SPEX Pediatrics 4 — Questions and Answers
Question 1: A 2-year-old presents with bloody diarrhea, abdominal pain, and pallor. Labs show microangiopathic hemolytic anemia, thrombocytopenia, and elevated creatinine. Which organism most commonly causes this condition?
- Salmonella typhi
- Shiga toxin-producing E. coli (STEC O157:H7) (Correct answer)
- Campylobacter jejuni
- Clostridium difficile
Correct answer: Shiga toxin-producing E. coli (STEC O157:H7)
Hemolytic uremic syndrome (HUS) is most commonly caused by Shiga toxin-producing E. coli, especially O157:H7, often acquired from undercooked beef.
Question 2: Which of the following is the most common cause of nephrotic syndrome in children aged 1–8 years?
- Focal segmental glomerulosclerosis
- Membranous nephropathy
- Minimal change disease (Correct answer)
- IgA nephropathy
Correct answer: Minimal change disease
Minimal change disease is responsible for approximately 80% of nephrotic syndrome cases in children and typically responds well to steroids.
Question 3: A newborn has failure to pass meconium within 48 hours of birth. Rectal exam produces explosive passage of stool and gas. What is the most likely diagnosis?
- Meconium ileus
- Imperforate anus
- Hirschsprung disease (Correct answer)
- Duodenal atresia
Correct answer: Hirschsprung disease
Hirschsprung disease is caused by absence of ganglion cells in the distal colon; rectal decompression produces explosive stool release due to proximal distention.
Question 4: A 4-year-old presents with periorbital edema worse in the morning, frothy urine, and no hematuria. Urinalysis shows 4+ protein. What is the best initial treatment?
- ACE inhibitor
- Oral prednisone (Correct answer)
- Cyclophosphamide
- Dietary sodium restriction alone
Correct answer: Oral prednisone
First-line treatment for childhood nephrotic syndrome (minimal change disease) is oral corticosteroids, typically prednisone.
Question 5: Which developmental screening tool is recommended by the AAP for all children at 18 and 24 months specifically to screen for autism spectrum disorder?
- Denver Developmental Screening Test II
- Ages and Stages Questionnaire (ASQ)
- Modified Checklist for Autism in Toddlers (M-CHAT) (Correct answer)
- Bayley Scales of Infant Development
Correct answer: Modified Checklist for Autism in Toddlers (M-CHAT)
The M-CHAT is the AAP-recommended autism-specific screening tool used at 18 and 24-month well-child visits.
Question 6: A 10-year-old is brought in for school difficulty and is found to have a blood lead level of 25 µg/dL. What is the appropriate next step?
- Reassure parents — this level requires no action
- Environmental investigation and lead source removal (Correct answer)
- Immediately start chelation therapy with DMSA
- Refer for bone marrow biopsy
Correct answer: Environmental investigation and lead source removal
At blood lead levels of 5–44 µg/dL, the priority is identifying and eliminating the lead source through environmental investigation.
Question 7: A 7-year-old is diagnosed with attention deficit hyperactivity disorder (ADHD). According to AAP guidelines, what is the first-line treatment for school-age children?
- Behavioral therapy alone
- FDA-approved stimulant medication plus behavioral therapy (Correct answer)
- Non-stimulant medication alone
- Dietary modification and neurofeedback
Correct answer: FDA-approved stimulant medication plus behavioral therapy
AAP guidelines recommend stimulant medication (methylphenidate or amphetamine) combined with behavioral therapy as first-line treatment for school-age children with ADHD.
SPEX Pediatrics 4
A 2-year-old presents with bloody diarrhea, abdominal pain, and pallor.
Labs show microangiopathic hemolytic anemia, thrombocytopenia, and elevated creatinine.
Which organism most commonly causes this condition?