An 8-year old boy is brought to the emergency department because he has been lethargic and has had several episodes of nausea and vomiting for the past day. He has also had increased thirst over the past two months. He has lost 5.4 kg (11.9 lbs) during this time. He is otherwise healthy and has no history of serious illness. His temperature is 37.5 °C (99.5 °F), blood pressure is 95/68 mm Hg, pulse is 110/min, and respirations are 30/min. He is somnolent and slightly confused. His mucous membranes are dry. Laboratory studies show: Hemoglobin 16.2 g/dL Leukocyte count 9,500/mm3 Platelet count 380,000/mm3 Serum Na+ 130 mEq/L K+ 5.5 mEq/L Cl- 99 mEq/L HCO3- 16 mEq/L Creatinine 1.2 mg/dL Glucose 570 mg/dL Ketones positive Blood gases, arterial pH 7.25 pCO2 21 mm Hg Which of the following is the most appropriate next step in management?

Intravenous hydration with 0.9% normal saline and insulin

Intravenous hydration with 0.45% normal saline and insulin

Intravenous hydration with 5% dextrose solution and 0.45% normal saline

Intravenous hydration with 0.9% normal saline and potassium chloride

An 11-year-old boy is brought to the emergency department because he was found to have severe abdominal pain and vomiting in school. On presentation, he is found to be lethargic and difficult to arouse. His parents noticed that he was eating and drinking more over the last month; however, they attributed the changes to entering a growth spurt. Physical exam reveals deep and rapid breathing as well as a fruity odor on his breath. Which of the following sets of labs would most likely be seen in this patient?

Glucose: 300 mg/dL, pH: 7.2, Bicarbonate: 10 mEq/L

Glucose: 90 mg/dL, pH: 7.4, Bicarbonate: 24 mEq/L

Glucose: 300 mg/dL, pH: 7.4, Bicarbonate: 24 mEq/L

Glucose: 90 mg/dL, pH: 7.2, Bicarbonate: 10 mEq/L

Glucose: 300 mg/dL, pH: 7.4, Bicarbonate: 10 mEq/L

A 27-year-old man presents to the emergency department with his family because of abdominal pain, excessive urination, and drowsiness since the day before. He has had type 1 diabetes mellitus for 2 years. He ran out of insulin 2 days ago. The vital signs at admission include: temperature 36.8°C (98.2°F), blood pressure 102/69 mm Hg, and pulse 121/min. On physical examination, he is lethargic and his breathing is rapid and deep. There is a mild generalized abdominal tenderness without rebound tenderness or guarding. His serum glucose is 480 mg/dL. Arterial blood gas of this patient will most likely show which of the following?

↓ pH, ↓ bicarbonate and ↑ anion gap

↑ pH, ↑ bicarbonate, and normal pCO2

↑ pH, normal bicarbonate and ↓ pCO2

↓ pH, ↓ bicarbonate and normal anion gap

↓ pH, normal bicarbonate and ↑ pCO2

A previously healthy 10-year-old boy is brought to the emergency room by his mother 5 hours after the onset of abdominal pain and nausea. Over the past 2 weeks, he has also had progressive abdominal pain and a 4-kg (8.8-lb) weight loss. The mother reports that her son has been drinking more water than usual during this period. Last week he wet his bed three times despite being completely toilet-trained since 3 years of age. His temperature is 37.8°C (100°F), pulse is 128/min, respirations are 35/min, and blood pressure is 95/55 mm Hg. He appears lethargic. Physical examination shows deep and labored breathing and dry mucous membranes. The abdomen is soft, and there is diffuse tenderness to palpation with no guarding or rebound. Serum laboratory studies show: Na+ 133 mEq/L K+ 5.9 mEq/L Cl- 95 mEq/L HCO3- 13 mEq/L Urea nitrogen 25 mg/dL Creatinine 1.0 mg/dL Urine dipstick is positive for ketones and glucose. Further evaluation is most likely to reveal which of the following?

Serum glucose concentration > 600 mg/dL

A 22-year-old woman with a history of type I diabetes mellitus presents to the emergency department with nausea, vomiting, and drowsiness for the past day. Her temperature is 98.3°F (36.8°C), blood pressure is 114/74 mmHg, pulse is 120/min, respirations are 27/min, and oxygen saturation is 100% on room air. Physical exam is notable for a confused and lethargic young woman. Initial laboratory values are notable for the findings below. Serum: Na+: 139 mEq/L Cl-: 100 mEq/L K+: 2.9 mEq/L HCO3-: 9 mEq/L BUN: 20 mg/dL Glucose: 599 mg/dL Creatinine: 1.1 mg/dL Ca2+: 10.2 mg/dL AST: 12 U/L ALT: 10 U/L An initial ECG is notable for sinus tachycardia. Which of the following is the best initial step in management for this patient?

Normal saline, insulin, and potassium

Normal saline, insulin, potassium, and sodium bicarbonate

A 16-year-old woman presents to the emergency department for evaluation of acute vomiting and abdominal pain. Onset was roughly 3 hours ago while she was sleeping. She has no known past medical history. Her family history is positive for hypothyroidism and diabetes mellitus in her maternal grandmother. On examination, she is found to have fruity breath and poor skin turgor. She appears fatigued and her consciousness is slightly altered. Laboratory results show a blood glucose level of 691 mg/dL, sodium of 125 mg/dL, and elevated serum ketones. Of the following, which is the next best step in patient management?

