Endocrinology Practice Questions

Q: In a patient with Turner syndrome (45, XO), what is the recommended hormone replacement therapy (HRT)?

Growth hormone + E+P. ***Growth hormone + E+P*** - **Growth hormone** is essential to improve final adult height in girls with Turner syndrome, as they commonly experience **short stature**. - **Estrogen (E)** and **progesterone (P)** replacement is crucial for the development of **secondary sexual characteristics** and to prevent long-term complications of estrogen deficiency, such as osteoporosis. *Estrogen* - While **estrogen** is a component of HRT for Turner syndrome, it is insufficient on its own for comprehensive management. - **Progesterone** is also necessary to induce cyclic bleeding and protect the uterine lining from unchecked estrogenic stimulation. *No HRT Needed* - This is incorrect as **HRT is medically necessary** for almost all individuals with Turner syndrome due to **gonadal dysgenesis** and resultant estrogen deficiency. - Without HRT, patients would not develop secondary sexual characteristics, would be at high risk for osteoporosis, and experience other long-term health issues. *HRT only after 45 years* - This is incorrect as HRT should be initiated much earlier, typically in **early adolescence** (around 12-14 years old), to mimic natural puberty. - Delaying HRT would prevent the development of secondary sexual characteristics and lead to significant **bone mineral density loss** during critical developmental years.

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: Which of the following conditions is most commonly associated with hypocalcemia in a child?

Vitamin D deficiency. ***Vitamin D deficiency*** - **Vitamin D deficiency** is the **most common cause** of hypocalcemia in the pediatric population worldwide, particularly in developing countries and at-risk populations (limited sun exposure, dark skin, exclusive breastfeeding without supplementation). - **Vitamin D** is crucial for **intestinal calcium absorption** and bone mineralization. - Severe deficiency leads to **rickets** and **hypocalcemia** due to impaired calcium uptake, with compensatory secondary hyperparathyroidism. *DiGeorge syndrome with normal parathyroid function* - **DiGeorge syndrome** (22q11.2 deletion) classically causes **hypocalcemia** due to **parathyroid hypoplasia or aplasia**, resulting in hypoparathyroidism. - However, **if parathyroid function is explicitly stated as normal**, the syndrome would NOT cause hypocalcemia, making this option incorrect as written. - The qualifier "with normal parathyroid function" is key—it eliminates the mechanism by which DiGeorge causes hypocalcemia. *Magnesium deficiency* - Severe **magnesium deficiency** can cause **hypocalcemia** by impairing **PTH secretion** and inducing **skeletal resistance to PTH**. - However, it is **uncommon** as a primary cause of hypocalcemia in the general pediatric population compared to vitamin D deficiency. *Hypoparathyroidism* - **Hypoparathyroidism** results in reduced **PTH levels**, leading to decreased renal calcium reabsorption and reduced vitamin D activation, causing **hypocalcemia**. - While it **directly** causes hypocalcemia, it is a **less common** condition than vitamin D deficiency in the general pediatric population, making vitamin D deficiency the most frequent cause overall.

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: 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.

Question 1

In a patient with Turner syndrome (45, XO), what is the recommended hormone replacement therapy (HRT)?

Accepted Answer

Growth hormone + E+P

Answer

No HRT Needed

Answer

HRT only after 45 years

Answer

Estrogen

Question 2

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 3

Which of the following conditions is most commonly associated with hypocalcemia in a child?

Accepted Answer

Vitamin D deficiency

Answer

DiGeorge syndrome with normal parathyroid function

Answer

Magnesium deficiency

Answer

Hypoparathyroidism

Question 4

Turner syndrome is maximally associated with ?

Accepted Answer

Coarctation of aorta

Answer

Horseshoe kidney

Answer

VSD

Answer

ASD

Question 5

Which condition is associated with congenital adrenal hyperplasia?

Accepted Answer

Female pseudohermaphroditism

Answer

Male pseudohermaphroditism

Answer

True pseudohermaphroditism

Answer

Sequential pseudohermaphroditism

Question 6

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 7

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 8

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 9

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 10

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

Endocrinology — MCQs

Endocrinology — MCQs

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