Diabetic ketoacidosis US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Diabetic ketoacidosis. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Diabetic ketoacidosis US Medical PG Question 1: A 14-year-old female with no past medical history presents to the emergency department with nausea and abdominal pain. On physical examination, her blood pressure is 78/65, her respiratory rate is 30, her breath has a fruity odor, and capillary refill is > 3 seconds. Serum glucose is 820 mg/dL. After starting IV fluids, what is the next best step in the management of this patient?
- A. Intravenous Dextrose in water
- B. Subcutaneous insulin glargine
- C. Intravenous regular insulin (Correct Answer)
- D. Intravenous glucagon
- E. Subcutaneous insulin lispro
Diabetic ketoacidosis Explanation: ***Intravenous regular insulin***
- The patient presents with **diabetic ketoacidosis (DKA)**, characterized by **hyperglycemia**, **fruity breath** (due to ketones), and **hypotension**. Prompt administration of **intravenous regular insulin** is crucial to lower blood glucose and resolve ketoacidosis.
- **Regular insulin** is preferred intravenously due to its **rapid onset** and short duration of action, allowing for precise titration and continuous adjustment based on glucose levels.
*Intravenous Dextrose in water*
- **Dextrose** would further increase the already severely elevated blood glucose level in a patient with DKA, worsening the metabolic derangements.
- Dextrose is typically initiated only after blood glucose drops to safe levels (<200 mg/dL) to prevent **hypoglycemia** during insulin infusion.
*Subcutaneous insulin glargine*
- **Insulin glargine** is a **long-acting insulin** designed for basal insulin coverage, not for acute management of severe hyperglycemia or DKA.
- Its **slow onset of action** and prolonged effect make it unsuitable for the urgent and rapid glucose reduction required in DKA.
*Intravenous glucagon*
- **Glucagon** is a hormone that **raises blood glucose levels**, counteracting the effects of insulin.
- Administering glucagon would exacerbate the severe hyperglycemia present in DKA and is used only in cases of severe hypoglycemia.
*Subcutaneous insulin lispro*
- **Insulin lispro** is a **rapid-acting insulin analog** but is typically given subcutaneously.
- While faster than regular insulin subcutaneously, the **subcutaneous route** has variable absorption in critically ill patients, and the immediate and precisely controllable effect of intravenous regular insulin is needed in DKA.
Diabetic ketoacidosis US Medical PG Question 2: 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?
- A. Intravenous hydration with 0.45% normal saline and insulin
- B. Intravenous hydration with 5% dextrose solution and 0.45% normal saline
- C. Intravenous sodium bicarbonate
- D. Intravenous hydration with 0.9% normal saline and insulin (Correct Answer)
- E. Intravenous hydration with 0.9% normal saline and potassium chloride
Diabetic ketoacidosis Explanation: ***Intravenous hydration with 0.9% normal saline and insulin***
- This patient presents with **diabetic ketoacidosis (DKA)**, characterized by hyperglycemia (glucose 570 mg/dL), metabolic acidosis (pH 7.25, HCO3- 16 mEq/L, ketones positive), and dehydration (dry mucous membranes, increased thirst, weight loss).
- Initial management of DKA involves aggressive **volume expansion** with **0.9% normal saline** to restore perfusion and reduce hyperglycemia; subsequently, **insulin infusion** is started to correct hyperglycemia and halt ketogenesis.
*Intravenous hydration with 0.45% normal saline and insulin*
- While insulin is crucial, **0.45% normal saline (hypotonic saline)** is generally not the initial fluid of choice for DKA due to the risk of exacerbating cerebral edema, especially in children.
- **Isotonic saline (0.9% normal saline)** is preferred for initial resuscitation to rapidly restore extracellular fluid volume.
*Intravenous hydration with 5% dextrose solution and 0.45% normal saline*
- **5% dextrose solution** should only be added to intravenous fluids when the blood glucose level falls to around 200-250 mg/dL, to prevent hypoglycemia while continuing insulin to resolve ketosis.
- Administering dextrose initially would worsen the existing severe hyperglycemia.
