Endocrinology Practice Questions

Q: An 8-day-old male infant presents with vomiting, lethargy, dehydration, and features of shock. Clinical examination reveals hyperpigmentation of the genital skin and normal external genitalia. Blood tests reveal sodium of 124 mEq/L, potassium of 7 mEq/L, and hypoglycemia. What is the most likely diagnosis?

Congenital Adrenal Hyperplasia (CAH). ### Explanation The clinical presentation is classic for **Congenital Adrenal Hyperplasia (CAH)**, specifically the **salt-wasting form of 21-hydroxylase deficiency**. **1. Why CAH is the Correct Answer:** * **Pathophysiology:** A deficiency in 21-hydroxylase leads to impaired synthesis of cortisol and aldosterone. * **Salt-Wasting Crisis:** Low aldosterone causes sodium loss (hyponatremia) and potassium retention (hyperkalemia), leading to dehydration, vomiting, and shock. Low cortisol leads to hypoglycemia. * **Hyperpigmentation:** Low cortisol triggers a feedback increase in ACTH. Since ACTH and Melanocyte-Stimulating Hormone (MSH) share a common precursor (POMC), excess ACTH causes hyperpigmentation (noted here on the genitals). * **Genitalia:** In males, external genitalia appear normal because excess androgens do not cause malformations in males (unlike females, who present with ambiguous genitalia/virilization). **2. Why Other Options are Incorrect:** * **Adrenal Hemorrhage:** While it can cause adrenal insufficiency, it is usually associated with birth trauma, sepsis, or a palpable abdominal mass. It would not explain the generalized hyperpigmentation seen from birth. * **Acute Gastroenteritis:** While it causes vomiting and dehydration, it typically presents with *hypernatremia* or *isonatremia* and *hypokalemia*. It does not cause hyperpigmentation or hypoglycemia. * **Hyperaldosteronism:** This would cause the exact opposite electrolyte profile: hypernatremia and hypokalemia. **3. NEET-PG High-Yield Pearls:** * **Most common cause of CAH:** 21-hydroxylase deficiency (90-95%). * **Diagnostic Marker:** Elevated **17-hydroxyprogesterone (17-OHP)**. * **Karyotype:** In a female with CAH, the karyotype is 46,XX, but she presents with ambiguous genitalia (Prader staging). * **Management:** Immediate fluid resuscitation (Normal Saline) and IV Hydrocortisone.

Q: What is the most common cause of central precocious puberty in girls?

Idiopathic. **Explanation:** Precocious puberty is defined as the onset of secondary sexual characteristics before age 8 in girls and age 9 in boys. It is categorized into **Central (GnRH-dependent)** and **Peripheral (GnRH-independent)** types. **Why Idiopathic is correct:** In girls, the vast majority (80–90%) of central precocious puberty (CPP) cases are **idiopathic**. This means the hypothalamic-pituitary-gonadal axis is activated prematurely without an identifiable structural lesion. In contrast, CPP in boys is much more likely to be associated with an underlying Central Nervous System (CNS) pathology. **Analysis of Incorrect Options:** * **Exogenous estrogen:** This causes **peripheral** precocious puberty (pseudoprecocity). It suppresses GnRH, leading to low LH/FSH levels, unlike the elevated levels seen in central causes. * **Central nervous system tumor:** While tumors like hypothalamic hamartomas or gliomas are significant causes of CPP, they are statistically less common than idiopathic cases in girls. However, they are the most common cause of CPP in **boys**. * **Hypothyroidism:** Severe, untreated primary hypothyroidism can cause "Van Wyk-Grumbach syndrome," leading to precocious puberty (usually with delayed bone age), but it is a rare cause compared to idiopathic activation. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** GnRH stimulation test (CPP shows a pubertal LH response). * **Bone Age:** Characteristically advanced in CPP, leading to premature epiphyseal fusion and short adult stature. * **Treatment of Choice:** Long-acting GnRH agonists (e.g., Leuprolide) to desensitize the pituitary. * **Rule of Thumb:** Always perform an MRI of the brain in all boys with CPP and in girls with onset before age 6 to rule out CNS lesions.

Q: Klinfelter syndrome is characterized by the presence of an extra?

