Endocrinology Practice Questions

Q: A 15-year-old boy with cystic fibrosis presents with a 3-6 kg weight loss over the past month, unaccompanied by changes in his pulmonary and gastrointestinal symptoms. Which of the following is most suspected?

Diabetes mellitus. ### Explanation **Correct Option: D. Diabetes Mellitus** The most likely diagnosis is **Cystic Fibrosis-Related Diabetes (CFRD)**. In Cystic Fibrosis (CF), thick secretions lead to progressive scarring and destruction of the pancreatic islet cells, causing a deficiency in insulin secretion. * **Why it fits:** Weight loss in a CF patient who is otherwise stable (no increase in cough, sputum, or malabsorption) is a classic red flag for CFRD. As insulin is an anabolic hormone, its deficiency leads to catabolism and weight loss despite adequate caloric intake. CFRD is the most common extra-pulmonary complication of CF, affecting nearly 20% of adolescents and 40-50% of adults. **Analysis of Incorrect Options:** * **A. Bronchogenic Carcinoma:** While CF increases the risk of certain malignancies, lung cancer is rare in a 15-year-old. Furthermore, weight loss from malignancy would typically be accompanied by worsening pulmonary symptoms. * **B. Eating Disorder:** While possible in any adolescent, the physiological link between CF and pancreatic endocrine failure makes CFRD a much more high-yield and likely clinical suspicion. * **C. Biliary Cirrhosis:** While CF-associated liver disease occurs, it usually presents with hepatosplenomegaly, jaundice, or portal hypertension rather than isolated rapid weight loss without GI distress. **NEET-PG High-Yield Pearls:** * **Screening:** Annual screening for CFRD using the **Oral Glucose Tolerance Test (OGTT)** should begin at **age 10** for all CF patients. * **Pathophysiology:** It is a unique entity—not Type 1 (not autoimmune) and not Type 2 (primarily insulin deficiency, not resistance). * **Treatment:** **Insulin** is the only recommended treatment. Oral hypoglycemic agents are generally not effective. * **Clinical Clue:** Unexplained decline in pulmonary function or weight loss in a CF patient is the most common presentation of CFRD.

Q: What is the most common preventable cause of mental retardation?

Congenital hypothyroidism. **Explanation:** The correct answer is **Congenital Hypothyroidism**. **1. Why Congenital Hypothyroidism is correct:** Congenital hypothyroidism is the **most common preventable cause** of intellectual disability (mental retardation) worldwide. Thyroid hormones are critical for fetal and neonatal brain development, specifically for neuronal migration, myelination, and synaptogenesis. While the damage is irreversible once it occurs, it is entirely preventable if detected early through **newborn screening** and treated with Levothyroxine within the first 2–4 weeks of life. **2. Why the other options are incorrect:** * **Down’s Syndrome (Trisomy 21):** This is the most common **genetic/chromosomal** cause of mental retardation. However, it is not "preventable" in the medical sense once conception has occurred. * **Fragile X Syndrome:** This is the most common **inherited** cause of mental retardation (affecting the FMR1 gene). Like Down’s syndrome, it cannot be reversed or prevented through postnatal medical intervention. * **Rett’s Syndrome:** A neurodevelopmental disorder (primarily in females due to MECP2 mutation) characterized by a period of normal growth followed by loss of purposeful hand skills and speech. It is a genetic condition and not preventable. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of Congenital Hypothyroidism:** Thyroid dysgenesis (Ectopy is the most common specific type). * **Clinical Features:** Most neonates are asymptomatic at birth due to maternal T4. Early signs include a large posterior fontanelle, prolonged physiological jaundice, hoarse cry, and umbilical hernia. * **Screening:** Ideally done via heel-prick test for TSH between **48–72 hours** of life to avoid the physiological neonatal TSH surge.

Q: A short 4th metatarsal is seen in which of the following conditions?

