An 18-year-old woman presents to the emergency department with lethargy for 10 days and abdominal pain for the past 2 days. She feels that she has lost weight, as her clothes have become loose. She mentions that she is always thirsty and has to go to the bathroom three times in the middle of the night. Her last menstrual period was 2 weeks ago. Past medical history is negative, and she does not take any medications. She does not consume alcohol or use illicit drugs. Vital signs are temperature 98.6°F (37.0°C), blood pressure 108/66 mmHg, pulse 110 beats/min, and respirations 20/min. On physical examination, she has dry mucous membranes tachycardia. She has diffuse abdominal tenderness to palpation but no rebound or guarding.
Which of the following is the most appropriate next step in the management of this patient?
D) Fingerstick blood glucose measurement
The patient's symptoms of lethargy, weight loss, excessive thirst (polydipsia), and frequent urination (polyuria) are classic signs of diabetes mellitus, particularly diabetic ketoacidosis (DKA). Type 1 diabetes mellitus (DM) often presents in young patients, and DKA can be the initial manifestation. If left untreated, DKA can lead to severe complications such as altered mental status, hyperventilation, and abdominal pain. The best initial test is to measure to perform a fingerstick blood glucose test while waiting for the plasma glucose level to confirm hyperglycemia. In cases of DKA, blood glucose levels are typically above 300 mg/dL. Additionally, an arterial blood gas (ABG) test will usually show metabolic acidosis (bicarbonate < 18 mEq/L) with a high anion gap. Ketones may also be present in both serum and urine.
Upon diagnosis, Fluid repletion may be initiated with isotonic saline (0.9 percent sodium chloride [NaCl]) or isotonic buffered crystalloid (e.g., lactated Ringer solution) and insulin to reduce blood glucose levels. Potassium should also be administered if the serum potassium level is less than 5.3 mEq/L to prevent hypokalemia during insulin therapy. If the initial serum potassium is 3.3 to 5.3 mEq/L, intravenous KCl (20 to 30 mEq) is added to each liter of intravenous replacement fluid. Adjust potassium replacement to maintain the serum potassium concentration in the range of 4 to 5 mEq/L.
Most guidelines recommend initiating treatment with low-dose IV insulin in all patients with moderate to severe DKA who have a serum potassium ≥3.3 mEq/L. The only indication for delaying the initiation of insulin therapy is if the serum potassium is below 3.3 mEq/L since insulin will worsen the hypokalemia by driving potassium into the cells. Subcutaneous insulin protocols are being used with increasing frequency to treat selected patients with mild to moderate DKA. Treatment of DKA with subcutaneous insulin has not been evaluated in severely ill patients. In mild DKA, direct comparison of intramuscular, subcutaneous, and IV insulin therapy for hemodynamically stable DKA patients shows similar efficacy and safety
Answer choice A: Abdominal x-ray, is incorrect. An abdominal X-ray is not indicated as the initial test because the symptoms described (lethargy, weight loss, polydipsia, polyuria) are more suggestive of a metabolic disorder rather than a primary gastrointestinal issue.
Answer choice B: Blood cultures and antibiotics, is incorrect. There are no obvious signs of infection such as fever, making blood cultures and antibiotics inappropriate as the first step.
Answer choice C: Dextrose saline infusion, is incorrect. Administering dextrose saline infusion without knowing the patient's blood glucose level could worsen hyperglycemia if the patient is experiencing diabetic ketoacidosis (DKA).
Answer choice E: Subcutaneous insulin administration, is incorrect. While insulin is necessary for treating DKA, it not administered before confirming blood glucose and serum potassium levels.
Key Learning Point
Lethargy, weight loss, polydipsia, and polyuria are classic signs of diabetic ketoacidosis (DKA), a serious complication of diabetes mellitus, usually from type 1 diabetes. The best initial test to confirm hyperglycemia and diagnose DKA is a fingerstick blood glucose test while waiting for the plasma glucose level.
