Pediatric Endocrinology (Thyroid, CAH, Diabetes, Puberty Disorders) MCQs

Pediatrics · 46 free questions with answers & explanations.

1. A neonate has ambiguous genitalia with virilized female external genitalia (clitoromegaly, labial fusion). On day 10, the baby develops hyponatremia (Na 120 mEq/L), hyperkalemia, and hypotension. Serum 17-OH progesterone is markedly elevated. What is the MOST likely diagnosis?
2. An 8-year-old girl develops breast buds, pubic hair, and axillary hair. Her bone age is 11 years and GnRH stimulation test shows a pubertal LH response. What is the TREATMENT OF CHOICE?
3. A 5-day-old neonate born of consanguineous parents presents with ambiguous genitalia in a 46,XX infant. Electrolytes show sodium 118 mEq/L and potassium 7.2 mEq/L. Serum 17-hydroxyprogesterone is markedly elevated at 50,000 ng/dL. Which enzyme deficiency is MOST likely, and which is the MOST dangerous immediate complication without treatment?
4. A 12-year-old girl presents with breast development (Tanner stage 3), pubic and axillary hair, and regular menstruation starting at age 10. Height is on the 90th centile currently but predicted adult height is significantly below her mid-parental height. GnRH stimulation test shows LH peak >10 IU/L. The MOST appropriate treatment to optimize final adult height is:
5. A 2-week-old female neonate presents with ambiguous genitalia: clitoral hypertrophy, posterior labial fusion, and a single urogenital sinus opening. She is found to have a 46,XX karyotype. Serum 17-OH progesterone is markedly elevated at 40,000 ng/dL. Which of the following enzyme deficiency accounts for the MAJORITY of congenital adrenal hyperplasia cases and this clinical presentation?
6. A 7-year-old girl is brought with rapid breast development, pubic hair appearance, and a recent growth spurt. Bone age is 11 years. LH response to GnRH stimulation test is pubertal (LH >5 IU/L). Brain MRI shows a small hypothalamic hamartoma. Which of the following is the most appropriate management?
7. A 10-day-old female neonate is found on national newborn screening to have TSH 180 mIU/L and free T4 of 0.4 ng/dL. She is clinically asymptomatic with no goitre. The most appropriate management is:
8. An 8-year-old girl presents with pubic hair (Tanner stage 2), axillary hair, but no breast development and no clitoromegaly. She has advanced bone age. 17-hydroxyprogesterone is markedly elevated. The most common enzyme deficiency responsible for this presentation is:
9. A 13-year-old girl presents with primary amenorrhoea, absence of breast development, and short stature. FSH is markedly elevated (85 mIU/mL), LH is elevated (42 mIU/mL), and oestradiol is undetectable. Karyotype is 45,X. What additional cardiac evaluation is mandatory before starting oestrogen replacement?
10. A 10-day-old girl from a rural area presents with prolonged jaundice, constipation, umbilical hernia, large tongue, hoarse cry, and hypotonia. TSH is 150 mIU/L and free T4 is undetectable. What is the MOST critical reason for URGENCY in initiating treatment?
11. A 46,XX infant presents with ambiguous genitalia at birth. Serum 17-hydroxyprogesterone is markedly elevated (>10,000 ng/dL). The serum sodium is 120 mEq/L, potassium is 6.8 mEq/L, and there is metabolic acidosis. Which enzyme is MOST likely deficient, and what is the IMMEDIATE priority?
12. An 8-year-old girl develops breast budding (Tanner stage 2) and pubic hair. Her bone age is 11 years. GnRH stimulation test shows pubertal LH/FSH response (LH/FSH > 1 post-stimulation). Pelvic ultrasound shows multicystic ovaries. What is the diagnosis and the PREFERRED treatment?
13. A 15-day-old neonate is found on newborn screening to have elevated TSH (85 mIU/L) and low T4. The neonate appears comfortable but has prolonged jaundice, large fontanelle, constipation, and umbilical hernia. Treatment with levothyroxine is initiated. What is the TARGET TSH range and T4 range during the first 1–3 years of life in treated congenital hypothyroidism?
14. A 2-week-old female neonate born to a consanguineous couple presents with salt-wasting crisis: vomiting, poor feeding, hypotension, hyponatremia (Na 118 mEq/L), hyperkalemia (K 7.2 mEq/L), and metabolic acidosis. Genitalia show clitoromegaly and labial fusion. 17-OHP is markedly elevated (>100 nmol/L). Which enzyme deficiency is responsible and what is its mode of inheritance?
