USMLE Step 3 Quiz: Chronic Pediatric Conditions

What this quiz covers

This quiz focuses on Chronic Pediatric Conditions, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 3.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Child and adolescent mental health specialist for disordered eating and insulin omission (correct answer)
2. Orthopedic surgeon to evaluate for diabetic neuropathy causing appetite changes
3. Otolaryngologist to evaluate for sinus disease as the cause of hyperglycemia
4. Nephrologist to initiate dialysis to improve glycemic control

Explanation: This question tests the management of chronic pediatric conditions, specifically focusing on long-term care strategies and coordination with interdisciplinary teams. Chronic conditions like type 1 diabetes in teens can involve psychosocial issues like disordered eating, requiring mental health support. In this vignette, intentional insulin omission for weight control signals an eating disorder risk needing specialized intervention. Choice A is correct because consulting a mental health specialist addresses diabulimia per ADA recommendations. Choice B is incorrect because orthopedic evaluation isn't indicated without neuropathy evidence. To help students: Emphasize screening for psychosocial complications in diabetes. Practice identifying red flags for referral in adolescent care.

Question 2

1. Hemoglobin A1c.
2. Fasting serum lipid panel.
3. Sputum culture for non-tuberculous mycobacteria.
4. Oral glucose tolerance test. (correct answer)

Explanation: When you encounter a cystic fibrosis patient with declining weight despite adequate caloric intake combined with worsening pulmonary function, you should immediately consider cystic fibrosis-related diabetes (CFRD). This complication affects approximately 20% of adolescents and 40-50% of adults with CF, making it a critical screening priority. The oral glucose tolerance test (OGTT) is the gold standard for diagnosing CFRD because patients often have normal fasting glucose levels but demonstrate glucose intolerance after meals. CFRD develops due to progressive pancreatic destruction, leading to insulin deficiency. The combination of weight loss plateau and pulmonary decline strongly suggests this diagnosis, as hyperglycemia impairs immune function and promotes bacterial growth in airways. Looking at the incorrect options: A) Hemoglobin A1c can miss early CFRD because CF patients have altered red blood cell turnover and may not reach diagnostic thresholds despite having diabetes. B) A fasting lipid panel wouldn't explain the acute clinical changes described and isn't routinely indicated for CFRD screening. C) While non-tuberculous mycobacteria can cause pulmonary decline in CF, it wouldn't explain the weight plateau with adequate caloric intake, and this screening isn't typically prompted by these specific clinical changes. Remember that in CF patients, any unexplained decline in weight or pulmonary function should trigger CFRD screening with an OGTT, not just fasting glucose or A1c. Early detection and treatment of CFRD significantly improves both nutritional status and lung function outcomes.

Question 3

1. Progressive aortic stenosis.
2. Iron-deficiency anemia.
3. Recurrent endocarditis.
4. Chronic liver disease and fibrosis. (correct answer)

Explanation: When evaluating long-term complications in patients with Fontan circulation, focus on how the altered hemodynamics affect organ systems over time. The Fontan procedure creates a single-ventricle circulation where systemic venous return flows passively to the pulmonary arteries without a pumping chamber, resulting in chronically elevated central venous pressures. The correct answer is D because chronic liver disease and fibrosis represent the most significant long-term risk in Fontan patients. The persistently elevated central venous pressure (typically 12-15 mmHg compared to normal 2-8 mmHg) causes chronic hepatic congestion. This leads to progressive liver fibrosis, cirrhosis, and eventually hepatocellular carcinoma in some patients. This complication, known as Fontan-associated liver disease (FALD), affects nearly all long-term Fontan survivors and is now a leading cause of morbidity and mortality in this population. Option A is incorrect because progressive aortic stenosis isn't a characteristic complication of Fontan circulation. Option B is wrong because Fontan patients typically develop polycythemia (increased red blood cells) due to chronic mild hypoxemia, not iron-deficiency anemia. Option C is incorrect because while endocarditis risk exists in congenital heart disease, it's not the primary long-term concern specific to Fontan circulation compared to liver disease. Remember that Fontan physiology creates a high-pressure, low-flow venous system. When you see Fontan follow-up questions, immediately think about complications related to elevated venous pressures: liver disease, protein-losing enteropathy, arrhythmias, and thromboembolism. Liver disease is the most universal and progressive of these complications.