X-chromosome. **Explanation:** **Klinefelter Syndrome (KS)** is the most common sex chromosome aneuploidy in males, occurring in approximately 1 in 500 to 1,000 live male births. The hallmark of this condition is the presence of at least one **extra X-chromosome** in a male phenotype. 1. **Why Option A is Correct:** The classic genotype for Klinefelter syndrome is **47,XXY**. This occurs due to non-disjunction during meiosis (more commonly maternal than paternal). The presence of the extra X-chromosome leads to testicular dysgenesis, resulting in primary hypogonadism (low testosterone, high LH/FSH). 2. **Why Option B is Incorrect:** An extra Y-chromosome (47,XYY) results in **Jacob’s Syndrome**. These individuals are typically tall and may have behavioral issues but do not exhibit the testicular atrophy or gynecomastia seen in Klinefelter. 3. **Why Options C & D are Incorrect:** While mosaicism (e.g., 46,XY/47,XXY) or higher-order polysomy (48,XXXY) can occur, the defining feature remains the extra X-chromosome(s). **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Features:** Tall stature (long legs), small firm testes (pathognomonic), gynecomastia, and female-pattern hair distribution. * **Biochemical Profile:** Hypergonadotropic hypogonadism (↑ FSH, ↑ LH, ↓ Testosterone, ↑ Estradiol). * **Histology:** Hyalinization and fibrosis of seminiferous tubules with **Leydig cell hyperplasia** (clumping). * **Complications:** Increased risk of **Male Breast Cancer**, Germ cell tumors (mediastinal), and Systemic Lupus Erythematosus (SLE). * **Infertility:** It is a leading cause of non-obstructive azoospermia.

Q: A nineteen-year-old female with short stature, wide-spaced nipples, and primary amenorrhea most likely has which karyotype?

45, XO. ### Explanation The clinical presentation of **short stature, wide-spaced nipples (shield chest), and primary amenorrhea** in a female is the classic triad for **Turner Syndrome**. **1. Why 45, XO is correct:** Turner Syndrome is the most common sex chromosome abnormality in females, characterized by the complete or partial absence of one X chromosome. The lack of the second X chromosome leads to **gonadal dysgenesis** (streak ovaries), resulting in low estrogen levels, elevated gonadotropins (hypergonadotropic hypogonadism), and subsequent primary amenorrhea. Short stature is attributed to the loss of the **SHOX gene** located on the distal limb of the X chromosome. **2. Why the other options are incorrect:** * **47, XX + 18 (Edwards Syndrome):** This is an autosomal trisomy characterized by severe intellectual disability, micrognathia, low-set ears, and clenched fists with overlapping fingers. It is usually fatal within the first year of life. * **46, XXXY:** This is a rare variant of Klinefelter syndrome. While it presents with tall stature and hypogonadism, it occurs in **males**, not females. * **47, XXY (Klinefelter Syndrome):** This is the most common sex chromosome aneuploidy in **males**. It presents with tall stature, gynecomastia, small firm testes, and infertility, which does not match the female phenotype described. **3. Clinical Pearls for NEET-PG:** * **Most common cardiac defect:** Bicuspid aortic valve (most frequent); Coarctation of the aorta (highly specific). * **Renal anomaly:** Horseshoe kidney. * **Dermatological finding:** Lymphedema of hands and feet (at birth) and multiple pigmented nevi. * **Intelligence:** Usually normal, but may have difficulties with visuospatial organization. * **Karyotype variety:** 50% are 45,XO; others may be mosaics (e.g., 45,XO/46,XX) or have structural abnormalities of the X chromosome.

Q: What condition is likely in a newborn presenting with dry, rough skin, a big tongue and rough hair?

Congenital hypothyroidism. ***Congenital hypothyroidism*** - This condition is classically associated with signs of **cretinism** in newborns, including developmental delays, **dry/rough skin** (due to **myxedema**), and distinct facial features like **macroglossia** (big tongue). - The presentation of rough hair and generalized skin changes reflect reduced metabolic rate and accumulation of **glycosaminoglycans** in the dermis. *Prader-Willi syndrome* - Characterized by severe **neonatal hypotonia** and feeding difficulties followed by unremitting **hyperphagia** and obesity starting in early childhood. - The key features are related to the deletion of paternal chromosome 15 genes, and it does not typically present with the specific severe **myxedematous skin changes** seen here. *Edward syndrome* - Edward syndrome (**Trisomy 18**) is characterized by severe growth deficiency, **micrognathia**, **rocker-bottom feet**, overlapping fingers, and often severe congenital heart anomalies. - These findings are indicative of severe chromosomal abnormalities that typically result in distinct physical malformations, not primary hypothyroidism features such as **macroglossia** and widespread myxedema. *Galactosemia* - This is an inborn error of metabolism that usually presents after milk feeding starts, leading to poor feeding, **jaundice**, **hepatomegaly**, and subsequent formation of **cataracts**. - The initial clinical picture is dominated by metabolic decompensation, **sepsis (E. coli)**, and liver disease, not the classic physical features of thyroid hormone deficiency.