15. A 7-year-old girl is brought with pubic hair development (Tanner stage 2) for 3 months. Breast development is absent. Bone age is 8 years. Serum DHEAS is elevated; LH/FSH are prepubertal. She is otherwise healthy with normal height velocity. The MOST likely diagnosis is:
16. A 14-year-old boy is referred for tall stature, long limbs, gynaecomastia, sparse pubic hair, small firm testes (2 mL volume), and azoospermia. His IQ is normal. Karyotype is 47,XXY. Testosterone is low, FSH and LH are markedly elevated. Which statement about the pathophysiology is CORRECT?
17. A 7-year-old girl presents with breast development (Tanner stage 2) and pubic hair, with advanced bone age (10 years). GnRH stimulation test shows LH >5 IU/L (pubertal response). Brain MRI is normal. She is diagnosed with idiopathic central precocious puberty. The MOST appropriate pharmacological treatment and its mechanism are:
18. A 10-year-old child is admitted with diabetic ketoacidosis (DKA). Blood glucose 450 mg/dL, pH 7.10, HCO3 8 mEq/L, Na 128 mEq/L, effective osmolality 310 mOsm/kg. IV fluids and insulin infusion are commenced. Six hours later, the child develops sudden headache, vomiting, altered consciousness, and anisocoria. The MOST likely complication and its primary pathophysiology are:
19. A 7-year-old girl is brought with breast development for the last 8 months. There is Tanner stage 3 breast development but no pubic or axillary hair, and no acceleration of growth. Bone age is 7.5 years. LH and FSH are prepubertal after GnRH stimulation. What is the MOST likely diagnosis?
20. A 13-year-old boy has not started puberty. Testicular volume is 2 mL bilaterally, no pubic hair, height 148 cm (below 3rd centile), height velocity 4 cm/year. His father started puberty at 16 years. LH and FSH are both low. Bone age is 11 years. Olfactory testing is normal. What is the MOST likely diagnosis and appropriate initial management?
21. A 10-day-old female neonate undergoes newborn screening which shows elevated 17-hydroxyprogesterone (17-OHP). She has ambiguous genitalia with clitoromegaly and posterior labial fusion. Electrolytes show Na 128 mEq/L, K 6.2 mEq/L. The enzyme deficiency most likely responsible and the reason for salt-wasting is:
22. An 8-year-old girl presents with breast development (Tanner stage 2) for the past 3 months. No pubic hair. Height velocity is increased at 7 cm/year. Bone age is 11 years. GnRH stimulation test shows LH peak >5 IU/L with LH:FSH ratio >1. The diagnosis is central precocious puberty (CPP). The RECOMMENDED treatment to preserve adult height in this child is:
23. A 13-year-old boy presenting with type 1 diabetes mellitus develops an acute illness with vomiting. Blood glucose is 380 mg/dL. Blood gas: pH 7.18, HCO3 10 mEq/L. Serum sodium is 130 mEq/L. During DKA fluid resuscitation, the most dreaded and potentially fatal complication to monitor for is:
24. A 2-year-old boy is found on screening to have elevated TSH (85 mIU/L) and very low free T4. He was born post-term with prolonged neonatal jaundice. On examination he has macroglossia, umbilical hernia, coarse facies, and hypotonia. The most important reason for urgency in treatment initiation is:
25. A 2-week-old female neonate presents with ambiguous genitalia, hyperpigmentation, and on day 7 develops vomiting, poor feeding, and hyponatremia (Na 122 mEq/L) with hyperkalemia (K 6.8 mEq/L). 17-OH progesterone levels are markedly elevated (>300 nmol/L). Which enzyme deficiency is MOST LIKELY and what is the biochemical mechanism for the salt-wasting crisis?
26. A 7-year-old girl develops breast buds with Tanner stage 2 breast development, pubic hair, and menarche at 7.5 years. Bone age is 12 years. GnRH stimulation test shows pubertal LH and FSH response. Which management is MOST APPROPRIATE?
27. A 12-year-old obese boy is found to have fasting plasma glucose of 148 mg/dL and HbA1c of 8.4%. He has acanthosis nigricans and a family history of type 2 diabetes in both parents. C-peptide levels are elevated. Which of the following is TRUE regarding the use of metformin in pediatric type 2 diabetes?
28. A 3-week-old neonate has prolonged jaundice, hypotonia, coarse facies, large fontanelle, umbilical hernia, macroglossia, and constipation. TSH on newborn screening is 180 mIU/L (normal <10). What is the most common cause of congenital hypothyroidism?
29. A 5-day-old female neonate presents with ambiguous genitalia, virilisation, hyperkalemia (K 6.9 mEq/L), hyponatremia (Na 122 mEq/L), and hypoglycaemia. 17-OHP is markedly elevated at 6800 ng/dL (normal <100). Which enzyme deficiency is responsible?