Question 4

1. Increase the evening dose of insulin glargine by 20%.
2. Refer him for evaluation for an insulin pump and continuous glucose monitor. (correct answer)
3. Add metformin to his current insulin regimen to improve insulin sensitivity.
4. Arrange a consultation with a dietitian to reinforce carbohydrate counting.

Explanation: This adolescent with long-standing type 1 diabetes has suboptimal glycemic control (HbA1c > 7.5%) and demonstrates difficulty with the complexities of a multiple daily injection regimen, particularly with postprandial glucose excursions. Referral for evaluation for an insulin pump and continuous glucose monitoring (CGM) is the most appropriate next step. This technology provides more physiologic insulin delivery, allows for real-time glucose data to guide therapy, and can improve glycemic control and quality of life, especially in adolescents struggling with regimen adherence and complexity.

Question 5

1. Initiation of hydroxyurea therapy. (correct answer)
2. Beginning a chronic simple blood transfusion program.
3. Administering the 23-valent pneumococcal polysaccharide vaccine.
4. Increasing the daily dose of folic acid supplementation.

Explanation: Hydroxyurea is a disease-modifying therapy that increases the production of fetal hemoglobin (HbF), which interferes with the polymerization of sickle hemoglobin. It is indicated for children with sickle cell anemia (HbSS) who experience frequent vaso-occlusive crises (typically defined as ≥3 moderate-to-severe crises in a 12-month period). This patient meets the criteria, and initiating hydroxyurea is the most effective intervention to reduce the frequency of both pain crises and acute chest syndrome.

Question 6

1. Prescribe a 14-day course of an oral antibiotic.
2. Initiate therapy with a CFTR modulator. (correct answer)
3. Increase the dose of her inhaled dornase alfa.
4. Start long-term therapy with azithromycin.

Explanation: This patient's gradual decline in lung function and nutritional status, despite standard therapies, suggests disease progression. For a patient who is homozygous for the F508del mutation, initiation of a highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulator (e.g., elexacaftor/tezacaftor/ivacaftor) is the most appropriate step. These agents target the underlying protein defect, leading to significant improvements in lung function, nutritional status, and quality of life.

Question 7

1. Obtain screening hip radiographs to evaluate for subluxation.
2. Discontinue physical therapy until his pain is better controlled.
3. Refer to a specialist for consideration of botulinum toxin injections. (correct answer)
4. Start a trial of a low-dose oral baclofen.

Explanation: The patient has focal spasticity in his lower extremities that is interfering with care and causing pain. Referral to a specialist (e.g., neurologist, physiatrist) for consideration of botulinum toxin injections is the most appropriate next step. Botulinum toxin is a first-line treatment for focal spasticity in cerebral palsy, as it can reduce muscle tone in targeted muscles, improve range of motion, and facilitate easier care and therapy. While oral baclofen can be used, it is more for generalized spasticity and has systemic side effects. Hip surveillance is important but does not address the acute problem of spasticity. Discontinuing therapy would be detrimental.

Question 8

1. Echocardiogram.
2. Cervical spine radiograph.
3. Thyroid-stimulating hormone (TSH) level. (correct answer)
4. Sleep study (polysomnography).

Explanation: Children with Down syndrome are at a significantly increased risk for autoimmune hypothyroidism. The AAP health supervision guidelines recommend screening with a TSH level at birth, 6 months, 12 months, and then annually throughout life. Therefore, obtaining a TSH level is the indicated screening test at this 4-year-old well-child visit. An echocardiogram should have been done in infancy. Cervical spine radiographs are only recommended for symptomatic children. A sleep study is recommended between ages 3 and 4, so it might be appropriate, but annual thyroid screening is a consistent requirement.

Question 9

1. Initiate therapy with an erythropoietin-stimulating agent.
2. Prescribe an active vitamin D analog such as calcitriol.
3. Start a non-calcium-based phosphate binder with meals. (correct answer)
4. Recommend supplementation with oral calcium carbonate.