*Intravenous sodium bicarbonate*
- **Sodium bicarbonate** is generally not recommended for mild to moderate DKA due to potential risks like cerebral edema and metabolic alkalosis, and potential paradoxical worsening of CNS acidosis.
- Bicarbonate therapy is reserved for **severe acidosis (pH < 6.9 or 7.0)** with hemodynamic instability or impaired cardiac contractility, which is not the case here.
*Intravenous hydration with 0.9% normal saline and potassium chloride*
- While **0.9% normal saline** is appropriate, this option lacks **insulin therapy**, which is essential for treating DKA by halting ketogenesis and correcting hyperglycemia.
- Although potassium supplementation will be necessary during DKA treatment (as insulin drives K+ into cells and can cause hypokalemia), the most appropriate **next step** is to initiate both fluid resuscitation and insulin therapy together.
- The patient's current potassium level of 5.5 mEq/L is at the upper limit of normal, but reflects total body potassium depletion; potassium should be added to maintenance fluids once adequate urine output is established.
Diabetic ketoacidosis US Medical PG Question 3: 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?
- A. Glucose: 90 mg/dL, pH: 7.4, Bicarbonate: 24 mEq/L
- B. Glucose: 300 mg/dL, pH: 7.4, Bicarbonate: 24 mEq/L
- C. Glucose: 90 mg/dL, pH: 7.2, Bicarbonate: 10 mEq/L
- D. Glucose: 300 mg/dL, pH: 7.4, Bicarbonate: 10 mEq/L
- E. Glucose: 300 mg/dL, pH: 7.2, Bicarbonate: 10 mEq/L (Correct Answer)
Diabetic ketoacidosis Explanation: ***Glucose: 300 mg/dL, pH: 7.2, Bicarbonate: 10 mEq/L***
- The patient's symptoms (polydipsia, polyphagia, lethargy, abdominal pain, vomiting, deep and rapid breathing, fruity breath) are classic for **Diabetic Ketoacidosis (DKA)**, which involves **hyperglycemia**, **metabolic acidosis** (low pH and bicarbonate), and **ketone production**.
- A glucose level of 300 mg/dL indicates significant hyperglycemia, a pH of 7.2 shows acidosis, and a bicarbonate of 10 mEq/L confirms the metabolic component of DKA.
*Glucose: 90 mg/dL, pH: 7.4, Bicarbonate: 24 mEq/L*
- These values represent normal glucose, pH, and bicarbonate levels, which are entirely inconsistent with the patient's severe symptoms of **DKA** and metabolic derangement.
- A glucose of 90 mg/dL is within the normal range, and a pH of 7.4 with a bicarbonate of 24 mEq/L indicates a normal acid-base balance.
*Glucose: 300 mg/dL, pH: 7.4, Bicarbonate: 24 mEq/L*
- While a glucose of 300 mg/dL indicates hyperglycemia, the normal pH and bicarbonate levels (7.4 and 24 mEq/L respectively) do not align with the **metabolic acidosis** characteristic of DKA.
- The patient's presentation with **Kussmaul breathing** and fruity breath are strong indicators of acidosis, which is absent in these lab values.
*Glucose: 90 mg/dL, pH: 7.2, Bicarbonate: 10 mEq/L*
- Although the low pH and bicarbonate suggest **metabolic acidosis**, the normal glucose level of 90 mg/dL rules out **hyperglycemia**, which is a prerequisite for a diagnosis of DKA.
- The combination of severe acidosis and normal glucose is indicative of other causes of metabolic acidosis, but not DKA.
*Glucose: 300 mg/dL, pH: 7.4, Bicarbonate: 10 mEq/L*
- This set of labs shows hyperglycemia (glucose 300 mg/dL) and low bicarbonate, but the **normal pH (7.4)** is inconsistent with the severe metabolic acidosis expected in DKA, especially given the patient's symptoms like Kussmaul breathing.
- A patient with significant bicarbonate depletion (10 mEq/L) due to DKA would typically have a significantly lower, acidotic pH.