Turner syndrome. **Explanation:** The correct answer is **Turner Syndrome (45, XO)**. **1. Why Turner Syndrome is correct:** A short 4th metatarsal (and/or 4th metacarpal) is a classic skeletal manifestation of Turner syndrome, known as **Archibald’s sign**. This occurs due to premature epiphyseal fusion of the bones. When the patient makes a fist, the knuckle of the 4th digit appears recessed rather than prominent. This is a high-yield clinical marker used to differentiate Turner syndrome from other causes of primary amenorrhea. **2. Analysis of Incorrect Options:** * **Patau Syndrome (Trisomy 13):** Characterized by midline defects (holoprosencephaly, cleft lip/palate), polydactyly, and microphthalmia. It does not typically feature isolated shortening of the 4th metatarsal. * **Richards Syndrome:** A rare neurodegenerative disorder characterized by mental retardation, sensorineural hearing loss, and ketoaciduria. It is not associated with specific metatarsal shortening. * **Down’s Syndrome (Trisomy 21):** Common skeletal findings include clinodactyly (incurving of the 5th finger), a wide gap between the 1st and 2nd toes (sandal gap), and hypoplasia of the middle phalanx of the 5th digit, but not a short 4th metatarsal. **3. Clinical Pearls for NEET-PG:** * **Archibald’s Sign:** Shortening of the 4th metacarpal/metatarsal. * **Differential Diagnosis for Short 4th Metacarpal:** Turner syndrome, Pseudohypoparathyroidism (Albright Hereditary Osteodystrophy), and Pseudo-pseudohypoparathyroidism. * **Other Turner Skeletal Signs:** Cubitus valgus (increased carrying angle), Madelung deformity (wrist), and Shield chest (widely spaced nipples). * **Most Common Cardiac Defect:** Bicuspid aortic valve (most common overall); Coarctation of the aorta (classic association).

Q: A child presents with stunted growth, a protuberant abdomen, short stature, and mental retardation. Deficiency of which of the following is the most likely cause?

Thyroxine. The clinical presentation described is a classic case of **Congenital Hypothyroidism (Cretinism)**. ### **Why Thyroxine is the Correct Answer** Thyroxine ($T_4$) is essential for the normal development of the skeletal system and the central nervous system during infancy. Deficiency leads to: * **Mental Retardation:** Thyroid hormones are critical for myelination and neuronal migration in the brain. * **Stunted Growth & Short Stature:** Due to impaired bone maturation and delayed epiphyseal closure. * **Protuberant Abdomen:** Caused by hypotonia of the abdominal muscles and often associated with an umbilical hernia and constipation. * **Other features:** Macroglossia (large tongue), coarse facies, and prolonged neonatal jaundice. ### **Why Other Options are Incorrect** * **Growth Hormone (GH):** GH deficiency causes "Pituitary Dwarfism." While it leads to short stature and a "doll-like" face, it **does not** cause mental retardation or a protuberant abdomen. * **Vitamin D:** Deficiency causes Rickets. While it can cause a "pot-belly" (due to hypotonia) and growth retardation, it is not typically associated with mental retardation. * **Parathyroid Hormone (PTH):** Deficiency (Hypoparathyroidism) leads to hypocalcemia, tetany, and seizures, but not the classic triad of cretinism. ### **NEET-PG High-Yield Pearls** * **Most common cause of Congenital Hypothyroidism:** Thyroid dysgenesis (Ectopy is the most common specific type). * **Most common preventable cause of mental retardation:** Congenital Hypothyroidism. * **Early Sign:** A posterior fontanelle >0.5 cm in a newborn should raise suspicion. * **Diagnosis:** Best screened via **TSH levels** (usually >20 mU/L) in the neonatal period. * **Treatment:** Levothyroxine must be started within the first 2 weeks of life to prevent permanent neurocognitive deficits.

Q: What is the most common gene involved in Noonan syndrome?

PTPN11. **Explanation:** **Noonan Syndrome** is an autosomal dominant disorder characterized by short stature, congenital heart defects, and distinct facial features. It is often referred to as the "Male Turner Syndrome," though it affects both sexes and has a normal karyotype. 1. **Why PTPN11 is correct:** The most common genetic cause of Noonan Syndrome (occurring in approximately **50% of cases**) is a germline mutation in the **PTPN11** gene located on chromosome 12. This gene encodes **SHP-2**, a protein tyrosine phosphatase that plays a critical role in the **RAS-MAPK signaling pathway**. Mutations in this pathway (collectively called "RASopathies") lead to gain-of-function signaling, resulting in the clinical manifestations of the syndrome. 2. **Analysis of Incorrect Options:** * **PTCN11 & PTCN22:** These are distractor options with incorrect prefixes. There are no major clinical syndromes associated with genes by these names in standard medical literature. * **PTPN22:** While this gene belongs to the same family, it is primarily associated with an increased risk of **autoimmune diseases** (such as Type 1 Diabetes, Rheumatoid Arthritis, and SLE) rather than developmental syndromes like Noonan. **High-Yield Clinical Pearls for NEET-PG:** * **Cardiac Findings:** The most common cardiac lesion is **Pulmonary Stenosis** (dysplastic valve), followed by Hypertrophic Cardiomyopathy (HCM). * **Facial Features:** Hypertelorism, downward slanting palpebral fissures, low-set posteriorly rotated ears, and a webbed neck. * **Hematology:** Patients often have a predisposition to bleeding diathesis and **Juvenile Myelomonocytic Leukemia (JMML)**. * **Differential:** Unlike Turner Syndrome (45,XO), Noonan patients are usually fertile (though males may have cryptorchidism) and have a normal 46,XX or 46,XY karyotype.

Q: A baby girl presents with bilateral inguinal masses, thought to be hernias but are found to be testes in the inguinal canals. Which karyotype would you expect to find in the child?

46,XY. ### Explanation **Correct Answer: B. 46,XY** **Concept:** The clinical presentation describes a classic case of **Androgen Insensitivity Syndrome (AIS)**, formerly known as Testicular Feminization Syndrome. In AIS, there is a mutation in the androgen receptor gene. Although the individual has a **46,XY karyotype** and functional testes that produce testosterone and Anti-Müllerian Hormone (AMH), the peripheral tissues cannot respond to androgens [1]. 1. **Testicular Development:** The presence of the SRY gene on the Y chromosome ensures the development of testes. 2. **Phenotype:** Because the body cannot respond to testosterone/DHT, external genitalia develop along female lines (default pathway). 3. **Clinical Clue:** The "inguinal hernias" in a phenotypic female infant are actually **undescended testes** located in the inguinal canal or labia majora. AMH causes regression of the uterus and fallopian tubes, leading to a blind-ending vaginal pouch. --- **Analysis of Incorrect Options:** * **A. 46,XX:** This is a normal female karyotype. While inguinal hernias can occur in females (containing ovaries), they would not contain histologically confirmed testes. * **C & D. 46,XXY / 47,XXY (Klinefelter Syndrome):** These individuals have a male phenotype (small testes, gynecomastia, tall stature) because they respond to androgens. They do not present as phenotypic females with inguinal masses in infancy. --- **High-Yield NEET-PG Pearls:** * **Most common cause of primary amenorrhea with absent uterus:** AIS (46,XY) or Müllerian Agenesis (46,XX). * **AIS vs. Müllerian Agenesis:** In AIS, testosterone levels are in the normal male range and pubic/axillary hair is absent or sparse. * **Management:** Testes are usually left in situ until after puberty to allow for natural estrogenization (via peripheral aromatization of testosterone), then removed to prevent **Gonadoblastoma/Dysgerminoma**.

Q: A child presents with learning disabilities. On examination, horseshoe kidney and streak gonads are noted. What is your diagnosis?

Turner's syndrome. **Explanation:** The clinical triad of **learning disabilities, horseshoe kidney, and streak gonads** is a classic presentation of **Turner’s Syndrome (45, XO)**. **Why Turner’s Syndrome is Correct:** Turner’s syndrome occurs due to complete or partial monosomy of the X chromosome. * **Streak Gonads:** The absence of the second X chromosome leads to accelerated oocyte atresia, replacing normal ovarian tissue with fibrous "streak" tissue, resulting in primary amenorrhea and hypergonadotropic hypogonadism. * **Horseshoe Kidney:** This is the most common renal anomaly in Turner’s (seen in ~10-15% of cases). * **Neuropsychiatric features:** While global IQ is usually normal, these children often face specific learning disabilities, particularly in visuospatial processing and mathematics. **Why Other Options are Incorrect:** * **Klinefelter’s Syndrome (47, XXY):** Presents in males with small, firm testes, gynecomastia, and tall stature. They do not have streak gonads or a high incidence of horseshoe kidneys. * **Noonan’s Syndrome:** Often called "Male Turner’s" due to similar features (webbed neck, short stature), but it is autosomal dominant. Key differentiators: it affects both sexes, features **Right-sided** heart defects (Pulmonary Stenosis), and patients usually have **normal** gonads/fertility. * **Fragile-X Syndrome:** The most common cause of inherited intellectual disability in males. Characterized by macro-orchidism (large testes), not streak gonads. **High-Yield Clinical Pearls for NEET-PG:** * **Most common Cardiac Anomaly:** Bicuspid Aortic Valve (overall); Coarctation of Aorta (classic association). * **Lymphedema:** Present at birth (hand/foot swelling) due to lymphatic hypoplasia. * **Short Stature:** Attributed to the loss of the **SHOX gene**. * **Dermatoglyphics:** Increased total ridge count on fingertips.

Q: Hypothyroidism in infancy is characterized by which of the following findings, EXCEPT?

Hyperthermia. **Explanation:** Congenital hypothyroidism (CH) results in a generalized slowing of metabolic processes and delayed physical development. **Why Hyperthermia is the correct answer:** Hypothyroidism leads to a **decreased basal metabolic rate (BMR)** and reduced thermogenesis. Consequently, infants with hypothyroidism typically present with **hypothermia** and cold intolerance, not hyperthermia. Hyperthermia is more characteristic of hyperthyroidism (thyroid storm). **Analysis of incorrect options:** * **Constipation:** Thyroid hormones are essential for normal gut motility. Deficiency leads to decreased peristalsis, making constipation one of the earliest and most common signs. * **Coarse Facies:** Due to the accumulation of glycosaminoglycans (myxedema) in the subcutaneous tissues, infants develop a puffy face, macroglossia (large tongue), and a flattened nasal bridge. * **Wide open cranial sutures:** Thyroid hormone is critical for bone maturation. Deficiency causes delayed ossification, resulting in large anterior and posterior fontanelles and wide cranial sutures. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Thyroid dysgenesis (Ectopy is the most frequent specific type). * **Earliest Sign:** Prolonged physiological jaundice (due to delayed glucuronyl transferase activity). * **Other Key Features:** Hoarse cry, umbilical hernia, hypotonia ("floppy baby"), and developmental delay. * **Diagnosis:** Newborn screening (increased TSH, decreased T4). * **Radiology:** Absence of the distal femoral epiphysis at birth is a strong indicator of in-utero hypothyroidism.

Q: Which of the following is true in cretinism?

All of these. **Explanation:** Cretinism, or **Congenital Hypothyroidism**, is a condition of severe thyroid hormone deficiency present at birth. Thyroid hormones ($T_3$ and $T_4$) are critical for metabolic processes, skeletal growth, and neurodevelopment. * **Option A (Prolonged physiological jaundice):** Thyroid hormones are essential for the maturation of the hepatic enzyme **UDP-glucuronyltransferase**. Deficiency leads to delayed conjugation of bilirubin, resulting in indirect hyperbilirubinemia that persists beyond the typical 10–14 days. * **Option B (Common in iodine deficiency):** While "sporadic cretinism" is usually due to thyroid dysgenesis, **"endemic cretinism"** occurs in geographical areas with severe iodine deficiency. It remains the most common cause of preventable intellectual disability worldwide. * **Option C (Delayed skeletal development):** Thyroid hormones stimulate osteoblast activity and epiphyseal maturation. Deficiency leads to delayed bone age, retarded linear growth (short stature), and characteristic **epiphyseal dysgenesis** (stippled epiphysis). Since all three clinical features are hallmark signs of the condition, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Prolonged jaundice or feeding difficulties. * **Classic Triad:** Coarse facies, protuberant tongue (macroglossia), and umbilical hernia. * **Diagnosis:** Newborn screening (best done at 48–72 hours) showing **High TSH** and **Low $T_4$**. * **Radiology:** Absence of the **distal femoral epiphysis** at birth (normally appears at 36 weeks gestation) is a strong indicator of prenatal hypothyroidism. * **Treatment:** Levothyroxine (10–15 μg/kg/day). Treatment must start within 2 weeks of birth to prevent permanent intellectual disability.

Question 1

A 15-year-old boy with cystic fibrosis presents with a 3-6 kg weight loss over the past month, unaccompanied by changes in his pulmonary and gastrointestinal symptoms. Which of the following is most suspected?

Accepted Answer

Diabetes mellitus

Answer

Bronchogenic carcinoma

Answer

Eating disorder

Answer

Biliary cirrhosis

Question 2

What is the most common preventable cause of mental retardation?

Accepted Answer

Congenital hypothyroidism

Answer

Down's syndrome

Answer

Rett's syndrome

Answer

Fragile X syndrome

Question 3

A 15-day-old male neonate presented with failure to thrive, recurrent vomiting, and symptoms of shock. On examination, severe dehydration is noted. He has normal genitalia along with precocious development of pubic hair, phallic enlargement, and accelerated skeletal maturation. The child's blood pressure was normal. Lab findings revealed hyponatremia and hypokalemia, increased serum 17-hydroxyprogesterone, and increased urinary pregnanetriol. A biopsy from the adrenal gland was taken. Which of the following is the most likely enzyme deficiency in this patient?

Accepted Answer

21-hydroxylase deficiency

Answer

11-hydroxylase deficiency

Answer

3-beta-hydroxysteroid dehydrogenase deficiency

Answer

17-hydroxylase deficiency

Question 4

A short 4th metatarsal is seen in which of the following conditions?

Accepted Answer

Turner syndrome

Answer

Patau syndrome

Answer

Richards syndrome

Answer

Down's syndrome

Question 5

A child presents with stunted growth, a protuberant abdomen, short stature, and mental retardation. Deficiency of which of the following is the most likely cause?

Accepted Answer

Thyroxine

Answer

Growth hormone

Answer

Vitamin D

Answer

Parathyroid hormone

Question 6

What is the most common gene involved in Noonan syndrome?

Accepted Answer

PTPN11

Answer

PTCN11

Answer

PTPN22

Answer

PTCN22

Question 7

A baby girl presents with bilateral inguinal masses, thought to be hernias but are found to be testes in the inguinal canals. Which karyotype would you expect to find in the child?

Accepted Answer

46,XY

Answer

46,XX

Answer

46,XXY

Answer

47,XXY

Question 8

A child presents with learning disabilities. On examination, horseshoe kidney and streak gonads are noted. What is your diagnosis?

Accepted Answer

Turner's syndrome

Answer

Klinefelter's syndrome

Answer

Noonan's syndrome

Answer

Fragile-X syndrome

Question 9

Hypothyroidism in infancy is characterized by which of the following findings, EXCEPT?

Accepted Answer

Hyperthermia

Answer

Constipation

Answer

Coarse facies

Answer

Wide open cranial sutures

Question 10

Which of the following is true in cretinism?

Accepted Answer

All of these

Answer

Prolonged physiological jaundice present

Answer

Common in iodine deficiency endemic areas

Answer

Delayed skeletal development

Endocrinology — MCQs

Endocrinology — MCQs

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