Explanation: This patient has hyperphosphatemia and secondary hyperparathyroidism, characteristic of CKD-mineral and bone disorder. The cornerstone of initial management is controlling the serum phosphorus level. This is achieved through dietary phosphorus restriction and the use of phosphate binders taken with meals to prevent absorption of dietary phosphate. Starting a phosphate binder is the first and most critical step. Administering active vitamin D before controlling phosphorus can worsen hyperphosphatemia and lead to vascular calcification.

Question 10

1. He is at lifelong risk for right ventricular failure and arrhythmias. (correct answer)
2. He must take antibiotic prophylaxis before all future dental procedures.
3. He is now considered cured and will not require further cardiac follow-up.
4. He should immediately cease all athletic activities to avoid cardiac events.

Explanation: When you encounter questions about congenital heart disease in adults, focus on the long-term sequelae and ongoing management needs rather than immediate acute concerns. Tetralogy of Fallot repair, while life-saving, creates predictable long-term complications. The surgical correction typically involves patch repair of the ventricular septal defect and relief of pulmonary stenosis, but this often results in pulmonary regurgitation. Over decades, chronic volume overload from pulmonary regurgitation leads to progressive right ventricular dilation, dysfunction, and eventually heart failure. Additionally, surgical scarring and chronic hemodynamic changes create substrate for arrhythmias, particularly ventricular tachycardia and sudden cardiac death. This patient already shows early signs with moderate pulmonary regurgitation and mild RV dilation, making choice A correct. Choice B is incorrect because current guidelines don't recommend routine endocarditis prophylaxis for repaired Tetralogy of Fallot without residual defects. Choice C represents a dangerous misconception—congenital heart disease patients require lifelong cardiac surveillance even after "successful" repair, as complications typically emerge decades later. Choice D is overly restrictive; while competitive athletics may require evaluation, recreational sports are generally safe with normal RV function and no arrhythmias. Study tip: For USMLE Step 3, remember that "repaired" congenital heart disease doesn't mean "cured." These patients face predictable late complications based on their specific anatomy and repair type. Focus on the long-term hemodynamic consequences rather than immediate post-operative concerns.

Question 11

1. Juvenile myoclonic epilepsy is considered a lifelong condition with a very high relapse rate off medication. (correct answer)
2. Valproic acid has a high risk of teratogenicity if he were to father a child.
3. He must have a normal EEG before considering medication withdrawal.
4. The transition to college is often associated with significant sleep deprivation and stress.

Explanation: The most compelling reason is the natural history of the specific epilepsy syndrome. Juvenile myoclonic epilepsy (JME) is a genetic generalized epilepsy that is well-controlled with medication but has a very high relapse rate (75-95%) when medication is withdrawn, even after many years of seizure freedom. It is typically considered a lifelong condition requiring lifelong treatment. While the stress of college is a valid concern for any epilepsy patient (Distractor D), the fundamental biology of JME is the primary contraindication to stopping medication.

Question 12

1. Start daily low-dose aspirin.
2. Initiate hydroxyurea therapy.
3. Repeat the TCD in 3 months to monitor the trend.
4. Begin a chronic monthly blood transfusion program. (correct answer)

Explanation: When you encounter a sickle cell disease question involving transcranial Doppler (TCD) results, you're being tested on stroke prevention guidelines. TCD screening identifies children at high risk for stroke by measuring blood flow velocities in cerebral arteries. This patient has a TAMMV of 215 cm/sec, which falls in the abnormal range (≥200 cm/sec). The confirmatory repeat study confirms this elevated velocity, indicating significantly increased stroke risk. At this threshold, immediate intervention is required to prevent primary stroke. Answer D is correct because chronic transfusion therapy is the proven standard of care for children with sickle cell disease who have abnormal TCD velocities. Regular blood transfusions reduce the percentage of sickle hemoglobin (HbS) and maintain hemoglobin levels that decrease stroke risk. The STOP trial definitively demonstrated that chronic transfusions reduce stroke risk by approximately 92% in this population. Answer A is wrong because aspirin has no proven benefit for primary stroke prevention in sickle cell disease with abnormal TCD. Answer B is incorrect because while hydroxyurea is beneficial for reducing vaso-occlusive crises, it's not the first-line treatment for abnormal TCD velocities requiring immediate stroke prevention. The SWiTCH trial showed transfusions remain superior in this setting. Answer C is dangerous because waiting 3 months with confirmed abnormal velocities unnecessarily exposes the child to stroke risk when effective prevention is available. Remember: TCD velocity ≥200 cm/sec = immediate chronic transfusion therapy. This is a high-yield, evidence-based guideline you must know for Step 3.