Diabetic ketoacidosis US Medical PG Question 4: 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?
- A. ↑ pH, ↑ bicarbonate, and normal pCO2
- B. ↓ pH, ↓ bicarbonate and ↑ anion gap (Correct Answer)
- C. ↑ pH, normal bicarbonate and ↓ pCO2
- D. ↓ pH, ↓ bicarbonate and normal anion gap
- E. ↓ pH, normal bicarbonate and ↑ pCO2
Diabetic ketoacidosis Explanation: ***↓ pH, ↓ bicarbonate and ↑ anion gap***
- The patient's symptoms (abdominal pain, excessive urination, drowsiness, rapid and deep breathing, hyperglycemia) and history of Type 1 diabetes with missed insulin are highly suggestive of **diabetic ketoacidosis (DKA)**.
- DKA is characterized by **metabolic acidosis** due to the accumulation of ketone bodies, leading to a **decreased pH**, consumption of bicarbonate and thus a **decreased bicarbonate level**, and an **increased anion gap**.
*↑ pH, ↑ bicarbonate, and normal pCO2*
- This pattern suggests a **metabolic alkalosis**, which is inconsistent with the patient's presentation of DKA.
- Metabolic alkalosis is typically seen in conditions like severe vomiting or diuretic use, not uncontrolled diabetes.
*↑ pH, normal bicarbonate and ↓ pCO2*
- This profile describes **respiratory alkalosis**, often caused by primary hyperventilation.
- While the patient has rapid and deep breathing (Kussmaul respiration), this is a compensatory mechanism for metabolic acidosis, not a primary respiratory alkalosis.
*↓ pH, ↓ bicarbonate and normal anion gap*
- This indicates a **normal anion gap metabolic acidosis**, also known as hyperchloremic acidosis.
- This is typically seen in conditions like renal tubular acidosis or severe diarrhea, where bicarbonate is lost or chloride is retained, which is not the case for DKA.
*↓ pH, normal bicarbonate and ↑ pCO2*
- This presentation indicates **respiratory acidosis**, which is caused by hypoventilation and retention of CO2.
- The patient's rapid and deep breathing (Kussmaul breathing) is a compensatory mechanism to blow off CO2 and would decrease pCO2, not increase it.
Diabetic ketoacidosis US Medical PG Question 5: 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?
- A. Serum glucose concentration > 600 mg/dL
- B. Increased total body sodium
- C. Increased arterial pCO2
- D. Hypervolemia
- E. Decreased total body potassium (Correct Answer)
Diabetic ketoacidosis Explanation: **Decreased total body potassium**
- Despite **hyperkalemia** on serum labs, patients with **diabetic ketoacidosis (DKA)** often have a **total body potassium deficit** due to increased renal losses and intracellular-to-extracellular shifts.
- The combination of polyuria, vomiting, and acidemia all contribute to significant potassium disturbances.
*Serum glucose concentration > 600 mg/dL*
- A glucose level of **over 600 mg/dL** is more characteristic of **hyperglycemic hyperosmolar state (HHS)**, not typically seen in pediatric DKA.
- While DKA involves hyperglycemia, severe dehydration and altered mentation typically occur at lower glucose thresholds in DKA.
*Increased total body sodium*
- Patients with DKA are typically **hypovolemic and hyponatremic** (even if serum sodium appears normal due to pseudohyponatremia) due to osmotic diuresis caused by hyperglycemia.
- There is no mechanism in DKA that would lead to an increase in total body sodium.
*Increased arterial pCO2*
- The patient's **deep and labored breathing (Kussmaul respirations)** is a compensatory mechanism to **blow off CO2** and correct the metabolic acidosis.
- Therefore, arterial pCO2 would be **decreased**, not increased.
*Hypervolemia*
- **Polyuria** (increased urination) due to osmotic diuresis and poor oral intake typically leads to **hypovolemia and dehydration** in DKA patients.
- The patient exhibits signs of dehydration such as dry mucous membranes, increased pulse, and low blood pressure.
