A 68-year old man is brought to the emergency room by his daughter due to slurred speech and weakness for the last 12 hours. He has a history of primary hypertension, type 2 diabetes mellitus, and obesity. Three days ago, the patient completed a course of oral prednisone due to severe poison ivy. Temperature is 36.7 C (98 F), blood pressure is 99/80 mm Hg, and pulse is 99/min. BMI is 35 kg/m². On examination, the patient is oriented only to place and is unable to consistently follow commands. The mucous membranes are dry. Neurologic examination reveals dysarthria and muffled speech. The remainder of the physical examination is normal. Laboratory results are as follows: CT scan of the head is normal. Intravenous access is secured, and an infusion of normal saline and regular insulin is started. Which of the following is the best next step in management?

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Explanation: 11ec25c8_d19a_9b6d_bc81_4d6374857e82_MD0003_00 This older patient with type 2 diabetes mellitus likely has hyperosmolar hyperglycemic state (HHS) triggered by recent prednisone use. In HHS, marked hyperglycemia (often >800 mg/dL) and severely elevated plasma osmolality (>320 mOsm/kg) cause dehydration (evidenced by hypotension, dry mucous membranes, elevated blood urea nitrogen-to-creatinine ratio), altered mental status (eg, obtundation, lethargy), and focal neurological signs (eg, dysarthria, seizures). Immediate management includes normal saline and insulin infusion and potassium repletion when potassium is <5.3 mEq/L. plasma osmolality Although laboratory potassium measurements are typically normal or slightly elevated, a total body potassium deficit of 300-600 mEq is present in most patients with HHS as well as in diabetic ketoacidosis (DKA): Potassium deficit is caused by glucose-induced osmotic diuresis (which leads to urinary potassium losses) and secondary hyperaldosteronism from volume contraction. Normal or slightly elevated laboratory potassium measurements are due to hyperosmolality, which draws fluid and potassium into the extracellular space, and insulin deficiency, which reduces cellular uptake of potassium. If potassium is not replenished, life-threatening hypokalemia can result after insulin and intravenous fluid administration, both of which lower plasma osmolality and cause rapid potassium influx into cells. Therefore, in both HHS and DKA, potassium should be frequently monitored and supplemented intravenously when serum potassium falls below 5.3 mEq/L (Choice D). (Choice A) Focal neurological signs (eg, dysarthria) are typically associated with stroke; however, they can also be seen in HHS (possibly from hyperglycemia-induced cerebral injury or inflammation). Given this patient's marked hyperglycemia, HHS is the more likely diagnosis. In addition, this patient has had symptoms for 12 hours and is outside the window of tissue plasminogen activator administration for acute stroke. (Choice B) Although infection is a potential trigger for HHS, potassium repletion should not be delayed given the risk of rapid hypokalemia. Moreover, this patient's recent prednisone use is a more likely cause of HHS. (Choice E) Secondary adrenal insufficiency from glucocorticoid withdrawal (eg, prednisone) can cause altered mentation, hypotension, and hyponatremia. However, hypoglycemia (rather than this patient's severe hyperglycemia) would be expected. This patient's hyponatremia is more likely a result of markedly elevated blood glucose (ie, hyperosmolar hyponatremia). hyperosmolar hyponatremia Educational objective: In hyperosmolar hyperglycemic state, severely elevated glucose (>600 mg/dL) and plasma osmolality are present, causing altered mentation and focal neurological signs. Due to osmotic diuresis and insulin deficiency, total body potassium is often depleted despite normal or slightly elevated serum potassium values. Therefore, in addition to insulin and intravenous fluids, potassium repletion should be given when serum potassium is <5.3 mEq/L. References: Hyperglycemic crises in diabetes. (http://www.ncbi.nlm.nih.gov/pubmed/14693938) Management of hyperglycemic crises: diabetic ketoacidosis and hyperglycemic hyperosmolar state. (http://www.ncbi.nlm.nih.gov/pubmed/28372715)

A 68-Year Old Man Is Brought to the Emergency Room