30. A 3-day-old neonate is identified on newborn screening with TSH >50 mU/L and low free T4. She appears well with mild hypotonia. The etiological classification of neonatal hypothyroidism and the MOST common cause is:
31. A 2-week-old female neonate has ambiguous genitalia: clitoral enlargement and labial fusion. Serum 17-hydroxyprogesterone (17-OHP) is markedly elevated at 28,000 ng/dL (normal <100). Electrolytes show Na 128, K 6.5 mEq/L. The enzyme deficiency responsible for this life-threatening form of CAH is:
32. A female neonate presents with ambiguous genitalia, hyperpigmentation, hyponatraemia (Na 126 mEq/L), hyperkalaemia (K 6.8 mEq/L), and low blood pressure on day 5 of life. Serum 17-hydroxyprogesterone is markedly elevated. Which enzyme deficiency is responsible for the MOST common form of congenital adrenal hyperplasia?
33. A 13-year-old boy with type 1 diabetes presents with polyuria, polydipsia, and blood glucose of 410 mg/dL. C-peptide is undetectable. Anti-GAD65 antibodies are positive. He develops DKA. Which pathophysiological mechanism is responsible for the high anion gap metabolic acidosis in this child?
34. A female neonate has ambiguous genitalia (clitoromegaly, posterior labial fusion, urogenital sinus), virilization, and bilateral inguinal masses. Electrolytes show Na+ 124 mEq/L, K+ 6.8 mEq/L, and plasma 17-OH progesterone is markedly elevated (>10,000 ng/dL). Which enzyme deficiency is responsible and which steroid pathway is BLOCKED?
35. A 10-year-old girl is diagnosed with type 1 diabetes mellitus. She is started on basal-bolus insulin. Three months later, she is apparently needing significantly less insulin and maintaining good control. Which physiological explanation BEST describes this phenomenon?
36. A 5-day-old neonate is identified on newborn screen with elevated 17-hydroxyprogesterone. She presents with vomiting, poor feeding, weight loss, hypoglycemia, hyponatremia (Na 125 mEq/L), and hyperkalemia (K 6.8 mEq/L). Which enzyme deficiency is most likely?
37. A 10-year-old girl presents with increasing fatigue, weight gain, cold intolerance, constipation, dry skin, and a diffusely enlarged, non-tender, firm goiter with a 'pebbly' surface. TSH is 18 mIU/L, free T4 is 0.6 ng/dL. Which antibody is most likely elevated and confirms the diagnosis?
38. A 10-day-old neonate presents with prolonged jaundice, poor feeding, constipation, macroglossia, an umbilical hernia, and a large anterior fontanelle. Serum TSH is 85 mIU/L (normal <10) and free T4 is 0.4 ng/dL (low). What is the MOST URGENT treatment?
39. A female neonate is born with ambiguous genitalia. Clitoral enlargement and labioscrotal fusion are noted. Serum electrolytes show Na 128 mEq/L, K 6.8 mEq/L, and glucose is 45 mg/dL. The 17-hydroxyprogesterone level is markedly elevated. The ENZYME deficiency MOST likely responsible is:
40. A 12-year-old boy is newly diagnosed with type 1 diabetes (HbA1c 11.2%, random glucose 380 mg/dL, ketones trace). He is alert and not in DKA. What is the MOST appropriate initial management?
41. A female neonate is found to have ambiguous genitalia at birth: clitoromegaly, posterior labial fusion with a rugated appearance, and a blind vaginal pouch. Karyotype is 46, XX. Serum 17-hydroxyprogesterone is markedly elevated at 48 hours. What is the MOST specific enzyme defect and the immediate life-threatening concern?
42. A 10-year-old child with type 1 diabetes mellitus has HbA1c consistently above 9% despite multiple daily injections. His fasting glucose in the morning is persistently high. His continuous glucose monitoring (CGM) data shows glucose values rising between 3–8 AM without a preceding nocturnal hypoglycemia. What is the most likely cause and management?
43. A 3-week-old neonate is noted to have prolonged jaundice, constipation, large tongue, umbilical hernia, and poor feeding. TSH from newborn screening is 285 mIU/L (normal <20). Free T4 is undetectable. The most common etiology and the critical parameter for determining outcome is:
44. A female neonate presents with virilized external genitalia (Prader stage III) at birth. Serum 17-hydroxyprogesterone is markedly elevated. Cortisol is low. Aldosterone is undetectable and renin is high. The enzyme deficient in this most common form of congenital adrenal hyperplasia is:
45. A term neonate develops ambiguous genitalia (virilized female, 46,XX karyotype), hyponatremia (Na+ 120 mEq/L) and hyperkalemia (K+ 7.2 mEq/L) with hypotension on day 7 of life. 17-hydroxyprogesterone is grossly elevated. The enzyme deficient in the most common form of this disorder is:
46. A 12-year-old girl with type 1 diabetes, well-controlled on insulin, develops diffuse thyroid enlargement. TSH is elevated at 18 mIU/L, free T4 is low-normal, and thyroid peroxidase antibodies are strongly positive. The diagnosis and management is: