions like XLH, both males and females are affected, though females may exhibit variable expressivity.

Q: What is the target HbA1c level for a 2-5 year old child with diabetes mellitus (DM)?

< 8 %. ***< 8 %*** - For children aged 2-5 years with diabetes, the current **ADA (American Diabetes Association) 2024 Standards of Care** recommend a target HbA1c of **< 8%** to balance optimal glycemic control with safety. - This target acknowledges the challenges of managing glucose levels in very young children, including their **inconsistent eating patterns**, difficulty communicating hypoglycemic symptoms, and **increased risk of severe hypoglycemia** which can impair neurodevelopment. - The target prioritizes **safety** while still promoting good metabolic control to prevent long-term diabetic complications. *< 7 %* - A target HbA1c of **< 7%** is typically recommended for **older adolescents and adults** with diabetes who can recognize and manage hypoglycemic symptoms more effectively. - This stringent target is often challenging and potentially dangerous for young children aged 2-5 years, significantly increasing the risk of **frequent and severe hypoglycemic episodes** which can have long-term neurocognitive consequences. *< 9 %* - While a target of < 9% may have been recommended in **older guidelines**, it is now considered **too lenient** for children aged 2-5 years according to current evidence-based recommendations. - Current guidelines advocate for **< 8%** as it provides better long-term glycemic control without substantially increasing hypoglycemia risk when diabetes is managed appropriately with modern insulin regimens and monitoring technologies. *< 6 %* - A target HbA1c of **< 6%** is considered very aggressive and is rarely recommended for any pediatric age group, especially not for young children with diabetes. - Achieving such a low target would require intensive insulin regimens, leading to an unacceptably high risk of **severe hypoglycemia**, impaired quality of life, and potential neurodevelopmental harm in this vulnerable age group.

Q: Which of the following is not a feature of hypothyroidism in infancy?

Premature closure of posterior fontanelle. ***Premature closure of posterior fontanelle*** - Delayed closure of fontanelles, particularly the **posterior fontanelle**, is a characteristic feature of **congenital hypothyroidism** due to impaired bone maturation. - Therefore, **premature closure** would be inconsistent with a diagnosis of hypothyroidism in infancy. *Coarse facies* - **Coarse facial features** such as a broad nasal bridge, puffy eyelids, and a protuberant tongue are common manifestations of **congenital hypothyroidism** due to the accumulation of glycosaminoglycans. - This is a direct consequence of the metabolic derangements caused by insufficient thyroid hormone. *Umbilical hernia* - An **umbilical hernia** is frequently observed in infants with hypothyroidism, resulting from generalized **hypotonia** and incomplete closure of the umbilical ring. - The reduced muscle tone characteristic of the condition contributes to this physical finding. *Constipation* - **Constipation** is a common gastrointestinal symptom in infants with hypothyroidism, caused by **decreased gut motility** secondary to reduced thyroid hormone levels. - This is a clinical indicator of the systemic metabolic slowing associated with the condition.

Q: In Precocious puberty, the age limit for girls is?

8 years. ***8 years*** - Precocious puberty is defined clinically by the development of secondary sexual characteristics in girls before the age of **8 years old**. - This age cut-off is based on population studies and clinical consensus to identify children needing further evaluation for underlying causes. *10 years* - This age is generally considered within the **normal range** for the onset of puberty, not precocious. - Pubertal development typically begins between ages 8 and 13 in girls. *9 years* - While close to the precocious threshold, **9 years** is still considered within the typical window for the onset of puberty. - The established clinical definition for precocious puberty in girls is explicitly _before_ the age of 8. *11 years* - This age is well within the **normal range** for pubertal onset and progression in girls. - Development of secondary sexual characteristics at this age would not be considered precocious.

Q: An XX baby presenting with male genitalia (penis and scrotum) is likely due to which of the following conditions?

High level of testosterone in maternal blood. ***High level of testosterone in maternal blood*** - An **XX baby** (genetically female) presenting with **fully masculinized external genitalia** (penis and scrotum) indicates significant **androgen exposure** during the critical period of sexual differentiation (8-12 weeks of gestation). - While the most common cause is **congenital adrenal hyperplasia (CAH)** due to fetal androgen excess, **maternal sources of androgens** can also cause complete masculinization. - Maternal causes include **virilizing tumors** (e.g., luteoma of pregnancy, Krukenberg tumor, arrhenoblastoma), **exogenous androgen administration**, or **maternal CAH**. - High sustained maternal testosterone crosses the placenta and causes **virilization of female fetus**, which can range from clitoromegaly to complete male phenotype. - This is the **only medically correct option** among the choices given, though CAH (not listed) would be the most common cause overall. *Klinefelter syndrome* - **47, XXY karyotype** - genetically male due to presence of Y chromosome with SRY gene. - Presents as phenotypic male, not relevant to an **XX individual**. - Features include hypogonadism, infertility, tall stature, and gynecomastia. *Turner syndrome* - **45, X karyotype** - monosomy X, genetically and phenotypically female. - Presents with **female external genitalia**, streak gonads, short stature, webbed neck. - Cannot explain masculinized genitalia in any scenario. *None of the options* - This is incorrect because **high level of testosterone in maternal blood** is a documented cause of XX virilization with male phenotype, though less common than fetal CAH.

Q: A 5-year-old boy presents with pubic hair development, being tall, and having increased pigmentation of his genitalia and phallic enlargement, along with a blood pressure of 130/90 mmHg. Measurement of which of the following diagnostic hormones would be most likely to indicate a diagnosis of congenital adrenal hyperplasia?

Increase 17-hydroxyprogesterone. ***Increase 17 beta-hydroxyprogesterone*** - The clinical presentation of **precocious puberty** (pubic hair, phallic enlargement), **hypertension**, and **hyperpigmentation** strongly suggests **congenital adrenal hyperplasia (CAH)**. - In most common forms of CAH (e.g., 21-hydroxylase deficiency), there is an inability to convert **17-hydroxyprogesterone** to 11-deoxycortisol, leading to its significant accumulation. *Increase cortisol* - In CAH due to enzyme deficiencies, the adrenal glands are unable to synthesize sufficient **cortisol**, leading to its **decrease**, not an increase. - The low cortisol then triggers increased **ACTH** release, driving the overproduction of adrenal androgens and precursors. *Increase aldosterone* - Only in specific forms of CAH (e.g., 17-alpha-hydroxylase deficiency) would **aldosterone** be increased (due to shunting of precursors), but this is less common and would typically present with hypokalemia rather than hyperpigmentation. - In the more common 21-hydroxylase deficiency, **aldosterone can be decreased** (salt-wasting form), or normal, leading to hyponatremia and hyperkalemia. *Increase 11-deoxycortisol* - An increase in **11-deoxycortisol** is characteristic of **11-beta-hydroxylase deficiency**, another form of CAH. - While this form also causes **hypertension** and **virilization**, the most prominent precursor elevated in the majority of CAH cases (21-hydroxylase deficiency) is **17-hydroxyprogesterone**.

Question 1

Which of the following is the MOST characteristic cause of precocious puberty?

Accepted Answer

McCune-Albright syndrome

Answer

Hypothyroidism

Answer

CNS irradiation

Answer

None of the options

Question 2

Turner syndrome is maximally associated with ?

Accepted Answer

Coarctation of aorta

Answer

Horseshoe kidney

Answer

VSD

Answer

ASD

Question 3

Which condition is associated with congenital adrenal hyperplasia?

Accepted Answer

Female pseudohermaphroditism

Answer

Male pseudohermaphroditism

Answer

True pseudohermaphroditism

Answer

Sequential pseudohermaphroditism

Question 4

Which of the following is true regarding precocious puberty:

Accepted Answer

Sexual maturity is attained early

Answer

Mental function is increased

Answer

Reproductive function is absent

Answer

Body proportions remain unchanged

Question 5

What is the mode of inheritance for the most common form of hypophosphatemic rickets?

Accepted Answer

X-Linked Dominant (XD)

Answer

Autosomal Recessive (AR)

Answer

Autosomal Dominant (AD)

Answer

X-Linked Recessive (XR)

Question 6

What is the target HbA1c level for a 2-5 year old child with diabetes mellitus (DM)?

Accepted Answer

< 8 %

Answer

< 7 %

Answer

< 9 %

Answer

< 6 %

Question 7

Which of the following is not a feature of hypothyroidism in infancy?

Accepted Answer

Premature closure of posterior fontanelle

Answer

Umbilical hernia

Answer

Constipation

Answer

Coarse facies

Question 8

In Precocious puberty, the age limit for girls is?

Accepted Answer

8 years

Answer

10 years

Answer

9 years

Answer

11 years

Question 9

An XX baby presenting with male genitalia (penis and scrotum) is likely due to which of the following conditions?

Accepted Answer

High level of testosterone in maternal blood

Answer

Turner syndrome

Answer

None of the options

Answer

Klinefelter syndrome

Question 10

A 5-year-old boy presents with pubic hair development, being tall, and having increased pigmentation of his genitalia and phallic enlargement, along with a blood pressure of 130/90 mmHg. Measurement of which of the following diagnostic hormones would be most likely to indicate a diagnosis of congenital adrenal hyperplasia?

Accepted Answer

Increase 17-hydroxyprogesterone

Answer

Increase cortisol

Answer

Increase aldosterone

Answer

Increase 11 deoxycortisol

Endocrinology — MCQs

Endocrinology — MCQs

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