Administer IV fluids and insulin

Initiate basal-bolus insulin regimen

Initiate insulin glargine 10 units at bedtime only

Initiate oral antidiabetic medications

Initiate insulin aspart at mealtimes only

A 75-year-old woman with late-onset autoimmune diabetes mellitus, rheumatoid arthritis, coronary artery disease, and idiopathic pulmonary fibrosis presents to the ship medic with altered mental status. While on her current cruise to the Caribbean islands, she experienced nausea, vomiting, and diarrhea. She takes aspirin, simvastatin, low-dose prednisone, glargine, and aspart. She is allergic to amoxicillin and shellfish. She works as a greeter at a warehouse and smokes 5 packs/day. Her temperature is 100.5°F (38.1°C), blood pressure is 90/55 mmHg, pulse is 130/min, and respirations are 30/min. Her pupils are equal and reactive to light bilaterally. Her lungs are clear to auscultation bilaterally, but her breath has a fruity odor. She has an early systolic murmur best appreciated at the left upper sternal border. She has reproducible peri-umbilical tenderness. Which of the following will most likely be present in this patient?

Respiratory alkalosis and anion-gap metabolic acidosis

Respiratory acidosis and anion-gap metabolic acidosis

Respiratory alkalosis and non anion-gap metabolic acidosis

Respiratory acidosis and contraction metabolic alkalosis

Respiratory alkalosis and non-contraction metabolic alkalosis

A 20-year-old female with type I diabetes mellitus presents to the emergency department with altered mental status. Her friend said that she has been out late either studying for upcoming tests or attending prayer group meetings. As far as the friend can recollect, the patient appeared to be in her usual state of health until only two days ago, when she was prescribed trimethoprim-sulfamethoxazole for a urinary tract infection. The patient complained that the medication was making her feel nauseous and bloated. The patient also relies on glargine and lispro for glycemic control. Her temperature is 100.5°F (38.1°C), blood pressure is 95/55 mmHg, pulse is 130/min, and respirations are 30/min. Her pupils are equal and reactive to light bilaterally. The remainder of the physical exam is unremarkable. Her basic metabolic panel is displayed below: Serum: Na+: 116 mEq/L Cl-: 90 mEq/L K+: 5.0 mEq/L HCO3-: 2 mEq/L BUN: 50 mg/dL Glucose: 1,200 mg/dL Creatinine: 1.5 mg/dL Which of the following is true regarding this patient's presentation?

Hyperkalemia is independent of the patient's total body potassium stores

Azotemia independently contributes to the patient's encephalopathy

Hyperglycemia to this magnitude supports hyperglycemic hyperosmolar nonketotic syndrome

Hypochloremia to this magnitude supports a pure anion-gap metabolic acidosis

Hyponatremia is independently associated with a poor prognosis

Diabetic ketoacidosis for USMLE Step 1: High-Yield Internal Medicine Lessons

Pathophysiology - Sugar High, Acid Low

Absolute or relative insulin deficiency coupled with ↑ counter-regulatory hormones (glucagon, cortisol, catecholamines) is the central defect.

⭐ The accumulation of ketone bodies (anions) consumes bicarbonate (buffer), creating a high anion gap metabolic acidosis. Calculate it: $Anion~Gap = Na^+ - (Cl^- + HCO_3^-)$.

Presentation & Diagnosis - The Fruity Breath Clue

Classic Triad (3 P's): Polyuria, Polydipsia, Polyphagia.
Dehydration Signs: Tachycardia, hypotension, ↓ skin turgor, dry mucous membranes.
Pathognomonic Signs:
- Kussmaul Respirations: Deep, rapid breaths to compensate for acidosis.
- Fruity Breath: Acetone odor.
- Abdominal pain, nausea/vomiting (can mimic acute abdomen).
- Altered mental status (lethargy, coma).
Diagnostic Criteria (The "D-K-A"):
- Diabetes: Blood Glucose > 250 mg/dL.
- Ketosis: Positive serum or urine ketones.
- Acidosis: Arterial pH < 7.3 AND Serum Bicarbonate < 18 mEq/L.
- Anion Gap: Elevated, $AG = Na^+ - (Cl^- + HCO_3^-)$.

⭐ Despite normal or even high initial serum K+, patients have a profound total body potassium deficit due to transcellular shifts. Insulin therapy will unmask severe hypokalemia if not corrected.

Management & Complications - The Fluid-Insulin Fix

Core goals: Restore volume, correct acidosis/hyperglycemia, replete electrolytes, and treat the precipitate.

IV Fluids (First!):
- Start with 1-2L of 0.9% NaCl (isotonic saline) over the first 1-2 hours.
- When serum glucose reaches ~200-250 mg/dL, switch to D5 1/2 NS to prevent hypoglycemia.
Insulin Therapy:
- Start after initial fluid resuscitation and checking potassium.
- Regular insulin IV infusion at 0.1 U/kg/hr.
- Goal: ↓ glucose by 50-75 mg/dL/hr.
Potassium (K+):
- ⚠️ Total body K+ is depleted, even if serum levels are normal/high.
- Insulin drives K+ into cells, causing rapid ↓ in serum K+. See flowchart for specific management.
Resolution Criteria:
- Glucose < 200 mg/dL
- Anion Gap < 12 mEq/L (Formula: $Na^+ - (Cl^- + HCO_3^-)$)
- Serum HCO3 ≥ 15 mEq/L

⭐ The most common iatrogenic complication and cause of mortality in pediatric DKA is cerebral edema, often due to overaggressive fluid resuscitation and rapid reduction in plasma osmolality.

DKA is a triad of hyperglycemia, ketosis, and anion gap metabolic acidosis.

Primarily in Type 1 Diabetes, often precipitated by infection or insulin non-compliance.

Presents with Kussmaul respirations and a characteristic fruity breath odor.

First step in management is always aggressive IV fluid resuscitation, followed by IV insulin.

Total body potassium is depleted, although serum levels may be normal or high initially.

Monitor and correct hypokalemia as insulin will shift potassium into cells.

The primary therapeutic goal is to close the anion gap.

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