Diabetic ketoacidosis US Medical PG Question 6: A 20-year-old male is brought by ambulance to the emergency room in extremis. He is minimally conscious, hypotensive, and tachypneic, and his breath gives off a "fruity" odor. An arterial blood gas and metabolic panel show anion gap metabolic acidosis. This patient is most likely deficient in which of the following metabolic actions?
- A. Glucagon production
- B. Cortisol secretion
- C. Formation of ketone bodies
- D. Glucose production
- E. Cellular uptake of glucose (Correct Answer)
Diabetic ketoacidosis Explanation: ***Cellular uptake of glucose***
- The patient's symptoms, including **fruity odor breath**, **anion gap metabolic acidosis**, and being found in extremis, are classic signs of **diabetic ketoacidosis (DKA)**.
- DKA results from a profound lack of **insulin**, which is essential for cells (especially muscle and adipose tissue) to take up glucose from the bloodstream, leading to hyperglycemia and a shift to fat metabolism.
*Glucagon production*
- **Glucagon** is a counter-regulatory hormone that *raises* blood glucose levels, and its production is often *increased* in DKA as the body attempts to provide fuel to cells in the absence of insulin's effect.
- A deficiency in glucagon production would more likely lead to **hypoglycemia**, not the profound hyperglycemia seen in DKA.
*Cortisol secretion*
- **Cortisol** is another counter-regulatory hormone that *increases* blood glucose, and its secretion is typically *elevated* in stress states like DKA.
- A deficiency in cortisol (e.g., in adrenal insufficiency) would present with different symptoms such as **hypoglycemia**, **hyponatremia**, and **hyperkalemia**, without the classic DKA picture.
*Formation of ketone bodies*
- The patient's **fruity odor breath** and **anion gap metabolic acidosis** are direct consequences of the *overproduction* of **ketone bodies**.
- This overproduction occurs when the body, lacking glucose for fuel due to insulin deficiency, switches to **fat metabolism**, leading to excessive formation of acetoacetate, beta-hydroxybutyrate, and acetone.
*Glucose production*
- **Glucose production** (gluconeogenesis and glycogenolysis) is typically *increased* in DKA as the liver tries to supply glucose to the body due to perceived cellular starvation (despite high blood glucose).
- A deficiency in glucose production, such as in certain glycogen storage diseases or severe liver failure, would lead to **hypoglycemia**, not the hyperglycemia characteristic of DKA.
Diabetic ketoacidosis US Medical PG Question 7: 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?
- A. Normal saline and insulin
- B. Insulin and potassium
- C. Normal saline and potassium
- D. Normal saline, insulin, and potassium (Correct Answer)
- E. Normal saline, insulin, potassium, and sodium bicarbonate
Diabetic ketoacidosis Explanation: ***Normal saline, insulin, and potassium***
- This patient presents with signs and symptoms consistent with **diabetic ketoacidosis (DKA)**, including hyperglycemia (glucose 599 mg/dL), metabolic acidosis (HCO3- 9 mEq/L, respiratory compensation with elevated respiratory rate), and altered mental status. The initial management of DKA involves aggressive **intravenous fluid resuscitation** (normal saline), **insulin administration** to correct hyperglycemia and acidosis, and **potassium replacement** due to total body potassium depletion and anticipated further drop with insulin therapy.
- Her **hypokalemia (2.9 mEq/L)**, even before insulin administration, necessitates immediate potassium repletion as insulin drives potassium intracellularly, which could worsen hypokalemia and lead to arrhythmias.
*Normal saline and insulin*
- While fluid resuscitation and insulin are crucial for DKA management, omitting **potassium replacement** in a patient with initial hypokalemia (K+ 2.9 mEq/L) would be inappropriate and potentially dangerous.
- Failure to correct hypokalemia before or with insulin administration can precipitate life-threatening **cardiac arrhythmias**.
*Normal saline, insulin, potassium, and sodium bicarbonate*
- **Sodium bicarbonate** is generally not recommended for DKA unless pH is extremely low (typically <6.9), as it can worsen cerebral edema and hypokalemia. The patient's bicarbonate of 9 mEq/L and presumably higher pH does not warrant bicarbonate administration.
- While fluids, insulin, and potassium are essential, the addition of sodium bicarbonate is usually reserved for severe, life-threatening acidosis (pH < 6.9).
*Normal saline and potassium*
- Administering only normal saline and potassium would address dehydration and hypokalemia but would fail to correct the underlying **hyperglycemia** and **ketoacidosis**, which are the core pathologies of DKA.
- **Insulin** is critical to stop ketogenesis and lower blood glucose.
*Insulin and potassium*
- Administering insulin and potassium without **fluid resuscitation** would be inadequate. The patient is likely significantly dehydrated due to osmotic diuresis from hyperglycemia and vomiting.
- **Fluid administration** is paramount in restoring circulating volume, improving renal perfusion, and reducing hyperglycemia by enhancing glucose excretion.
Diabetic ketoacidosis US Medical PG Question 8: 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?
- A. Administer IV fluids and insulin (Correct Answer)
- B. Initiate basal-bolus insulin regimen
- C. Initiate insulin glargine 10 units at bedtime only
- D. Initiate oral antidiabetic medications
- E. Initiate insulin aspart at mealtimes only
Diabetic ketoacidosis Explanation: ***Administer IV fluids and insulin***
- The patient presents with **fruity breath**, **altered consciousness**, **hyperglycemia (691 mg/dL)**, **hyponatremia**, and **elevated serum ketones**, which are classic signs of **diabetic ketoacidosis (DKA)**.
- The immediate management for DKA involves aggressive **intravenous fluid resuscitation** to correct dehydration and hypovolemia, followed by a continuous **intravenous insulin infusion** to lower blood glucose and suppress ketogenesis.
*Initiate basal-bolus insulin regimen*
- A **basal-bolus insulin regimen** is appropriate for long-term management of diabetes but is not the immediate treatment for acute DKA, which requires continuous intravenous insulin.
- This approach does not address the severe dehydration and electrolyte imbalances seen in DKA, which need urgent fluid replacement.
*Initiate insulin glargine 10 units at bedtime only*
- **Insulin glargine** is a long-acting insulin used for basal insulin coverage, typically in the chronic management of diabetes.
- This dose is insufficient to manage acute DKA, and it also fails to address the critical need for fluid resuscitation.
*Initiate oral antidiabetic medications*
- **Oral antidiabetic medications** are suitable for individuals with type 2 diabetes or milder forms of insulin resistance, not for acute DKA.
- They are ineffective in severe hyperglycemia and metabolic acidosis characteristic of DKA, and do not address dehydration.
*Initiate insulin aspart at mealtimes only*
- **Insulin aspart** is a rapid-acting insulin used to cover mealtime glucose excursions.
- Administering it only at mealtimes is inadequate for acute DKA, which requires continuous insulin infusion and aggressive fluid management.
Diabetic ketoacidosis US Medical PG Question 9: 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?
- A. Respiratory alkalosis and anion-gap metabolic acidosis (Correct Answer)
- B. Respiratory acidosis and anion-gap metabolic acidosis
- C. Respiratory alkalosis and non anion-gap metabolic acidosis
- D. Respiratory acidosis and contraction metabolic alkalosis
- E. Respiratory alkalosis and non-contraction metabolic alkalosis
Diabetic ketoacidosis Explanation: ***Respiratory alkalosis and anion-gap metabolic acidosis***
- The patient's **fruity-smelling breath**, history of diabetes, and symptoms of nausea, vomiting, and diarrhea strongly suggest **diabetic ketoacidosis (DKA)**, which causes a **high anion-gap metabolic acidosis** from accumulation of ketoacids (beta-hydroxybutyrate and acetoacetate).
- The markedly increased respiratory rate (30/min) represents **Kussmaul breathing** - a compensatory hyperventilation mechanism attempting to blow off CO2 and normalize pH. While this is technically **respiratory compensation for metabolic acidosis** rather than a primary respiratory alkalosis, the arterial blood gas will show a **low PaCO2** (respiratory alkalosis pattern) alongside the **low pH and low HCO3** (metabolic acidosis).
- This represents a **partially compensated metabolic acidosis** with high anion gap, which is the classic acid-base disturbance in DKA.
*Respiratory acidosis and anion-gap metabolic acidosis*
- **Respiratory acidosis** would imply hypoventilation (decreased respiratory rate or impaired ventilation) with CO2 retention, which is contrary to the patient's markedly elevated respiratory rate (30/min). The patient is hyperventilating, not hypoventilating.
- While **anion-gap metabolic acidosis** is correct due to DKA, the respiratory component is incorrect.
*Respiratory alkalosis and non anion-gap metabolic acidosis*
- While the low PaCO2 from compensatory hyperventilation would be present, **non-anion-gap metabolic acidosis** is incorrect.
- **Non-anion-gap metabolic acidosis** is typically caused by conditions like diarrhea (GI HCO3 loss) or renal tubular acidosis, whereas DKA characteristically causes a **high anion-gap metabolic acidosis** due to accumulation of unmeasured anions (ketoacids).
*Respiratory acidosis and contraction metabolic alkalosis*
- This option incorrectly identifies both acid-base components. The patient is **hyperventilating** (not hypoventilating), ruling out respiratory acidosis.
- **Contraction alkalosis** occurs with severe volume depletion and diuretic use when chloride depletion leads to metabolic alkalosis, which does not fit the DKA presentation where ketoacid accumulation causes metabolic acidosis.
*Respiratory alkalosis and non-contraction metabolic alkalosis*
- While the compensatory hyperventilation results in low PaCO2, **metabolic alkalosis** (whether contraction or non-contraction) is inconsistent with DKA, which causes metabolic **acidosis**, not alkalosis.
- **Non-contraction metabolic alkalosis** is associated with conditions like hyperaldosteronism or vomiting with gastric acid loss, not with ketoacid accumulation.
Diabetic ketoacidosis US Medical PG Question 10: 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?
- A. Azotemia independently contributes to the patient's encephalopathy
- B. Hyperglycemia to this magnitude supports hyperglycemic hyperosmolar nonketotic syndrome
- C. Hypochloremia to this magnitude supports a pure anion-gap metabolic acidosis
- D. Hyponatremia is independently associated with a poor prognosis
- E. Hyperkalemia is independent of the patient's total body potassium stores (Correct Answer)
Diabetic ketoacidosis Explanation: ***Hyperkalemia is independent of the patient's total body potassium stores***
- In **diabetic ketoacidosis (DKA)**, intracellular potassium shifts extracellularly due to **acidemia** and **insulin deficiency**, leading to **normal or elevated serum potassium** despite depleted total body potassium stores.
- The patient's presentation with **DKA** (hyperglycemia, acidosis, altered mental status) coupled with a normal serum potassium level in the setting of significant fluid loss suggests a substantial deficit in total body potassium.
*Azotemia independently contributes to the patient's encephalopathy*
- While the patient has **elevated BUN and creatinine**, indicating **azotemia**, the primary cause of her altered mental status is likely **diabetic ketoacidosis (DKA)** with severe **hyperglycemia** and **acidosis**, leading to an **osmolar shift** and brain edema.
- Although severe azotemia can cause encephalopathy, in this context, the profound metabolic derangements of DKA are the more prominent contributors to her altered mental status.
*Hyperglycemia to this magnitude supports hyperglycemic hyperosmolar nonketotic syndrome*
- Although the glucose level is very high (1200 mg/dL), the presence of **severe metabolic acidosis** (HCO3- 2 mEq/L) is characteristic of **diabetic ketoacidosis (DKA)**, not hyperglycemic hyperosmolar nonketotic syndrome (HHNS).
- **HHNS** is typically characterized by extreme hyperglycemia, hyperosmolarity, and dehydration, but with **minimal or no ketosis or acidosis**.
*Hypochloremia to this magnitude supports a pure anion-gap metabolic acidosis*
- The patient has a **high anion-gap metabolic acidosis** (calculated anion gap = