A 1-month-old infant is evaluated for failure to thrive and is found to have a normal anion gap metabolic acidosis. The urine pH is 5. Bicarbonate therapy is initiated, but this leads to a significant increase in bicarbonate wasting in the urine, and the urine pH rises to 7.8. Which of the following is the most likely diagnosis?
A 6-month-old infant is brought to the emergency department with a 3-day history of watery diarrhea and poor oral intake. On examination, the infant is irritable, has sunken eyes, a dry mouth, and a delayed capillary refill of 3 seconds. The mother mentions the infant has had very few wet diapers. Which of the following is the most significant contributor to the infant’s total maintenance water needs?
A 15-year-old boy with a known renal transplant on tacrolimus presents with new-onset seizures. Labs show a serum magnesium of 0.6 mg/dL, potassium of 3.1 mEq/L, and calcium of 7.9 mg/dL. What is the most likely underlying cause of his hypocalcemia?
A 2-year-old is admitted with gastroenteritis and moderate dehydration. The initial labs show serum potassium of 2.8 mEq/L. The resident prepares to start intravenous fluids. At what point is it appropriate to add potassium to the IV fluids?
A 13-year-old female presents with persistent vomiting. Her labs show: K+ 3.0 mEq/L, HCO3 34 mEq/L. Her urine electrolytes show sodium of 30 mEq/L and chloride of 8 mEq/L. Why is the urinary chloride a more reliable indicator of her volume status than her urinary sodium?
A 9-year-old child is admitted for an appendectomy and is made nothing by mouth (NPO) overnight. In the morning, prior to surgery, a standard maintenance intravenous fluid is ordered. The primary purpose of including 5% dextrose in this fluid is to?
A 17-year-old marathon runner collapses near the finish line and is found to have a serum sodium of 122 mEq/L. His family reports he was drinking large volumes of water at every aid station. Which of the following factors, in addition to excessive water intake, is a key contributor to his severe hyponatremia?
A 16-year-old female with anorexia nervosa is admitted for refeeding. She is started on total parenteral nutrition. On day 3 of admission, she develops weakness and confusion. Which electrolyte abnormality is most likely responsible for these symptoms?
A 14-year-old with bulimia is brought in by her parents due to concerns about weakness and constipation. She has a metabolic alkalosis and severe hypokalemia. She denies laxative or diuretic abuse. A urine toxicology screen is negative. Which set of urine electrolytes would be most consistent with surreptitious vomiting as the cause of her condition?
A 12-year-old boy is brought to the ED after being found unresponsive. An arterial blood gas shows pH=7.15, pCO2=70 mmHg , HCO3=25 mEq/L. This acid-base disturbance is best described as?