Question 13

1. Providing a comprehensive medical summary for the new physician.
2. Arranging a joint appointment or a direct provider-to-provider phone call with the new adult endocrinologist. (correct answer)
3. Advising her to schedule her first adult appointment as soon as she arrives at college.
4. Reviewing sick-day rules and the importance of adherence one last time.

Explanation: The transition from pediatric to adult care is a high-risk period for patients with chronic illness, often associated with poor follow-up and worsening outcomes. For a high-risk patient like this, a structured handoff is crucial. A 'warm handoff,' such as a joint appointment or a direct conversation between the pediatric and adult providers, has been shown to improve transition success. It facilitates the transfer of complex medical information, establishes a relationship with the new provider, and helps alleviate patient anxiety, addressing the key barriers to a successful transition.

Question 14

1. Administer a correction bolus of insulin and encourage sips of a carbohydrate-containing beverage. (correct answer)
2. Continue the pump's basal rate, but do not give any correction boluses.
3. Disconnect the insulin pump and go to the emergency department immediately.
4. Withhold all insulin until he can tolerate a full meal to avoid hypoglycemia.

Explanation: When you encounter a diabetic child with illness who can't eat, remember that sick day management is crucial - the body's stress response during illness actually increases insulin needs, even when not eating. In this scenario, the child has hyperglycemia (290 mg/dL) and ketones despite not eating for 12 hours. This indicates inadequate insulin coverage. During illness, counter-regulatory hormones like cortisol and epinephrine increase glucose production and insulin resistance, explaining why blood sugar rises even without food intake. Choice A is correct because it addresses both immediate problems: the correction bolus treats the existing hyperglycemia and ketosis, while carbohydrate-containing fluids (like clear sodas or sports drinks) provide glucose to prevent hypoglycemia from the insulin while maintaining hydration. This prevents progression to diabetic ketoacidosis. Choice B fails to address the current hyperglycemia and ketones - basal insulin alone is insufficient when blood glucose is already elevated. Choice C is premature; while the situation needs monitoring, it's manageable at home initially with proper insulin adjustment. The child isn't in DKA yet (which would require IV insulin and fluids). Choice D reflects the dangerous misconception that you should withhold insulin when not eating - this can rapidly lead to DKA in type 1 diabetics, especially during illness. Key takeaway for Step 3: In pediatric type 1 diabetes sick day management, never stop insulin completely. The mantra is "insulin first, then carbohydrates" - treat the hyperglycemia while providing glucose sources to prevent hypoglycemia from the correction dose.

Question 15

1. Add an oral leukotriene receptor antagonist, such as montelukast.
2. Step up to a high-dose inhaled corticosteroid-LABA combination. (correct answer)
3. Initiate omalizumab injections every 2-4 weeks.
4. Continue the current regimen and schedule a follow-up in 3 months.

Explanation: According to GINA guidelines, this patient's asthma is not well-controlled. Features of poor control include using a short-acting beta-agonist more than twice a week and having two or more exacerbations requiring oral corticosteroids in the past year. Since he is already on a medium-dose ICS-LABA, the next appropriate step in management is to increase the controller therapy to a high-dose ICS-LABA combination. This is the preferred next step before considering add-on biologic therapies.

