A 20-year-old woman comes to the emergency department with lethargy, abdominal pain, and nausea. She has had polyuria and excessive thirst for one day. She also complains of dysuria and chills over the last few days but did not seek medical care until today. Physical examination shows tachycardia and dry mucous membranes. Laboratory results are as follows: Which of the following electrolyte findings would most likely be seen in this patient?

Question

A 20-year-old woman comes to the emergency department with lethargy, abdominal pain, and nausea. She has had polyuria and excessive thirst for one day. She also complains of dysuria and chills over the last few days but did not seek medical care until today. Physical examination shows tachycardia and dry mucous membranes. Laboratory results are as follows:

Which of the following electrolyte findings would most likely be seen in this patient?

Quizplus · Accepted Answer

11ec160b_3ab6_eaa9_9249_6715edd77a69_MD0001_00 This young patient has both clinical (eg, polyuria, polydipsia, volume depletion) and biochemical (eg, hyperglycemia, low bicarbonate, high anion gap, decreased serum sodium levels) signs of diabetic ketoacidosis (DKA). DKA is often precipitated by infections, including urinary tract infections (likely in this patient). Patients with DKA lose significant amounts of potassium in the urine, primarily via glycosuria-induced osmotic diuresis and hypovolemia-mediated increase in aldosterone secretion. This results in a total body potassium deficit that is reflected by decreased intracellular potassium stores (since 98% of the body's potassium is stored intracellularly). Despite the low intracellular potassium levels, extracellular potassium concentrations are normal or increased due to the following mechanisms: Clinicians must be careful when giving insulin and intravenous fluids during resuscitation of dehydrated, hyperglycemic patients. These interventions force potassium back into the cells, causing a precipitous drop in serum potassium due to the total body deficit. Despite normal or elevated serum potassium, timely administration of potassium supplementation is essential when treating a patient with DKA. (Choice A) A decrease in both intra- and extracellular potassium levels is seen with mineralocorticoids excess, diuretic use, and chronic gastrointestinal losses. (Choice B) Extracellular potassium concentration decreases following glucose and insulin administration as potassium moves into the intracellular compartment. Stimulation of beta-adrenergic receptors also causes increased transfer of potassium to the intracellular compartment. (Choice D) Renal excretion of potassium is impaired in most patients with chronic renal failure, resulting in increased total body potassium storage and hyperkalemia. (Choice E) Normal extracellular potassium levels are common in patients with DKA as the extracellular potassium shift is often mitigated by increased urinary potassium losses. However, intracellular potassium levels are always decreased in DKA. Educational objective: Most patients with diabetic ketoacidosis have normal to increased serum potassium levels despite a total body potassium deficit. Replacement of potassium is a crucial step in the management of patients with diabetic ketoacidosis.

A 20-Year-Old Woman Comes to the Emergency Department with Lethargy