Q: Which of the following is not true in Turner Syndrome?

Prominent occiput. ***Prominent occiput*** - This physical feature is **NOT** associated with Turner Syndrome and is therefore the correct answer. - A prominent occiput is a classic distinguishing feature of **Trisomy 18 (Edwards Syndrome)**, not Turner syndrome. - Turner syndrome patients typically have normal occiput configuration, helping differentiate it from other chromosomal aneuploidies. *Incorrect - Short 4th metacarpals* - This is actually a **classic feature** of Turner Syndrome, known as the **metacarpal sign**. - Short 4th and 5th metacarpals are well-documented skeletal abnormalities in Turner syndrome. - On X-ray, extending a line along the 4th and 5th metacarpal heads normally passes distal to the 3rd metacarpal head, but in Turner syndrome it passes through or proximal to it. *Incorrect - Webbed neck* - This is a highly characteristic feature of Turner Syndrome, clinically known as **pterygium colli**. - Results from regression of fetal cystic hygromas (lymphatic malformations). - Strongly associated with the **45,X karyotype** and is a significant phenotypic marker. *Incorrect - Widely spaced hypoplastic nipples* - This describes the **shield chest** appearance, a key physical characteristic of Turner syndrome. - Part of the constellation of congenital developmental anomalies including broad chest with increased internipple distance. - Directly linked to the underlying chromosomal abnormality and developmental changes.

Q: A 5-year-old girl presents with vaginal bleeding and thelarche. An X-ray shows multiple cysts in long bones, and she has multiple hyper-pigmented spots. This presentation is suggestive of McCune Albright syndrome. What type of precocious puberty is associated with this syndrome?

Peripheral precocious puberty. ***Peripheral precocious puberty*** - McCune-Albright Syndrome is characterized by **gonadotropin-independent precocious puberty**, meaning it results from a direct overproduction of sex hormones (estrogen in girls) by the gonads or adrenal glands, independent of pituitary control. - The **fibrous dysplasia** (cysts in long bones), **café-au-lait spots**, and **endocrinopathies** like precocious puberty are classic features of this syndrome. *Central precocious puberty* - This type of precocious puberty is **gonadotropin-dependent**, meaning it is initiated by the activation of the hypothalamic-pituitary-gonadal (HPG) axis. - While central precocious puberty can occur in girls, it is not the primary mechanism behind the precocious puberty seen in McCune-Albright syndrome, which is driven by peripheral hormone production. *Adrenal hyperplasia* - While adrenal hyperplasia can cause precocious puberty (specifically, precocious pseudopuberty), it primarily leads to **virilization** in girls due to excess androgen production, which is not described in this case (vaginal bleeding and thelarche suggest estrogen excess). - McCune-Albright syndrome typically involves **ovarian cysts** that autonomously produce estrogen, rather than adrenal hyperplasia as the primary cause of precocious puberty. *Ovarian tumor* - An ovarian tumor could cause peripheral precocious puberty, as it can directly produce estrogen. - However, the overall clinical picture including **fibrous dysplasia** and **café-au-lait spots** points to McCune-Albright syndrome as the underlying diagnosis, where precocious puberty is often due to autonomously functioning ovarian cysts that are part of the syndrome, rather than a solitary neoplastic tumor as the sole cause.

Q: The image shows a child with virilisation and clitoromegaly. What laboratory finding is typical for this condition, assuming the most common enzyme defect?

Increased urinary sodium. ***Increased urinary sodium*** - **Congenital adrenal hyperplasia (CAH)** due to **21-hydroxylase deficiency** is the most common cause of virilization and clitoromegaly in female infants, accounting for >90% of CAH cases. - This enzyme defect blocks the conversion of 17-hydroxyprogesterone to 11-deoxycortisol, impairing both **cortisol and aldosterone synthesis**. - The lack of **aldosterone** (mineralocorticoid) results in a **salt-wasting crisis** with renal sodium loss, leading to **hyponatremia, hyperkalemia, and inappropriately elevated urinary sodium excretion** despite low serum sodium. - Among the given options, increased urinary sodium is the characteristic laboratory finding of the salt-wasting form (seen in ~75% of 21-hydroxylase deficiency cases). *Low urinary sodium* - Low urinary sodium would suggest effective renal sodium retention with intact aldosterone function. - This is contrary to the aldosterone deficiency seen in salt-wasting CAH, where the kidneys cannot retain sodium appropriately. *Increased plasma cortisol* - In 21-hydroxylase deficiency, the enzyme block **prevents cortisol synthesis**, leading to **decreased plasma cortisol** levels. - The low cortisol triggers increased ACTH secretion, which drives adrenal androgen overproduction (causing virilization) and accumulation of precursors like 17-hydroxyprogesterone. *Increased aldosterone* - **Aldosterone synthesis is severely impaired** in 21-hydroxylase deficiency, leading to **decreased or absent aldosterone** levels. - Increased aldosterone would cause sodium retention and potassium excretion—the opposite of the salt-wasting crisis observed in this condition.

