Electrolytes & Acid-Base
Most common electrolyte abnormality seen in hospitalized children.
What is hyponatremia?
⭐ Always determine volume status in hyponatremia. SIADH typically presents with euvolemia and concentrated urine.
Most common cause of nephrotic syndrome in children.
What is minimal change disease?
⭐ Most children respond rapidly to corticosteroids without requiring renal biopsy.
Most common organism causing pediatric UTIs.
What is Escherichia coli?
⭐ E. coli accounts for most first febrile UTIs in otherwise healthy children.
Most common cause of acute kidney injury in hospitalized children.
What is prerenal azotemia?
⭐ Volume depletion from gastroenteritis remains a classic pediatric cause.
Most common cause of hypertension in adolescents.
What is primary (essential) hypertension?
⭐ Obesity is a major risk factor for adolescent primary hypertension.
A child with pyloric stenosis classically develops this acid-base abnormality.
What is hypochloremic hypokalemic metabolic alkalosis?
⭐ Persistent vomiting causes loss of hydrogen and chloride ions. Low urine chloride suggests volume depletion rather than renal losses.
Classic triad of nephrotic syndrome.
What is proteinuria, hypoalbuminemia, and edema?
⭐ Hyperlipidemia is another classic finding frequently tested on boards.
Preferred urine collection method in a non-toilet-trained febrile infant when culture is needed.
What is catheterized urine specimen?
⭐ Bagged specimens are acceptable only for screening urinalysis, not for culture confirmation.
Fractional excretion of sodium (FeNa) less than 1% suggests this type of AKI.
What is prerenal acute kidney injury?
⭐ In prerenal states, kidneys conserve sodium aggressively to maintain intravascular volume.
Most common cause of secondary hypertension in children.
What is renal disease?
⭐ Younger children with hypertension are more likely to have a secondary cause than adolescents.
This acid-base disorder is classically associated with diarrhea.
What is non-anion gap metabolic acidosis?
⭐ Diarrhea causes bicarbonate loss from the GI tract, leading to hyperchloremic metabolic acidosis.
Child presents with cola-colored urine, edema, hypertension, and low C3 two weeks after pharyngitis.
What is poststreptococcal glomerulonephritis?
⭐ Low complement levels usually normalize within 6–8 weeks in PSGN.
Imaging study recommended after a first febrile UTI in children 2–24 months.
What is renal and bladder ultrasound?
⭐ Routine VCUG is no longer recommended after the first uncomplicated febrile UTI.
Classic electrolyte abnormality seen in tumor lysis syndrome.
What is hyperkalemia?
⭐ Tumor lysis syndrome also causes hyperphosphatemia, hyperuricemia, and secondary hypocalcemia.
Gold standard test for confirming ambulatory hypertension.
What is ambulatory blood pressure monitoring (ABPM)?
⭐ ABPM helps distinguish white coat hypertension from persistent hypertension.
A neonate presents with severe dehydration, hyponatremia, hyperkalemia, and metabolic acidosis. Initial life-threatening diagnosis to rule out.
What is congenital adrenal hyperplasia?
⭐ Salt-wasting CAH is a neonatal emergency. Female infants may present with ambiguous genitalia, while males can initially appear normal.
This nephritic syndrome is associated with palpable purpura, abdominal pain, and arthritis.
What is IgA vasculitis (Henoch-Schönlein purpura)?
⭐ Renal involvement determines long-term prognosis in IgA vasculitis.
Most common congenital anomaly of the urinary tract detected prenatally.
What is hydronephrosis?
⭐ Many mild prenatal hydronephrosis cases resolve spontaneously after birth.
Child with polyuria, polydipsia, hypokalemia, metabolic alkalosis, and normal BP. Likely diagnosis.
What is Bartter syndrome?
⭐ Bartter syndrome mimics chronic loop diuretic use.
Child with hematuria, hearing loss, and ocular abnormalities.
What is Alport syndrome?
⭐ Alport syndrome results from mutations affecting type IV collagen.
Most common electrolyte abnormality associated with refeeding syndrome.
What is hypophosphatemia?
⭐ Refeeding syndrome occurs after rapid nutritional rehabilitation. Severe hypophosphatemia may lead to respiratory failure and arrhythmias.
A child develops recurrent episodes of gross hematuria within 1–2 days of an upper respiratory infection.
What is IgA nephropathy?
⭐ Unlike PSGN, IgA nephropathy usually presents with normal complement levels and hematuria occurring simultaneously with infection.
A child has recurrent febrile UTIs and renal scarring. Most likely underlying diagnosis.
What is vesicoureteral reflux?
⭐ High-grade reflux increases risk of renal scarring and hypertension later in life.
A child presents with nephrolithiasis, bone pain, constipation, and shortened QT interval on ECG. Electrolyte abnormality responsible.
What is hypercalcemia?
⭐ “Stones, bones, groans, and psychiatric overtones” is the classic hypercalcemia presentation tested on boards.
This syndrome presents with hemolytic anemia, thrombocytopenia, and acute kidney injury after bloody diarrhea.
What is hemolytic uremic syndrome (HUS)?
⭐ Avoid antibiotics and antimotility agents in STEC-associated HUS, as they may worsen toxin release.