A 12-year-old girl is brought to the emergency department by her parents for assessment of confusion and rapid breathing. Three days ago the patient developed rhinorrhea, cough, and fever, which have since resolved. The parents say that over the past 48 hours the patient has had increased urination, abdominal pain, and fatigue progressing to somnolence. On arrival, the patient's temperature is 36.7 C (98 F), blood pressure is 110/70 mm Hg, pulse is 138/min, respirations are 36/min, and pulse oximetry is 99% on room air. On physical examination, she is ill-appearing with tachypnea, subcostal retractions, and dry mucous membranes. There is diffuse abdominal tenderness without rebound. Laboratory results are as follows: Which of the following is most likely decreased in this patient?

Question

A 12-year-old girl is brought to the emergency department by her parents for assessment of confusion and rapid breathing.  Three days ago the patient developed rhinorrhea, cough, and fever, which have since resolved.  The parents say that over the past 48 hours the patient has had increased urination, abdominal pain, and fatigue progressing to somnolence.  On arrival, the patient's temperature is 36.7 C (98 F), blood pressure is 110/70 mm Hg, pulse is 138/min, respirations are 36/min, and pulse oximetry is 99% on room air.  On physical examination, she is ill-appearing with tachypnea, subcostal retractions, and dry mucous membranes.  There is diffuse abdominal tenderness without rebound.  Laboratory results are as follows:  Which of the following is most likely decreased in this patient?

Quizplus · Accepted Answer

11ec25c8_d65c_ddf2_bc81_6f2f57114eae_MD0003_00 This patient with hyperglycemia and an anion gap metabolic acidosis has diabetic ketoacidosis (DKA), likely due to undiagnosed type 1 diabetes mellitus. Infection (eg, upper respiratory infection with fever, cough, and rhinorrhea in this patient) frequently precipitates DKA due to increased catecholamine, cortisol, and glucagon release. Presenting symptoms typically include polyuria, polydipsia, abdominal pain, and fatigue. On examination, patients are often dehydrated and breathing rapidly (ie, Kussmaul respirations) to compensate for the metabolic acidosis. During DKA, serum glucose exceeds the threshold for reabsorption by the kidneys, resulting in glucosuria and an osmotic diuresis. This diuresis is accompanied by a net renal loss of potassium with depletion of total body potassium stores. However, serum potassium levels may be normal (as seen in this patient) or elevated because acidemia and decreased insulin activity cause a potassium shift to the extracellular fluid compartment. potassium shift Treatment involves gradual fluid repletion and insulin administration. Insulin promotes potassium redistribution to the intracellular fluid compartment. Therefore, intravenous fluids are supplemented with potassium to prevent hypokalemia. (Choice A) Osmotic diuresis associated with DKA causes a reduction in effective circulating blood volume, which activates the renin-angiotensin-aldosterone system. Blood urea nitrogen and creatinine are often acutely elevated due to hypovolemia, as seen in this patient. (Choice B) DKA is characterized by an increase in circulating free fatty acids due to an underlying relative excess of glucagon to insulin and consequent increase in lipolysis. (Choice C) Hyperglycemia in DKA contributes not only to osmotic diuresis and hypovolemia but also to serum hyperosmolality. These effects generally promote pituitary vasopressin release. (Choice D) Hepatic gluconeogenesis increases in DKA due to increased circulating glucagon, catecholamines, and cortisol. (Choice F) Hyperglycemia in DKA causes an osmotic diuresis with increased urinary excretion of glucose, ketones, sodium, potassium, and phosphate. Educational objective: Diabetic ketoacidosis (DKA) presents with polyuria, abdominal pain, and fatigue and is often precipitated by infection. Laboratory results demonstrate hyperglycemia and an anion gap metabolic acidosis. DKA is characterized by an osmotic diuresis that reduces total body potassium even though serum potassium may be normal or elevated. References: Improving care for pediatric diabetic ketoacidosis. (http://www.ncbi.nlm.nih.gov/pubmed/25092935)

A 12-Year-Old Girl Is Brought to the Emergency Department by Her