Pediatrics

An 18-month-old toddler is transferred to a tertiary care center for progressive unsteadiness, refusal to walk, and unusual eye movements that began two weeks ago. The patient had previously achieved independent ambulation at 13 months. Her parents note she has become exceptionally cranky and exhibits sudden jerky body movements. They also mention they are worried because she speaks about 15 individual words but has not yet started combining them into two-word phrases. She is afebrile, and her vital signs are age-appropriate. Neurologic evaluation reveals chaotic, multi-directional, rapid conjugate ocular movements occurring without a distinct slow phase. She also demonstrates brief, involuntary, shock-like muscle spasms in her proximal limbs and trunk. When seated, she has marked truncal titubation. She was started on intravenous vancomycin and ceftriaxone two days ago; however, blood and cerebrospinal fluid cultures drawn at that time remain sterile, and she has no signs of infection. The medical team plans to initiate high-dose intravenous corticosteroids and rituximab later today.

Which of the following diagnostic or management steps are indicated for this patient? (Select exactly 2 options)

A 6-year-old boy is brought to the emergency department by his parents due to severe, intermittent abdominal pain that began 12 hours ago. During the episodes, the patient cries out and pulls his knees to his chest. He has also had two episodes of non-bilious vomiting. Over the past week, the parents noted a low-grade fever, bilateral ankle swelling, and a bumpy, reddish-purple rash on his buttocks and posterior thighs that does not disappear when pressure is applied. Today, he passed a stool containing dark red blood and mucus. Vital signs are temperature 37.8°C (100.0°F), heart rate 118/min, and blood pressure 105/65 mmHg. Abdominal examination reveals diffuse tenderness and a palpable, sausage-shaped fullness in the right middle quadrant. A point-of-care abdominal ultrasound shows a multi-layered, alternating echogenic and hypoechoic concentric ring mass in the right abdomen. Which of the following best describes the underlying pathogenesis of the focal abnormality that directly triggered this patient's acute gastrointestinal complication?

A 13-year-old obese boy presents to the emergency department with a 3-week history of vague right thigh and knee pain. Today, the pain acutely worsened after he slipped and fell on a wet floor, and he is now completely unable to bear weight on his right leg. On physical examination, the right leg is held in external rotation. When the examiner passively flexes the right hip, the leg obligately externally rotates. Arrange the following steps in the optimal chronological sequence for the management of this patient.

An $8$-month-old boy is evaluated in the pediatric emergency department for irritability, poor feeding, and passing copious amounts of dilute-appearing urine over the past three days. His parents report that he frequently demands breast milk or water but often vomits shortly afterward. His birth and prenatal history were unremarkable. He is currently at the $5$ th percentile for weight and $25$ th percentile for length, having dropped from the $50$ th percentile for weight at his $4$-month visit. Temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $85/50 \text{ mm Hg}$, and pulse is $160/\text{min}$. Physical examination shows dry mucous membranes, a sunken anterior fontanelle, and poor skin turgor. Initial laboratory studies show:

Serum sodium: $154 \text{ mEq/L}$
Serum potassium: $4.0 \text{ mEq/L}$
Serum osmolality: $318 \text{ mOsm/kg H}_2\text{O}$
Urine osmolality: $95 \text{ mOsm/kg H}_2\text{O}$

The patient is admitted, and subcutaneous desmopressin is administered. Two hours later, a repeat urine osmolality is $105 \text{ mOsm/kg H}_2\text{O}$. Which of the following is the most appropriate long-term pharmacotherapy to reduce polyuria in this patient?

An infant, aged 4 months, is brought to the emergency department by her parents due to a three-day history of a progressively weakened cry and diminished spontaneous movements. The parents note she has been feeding poorly and has not passed a bowel movement for the last five days. The infant was born at term without complications and had been meeting early developmental milestones appropriately. The family recently relocated to a rural agricultural community and is renovating an old farmhouse, exposing the home to significant environmental dust. Vital signs are within normal limits. Physical examination reveals a lethargic infant with profound generalized hypotonia and severe head lag. Bilateral ptosis, sluggishly reactive pupils, and a markedly weak gag reflex are present. Deep tendon reflexes are diffusely diminished. Which of the following is the most appropriate next step in management?

A $9$-month-old boy is brought to the clinic for a routine evaluation. His parents are concerned because he is not yet sitting without support and seems less active than his older siblings were at this age. He was born at $40$ weeks gestation following an uncomplicated pregnancy. The state newborn screening, which utilizes a primary thyroid-stimulating hormone (TSH) assay, was reported as normal. Over the last six months, his length has fallen from the $50$ th to the $5$ th percentile, and his weight has fallen from the $40$ th to the $10$ th percentile. On physical examination, the infant has generalized hypotonia, a prominent forehead, and a remarkably small phallus.

Laboratory testing reveals the following:

Which of the following is the most likely underlying cause of this patient's clinical and laboratory findings?

A $3$-year-old unimmunized boy is brought to the emergency department by his parents due to a rapidly progressive fever, severe sore throat, and difficulty breathing that started $4$ hours ago. On examination, the patient is sitting up, leaning forward with his hands on his knees, and keeping his neck hyperextended. He is drooling continuously and has audible inspiratory stridor. He appears highly anxious and toxic. His temperature is $39.5^\circ\text{C}$ ($103.1^\circ\text{F}$), heart rate is $150/\text{min}$, and respiratory rate is $40/\text{min}$. Oxygen saturation is $92\%$ on room air. Based on the most likely diagnosis, arrange the following management steps in the most appropriate chronological sequence to safely evaluate and treat this patient.

A 7-year-old boy is brought to the pediatrician by his parents because of declining academic performance. His teacher reports that he frequently "stares off into space" during class for 10 to 15 seconds at a time. During these episodes, the boy does not respond to his name and exhibits subtle lip smacking. Immediately after the episode ends, he resumes his schoolwork without any confusion or lethargy. His physical and neurological examinations are completely normal. Having the patient hyperventilate in the office for two minutes reproduces one of these episodes. Which of the following is the most likely diagnosis?

A 6-month-old girl of Ashkenazi Jewish descent is brought to the pediatrician due to parental concerns about her development. The parents report that she was previously able to roll over and reach for objects, but she has lost these abilities over the past month. Physical examination reveals hypotonia, a protuberant abdomen with palpable hepatosplenomegaly, and decreased deep tendon reflexes. Funduscopic examination demonstrates a bilateral cherry-red spot on the macula. Which of the following enzymes is most likely deficient in this patient?

During a mid-winter pediatric clinic visit, a couple seeks medical advice for their 8-month-old son. For the past four days, the infant has experienced copious clear rhinorrhea and a low-grade fever. Last night, the parents noticed he was breathing more rapidly than usual and making a whistling sound when exhaling. He is feeding slightly less than normal but continues to produce a normal amount of wet diapers. The infant was born at 36 weeks gestation. His 4-year-old sister recently had a mild upper respiratory tract infection. Vital signs show a temperature of 37.6°C (99.7°F), respiratory rate of 52/min, and oxygen saturation of 94% on room air. Physical examination reveals an alert infant with mild intercostal retractions, profuse nasal secretions, and bilateral expiratory wheezes without crackles. Which of the following is the most appropriate management for this patient?

A 9-day-old female infant is admitted to the neonatal intensive care unit for profound lethargy, tachypnea, and recurrent vomiting. She was born at full term via uncomplicated delivery and appeared well until two days ago when breastfeeding was supplemented with a cow's milk-based formula. On examination, the infant is unresponsive to tactile stimuli and exhibits generalized hypotonia.

Laboratory studies are as follows:

Restriction of which of the following groups of amino acids is most critical for the long-term management of this patient's underlying condition?

A 7-year-old boy with newly diagnosed Burkitt lymphoma is started on induction chemotherapy. Within 24 hours, he develops lethargy, nausea, and decreased urine output. Laboratory studies show hyperkalemia, hyperphosphatemia, hypocalcemia, and elevated serum uric acid levels. Arrange the following pathophysiologic events in the correct chronological order leading to this patient's acute kidney injury.

An $11$-year-old girl is brought to the outpatient pediatric clinic by her father due to an $8$-week history of right-sided distal thigh and knee pain. The pain is described as a dull ache that worsens with physical activity, particularly after her dance classes, and improves with rest. She has not experienced any preceding trauma, fever, chills, or weight loss. Her past medical history is unremarkable, and she takes no medications. Vital signs show a temperature of $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), heart rate of $78/\text{min}$, and blood pressure of $112/68 \text{ mm Hg}$. Her body mass index (BMI) is $28.5 \text{ kg/m}^2$ (above the $95^{\text{th}}$ percentile for age). Physical examination reveals a well-appearing girl walking with an antalgic gait. Inspection of the right knee shows no erythema, effusion, or localized tenderness over the tibial tuberosity or joint line. Ligamentous and meniscal testing of the knee is normal. When the patient is placed in the supine position and the right hip is passively flexed, the thigh deviates into obligatory external rotation. Internal rotation of the right hip is limited and elicits discomfort. Laboratory studies reveal a leukocyte count of $7,200/\text{mm}^3$, an erythrocyte sedimentation rate of $8 \text{ mm/h}$, and a C-reactive protein level of $0.3 \text{ mg/dL}$. Which of the following is the most appropriate next step in management?

An urgent care physician evaluates a 6-month-old male infant with a 3-day history of nasal congestion, low-grade fever, and increasingly labored breathing. The infant was born prematurely at 34 weeks gestation. Vital signs show a temperature of 38.0°C (100.4°F), heart rate of 158/min, respiratory rate of 64/min, and oxygen saturation of 88% on room air. Physical examination demonstrates an agitated infant with prominent subcostal retractions, nasal flaring, and head bobbing. Lung auscultation reveals prolonged expiration, diffuse bilateral wheezing, and scattered coarse crackles. There are no focal areas of decreased breath sounds. Which of the following are appropriate interventions in the initial management of this patient? (Select all that apply)

A 6-month-old female infant is brought to the clinic for a routine well-child examination. The parents have no concerns and report that the infant is feeding well, babbling, and rolling over from front to back. She was born at 39 weeks gestation via uncomplicated spontaneous vaginal delivery to a 28-year-old primigravid woman. Family history is significant for a maternal aunt who required treatment for a hip condition during infancy. On physical examination, the infant's vital signs are within normal limits. She is alert, active, and interactive. Examination of the lower extremities reveals asymmetric thigh and gluteal skin folds. When the infant is placed in the supine position with both hips and knees flexed and feet resting flat on the examining table, the right knee rests visibly lower than the left knee. The Ortolani and Barlow maneuvers do not elicit any clunk or instability. Which of the following is the most appropriate next step in management?

Paramedics transport a $6$-month-old male infant to the acute care pediatric triage unit after his parents reported sudden unresponsiveness following three days of nasal congestion and a mild cough. According to the mother, the infant was born prematurely at $34$ weeks gestation and had been struggling to feed for the past $24$ hours. Upon arrival at the facility, his temperature is $37.8^\circ\text{C}$ ($100.0^\circ\text{F}$), pulse is $175/\text{min}$, and respirations are recorded at $65/\text{min}$. Pulse oximetry shows an oxygen saturation of $86\%$ on room air.

Initial physical assessment reveals an agitated infant demonstrating profound subcostal and intercostal retractions, head bobbing, and pronounced nasal flaring. Diffuse expiratory wheezing with scattered crackles is heard throughout all lung fields. The clinical team immediately initiates heated, humidified high-flow oxygen therapy.

Thirty minutes into the intervention, the infant's clinical status changes: he becomes flaccid and difficult to arouse. The respiratory rate drops to $24/\text{min}$, and previously noted wheezing is now replaced by severely diminished breath sounds bilaterally. A capillary blood gas is obtained while on high-flow oxygen, revealing:

What is the most appropriate next step in the management of this patient?

Match each classic pediatric clinical presentation with the corresponding defective enzyme.

An $8$-week-old female infant presents to the urgent care clinic with fussiness and refusal to feed for the past four hours. The infant is alert and responsive. Vital signs include a heart rate of $270\text{ /min}$, respiratory rate of $50\text{ /min}$, and blood pressure of $82/48\text{ mmHg}$. Peripheral pulses are robust, capillary refill is under $2\text{ seconds}$, and extremities are warm. A 12-lead electrocardiogram shows a regular, narrow-complex tachycardia with absent P waves and constant R-R intervals. A peripheral intravenous line is already in place. Arrange the following acute management steps in the correct progressive order, from the initial non-pharmacologic approach to subsequent therapies if the arrhythmia persists.

A 4-month-old boy is brought to the emergency department by his parents due to a 3-day history of progressively worsening difficulty feeding and a 'weak' cry. The parents note that he has not had a bowel movement in 5 days. He was born at 39 weeks gestation without complications. He is exclusively breastfed but was recently given a pacifier dipped in honey to soothe him. Vital signs are within normal limits. Physical examination reveals a lethargic infant with bilateral ptosis, sluggish pupillary light reflexes, and pooling of oral secretions. When pulled by the arms to a sitting position, he exhibits pronounced head lag. Deep tendon reflexes are trace diffusely. Which of the following is the most appropriate next step in management?

A $12$-year-old adolescent is brought to the emergency triage in a lethargic state. The parents note a three-week history of unquenchable thirst, frequent nighttime urination, and a $4\text{-kg}$ weight loss. Clinical examination reveals deep, rapid respirations and a heart rate of $135\text{/min}$. Point-of-care testing shows a capillary blood glucose of $580 \text{ mg/dL}$. A venous blood gas demonstrates a pH of $7.08$ and a calculated anion gap of $24 \text{ mEq/L}$. The patient is diagnosed with severe diabetic ketoacidosis (DKA). Arrange the following therapeutic interventions in the appropriate chronological order, reflecting the standard pediatric endocrine protocol to safely correct the metabolic derangement while minimizing the risk of cerebral edema.