Question 16

1. Weight gain and cushingoid features.
2. Behavioral changes and irritability.
3. Posterior subcapsular cataracts.
4. Bone demineralization and vertebral fractures. (correct answer)

Explanation: When evaluating chronic corticosteroid side effects in pediatric patients with neuromuscular conditions like DMD, you need to consider both frequency and clinical severity. While steroids provide crucial functional benefits by slowing muscle deterioration, their long-term use creates significant management challenges. Bone demineralization and vertebral fractures (D) represent the most serious complication requiring intensive monitoring. Children with DMD already have reduced mobility, which decreases bone loading and contributes to osteoporosis. Chronic steroids dramatically accelerate this process by inhibiting osteoblast function and increasing bone resorption. The combination creates a perfect storm for pathological fractures, particularly vertebral compression fractures that can cause pain, deformity, and further functional decline. These complications require regular bone density monitoring, calcium/vitamin D supplementation, and sometimes bisphosphonate therapy. Weight gain and cushingoid features (A) are extremely common and cosmetically concerning but rarely life-threatening. Behavioral changes and irritability (B) are frequent early side effects that often improve with dose adjustments or alternative steroid regimens. Posterior subcapsular cataracts (C) do occur with chronic steroid use but develop slowly and can be surgically corrected when vision is significantly impaired. The key distinction is that while options A, B, and C represent manageable or reversible complications, vertebral fractures can cause permanent disability and pain in patients who already face progressive muscle weakness. Study tip: For USMLE Step 3, prioritize complications that cause irreversible harm or significantly impact quality of life when ranking adverse effects in chronic disease management scenarios.

Question 17

1. Development of refractory celiac disease.
2. Inadvertent and ongoing exposure to gluten. (correct answer)
3. Slow normalization of antibodies, which can take up to 3 years.
4. Co-existing autoimmune thyroiditis.

Explanation: In a patient with celiac disease who is clinically improving but has persistently elevated serology after a year on a gluten-free diet, the most common cause is ongoing, unintentional gluten ingestion. This can occur through cross-contamination in the kitchen, misreading food labels, or eating foods with hidden gluten. A detailed dietary review is necessary. While antibody levels can take 1-2 years to normalize in some, persistent elevation warrants investigation for non-adherence. Refractory disease is very rare in children.

Question 18

1. Empirically increase the frequency of adalimumab to weekly.
2. Schedule a colonoscopy to assess for disease activity.
3. Check serum C-reactive protein and fecal calprotectin levels. (correct answer)
4. Check adalimumab trough level and anti-drug antibody levels.

Explanation: When a patient with IBD on biologic therapy develops symptoms, it is crucial to first determine if there is objective evidence of inflammation. C-reactive protein (CRP) and fecal calprotectin are non-invasive markers of inflammation. If these are elevated, it confirms a disease flare and can guide further management decisions, such as drug level testing or endoscopy. If they are normal, other causes for the symptoms (e.g., irritable bowel syndrome, infection) should be considered. This is the best initial step before proceeding to more invasive or expensive tests, or empiric treatment changes.

Question 19

1. The medication can be stopped now, as she has been in remission for a full year.
2. She should be transitioned to a TNF-alpha inhibitor, which has fewer side effects.
3. Methotrexate should be continued for at least another 6 months before attempting to wean. (correct answer)
4. An MRI of her knees should be obtained to confirm remission before stopping medication.

Explanation: The management of JIA involves achieving and then maintaining remission. While a 12-month period of inactive disease is an excellent milestone, current consensus suggests continuing the disease-modifying antirheumatic drug (DMARD) for a period of sustained remission (often 6-12 months) before attempting a gradual taper. Discontinuing abruptly after achieving remission is associated with a high rate of disease flare. Therefore, continuing the medication for a further period before considering a trial of weaning is the most prudent approach.

Question 20

1. Allergic rhinitis with post-nasal drip.
2. Gastroesophageal reflux disease. (correct answer)
3. Vocal cord dysfunction.
4. Suboptimal inhaler technique.

Explanation: While allergic rhinitis and poor technique can contribute to asthma symptoms, the specific pattern of isolated nocturnal cough in the absence of other daytime symptoms is highly suggestive of gastroesophageal reflux disease (GERD). Acid reflux is worse in the supine position and can trigger a cough reflex or microaspiration, leading to nighttime respiratory symptoms. In a patient whose daytime asthma symptoms are otherwise well-controlled, GERD should be strongly considered as a contributing factor to persistent nocturnal cough.