Electrolyte disorders (Na, K, Ca, Mg)Downloads

A 52-year-old woman is brought to the emergency department by her husband because of weakness, abdominal pain, and a productive cough for 4 days. She also reports increased urination for the past 2 days. This morning, she had nausea and five episodes of vomiting. She has type 1 diabetes mellitus and hypertension. Current medications include insulin and lisinopril. She admits to have forgotten to take her medication in the last few days. Her temperature is 38.4°C (101.1°F), pulse is 134/min, respirations 31/min, and blood pressure is 95/61 mm Hg. Examination shows dry mucous membranes and decreased skin turgor. Abdominal examination shows diffuse tenderness with no guarding or rebound. Bowel sounds are normal. Laboratory studies show: Serum Na+ 139 mEq/L K+ 5.3 mEq/L Cl- 106 mEq/L Glucose 420 mg/dL Creatinine 1.0 mg/dL Urine Blood negative Glucose 4+ Ketones 3+ Arterial blood gas analysis on room air shows: pH 7.12 pCO2 17 mm Hg pO2 86 mm Hg HCO3- 12 mEq/L Which of the following is the most likely underlying cause of this patient's increased potassium?

A physician at an internal medicine ward notices that several of his patients have hyponatremia without any associated symptoms. Severe hyponatremia, often defined as < 120 mEq/L, is associated with altered mental status, coma, and seizures, and warrants treatment with hypertonic saline. Because some patients are chronically hyponatremic, with serum levels < 120 mEq/L, but remain asymptomatic, the physician is considering decreasing the cutoff for severe hyponatremia to < 115 mEq/L. Changing the cutoff to < 115 mEq/L would affect the validity of serum sodium in predicting severe hyponatremia requiring hypertonic saline in which of the following ways?