Q: The following instrument is used for:

Hypogonadism. ***Hypogonadism*** - The image displays an **orchidometer**, specifically a Prader orchidometer, which is a medical instrument used to measure the **volume of the testes**. - Testicular volume measurement is crucial for diagnosing and monitoring conditions like **hypogonadism**, where testicular size can be reduced. - It is primarily used to assess **pubertal development** and detect **delayed or precocious puberty**. *Hypothyroidism* - Hypothyroidism is a condition caused by **underactive thyroid gland**, leading to low thyroid hormone production. - While it can cause various systemic symptoms, it is not primarily diagnosed or monitored using an orchidometer. *Hypoadrenalism* - Hypoadrenalism, or Addison's disease, is a condition where the **adrenal glands produce insufficient steroid hormones**. - Diagnosis involves **blood tests measuring hormone levels** (e.g., cortisol, aldosterone) and is unrelated to testicular volume measurement. *Soto syndrome* - **Soto syndrome** is a genetic overgrowth disorder characterized by **excessive physical growth** during childhood, along with intellectual disability and distinctive facial features. - Its diagnosis is based on **clinical features and genetic testing**, not testicular volume measurement. - While some overgrowth syndromes can have testicular findings, the orchidometer is not a primary diagnostic tool for Soto syndrome.

Question 1

An 8-day-old male infant presents with vomiting, lethargy, dehydration, and features of shock. Clinical examination reveals hyperpigmentation of the genital skin and normal external genitalia. Blood tests reveal sodium of 124 mEq/L, potassium of 7 mEq/L, and hypoglycemia. What is the most likely diagnosis?

Accepted Answer

Congenital Adrenal Hyperplasia (CAH)

Answer

Adrenal Haemorrhage

Answer

Acute Gastroenteritis with dehydration

Answer

Hyperaldosteronism

Question 2

What is the most common cause of central precocious puberty in girls?

Accepted Answer

Idiopathic

Answer

Exogenous estrogen

Answer

Central nervous system tumor

Answer

Hypothyroidism

Question 3

Klinfelter syndrome is characterized by the presence of an extra?

Accepted Answer

X-chromosome

Answer

Y chromosome

Answer

Both

Answer

None

Question 4

A nineteen-year-old female with short stature, wide-spaced nipples, and primary amenorrhea most likely has which karyotype?

Accepted Answer

45, XO

Answer

47, XX + 18

Answer

46XXXY

Answer

47, XXY

Question 5

In children with classical galactosemia, all the following are true except:

Accepted Answer

Elimination of galactose in the diet will not reverse cataract

Answer

E. coli neonatal sepsis is common

Answer

Galactose converts to galactitol, which is toxic to the brain

Answer

Children with the Duae variant of galactosemia are asymptomatic

Question 6

What condition is likely in a newborn presenting with dry, rough skin, a big tongue and rough hair?

Accepted Answer

Congenital hypothyroidism

Answer

Prader-Willi syndrome

Answer

Edward syndrome

Answer

Galactosemia

Question 7

Which of the following is not true in Turner Syndrome?

Accepted Answer

Prominent occiput

Answer

Short 4th metacarpals

Answer

Webbed neck

Answer

Widely spaced hypoplastic nipples

Question 8

A 5-year-old girl presents with vaginal bleeding and thelarche. An X-ray shows multiple cysts in long bones, and she has multiple hyper-pigmented spots. This presentation is suggestive of McCune Albright syndrome. What type of precocious puberty is associated with this syndrome?

Accepted Answer

Peripheral precocious puberty

Answer

Central precocious puberty

Answer

Adrenal hyperplasia

Answer

Ovarian tumor

Question 9

The image shows a child with virilisation and clitoromegaly. What laboratory finding is typical for this condition, assuming the most common enzyme defect?

Accepted Answer

Increased urinary sodium

Answer

Low urinary sodium

Answer

Increased plasma cortisol

Answer

Increased aldosterone

Question 10

The following instrument is used for:

Accepted Answer

Hypogonadism

Answer

Hypothyroidism

Answer

Hypoadrenalism

Answer

Soto syndrome

Endocrinology — MCQs

Endocrinology — MCQs

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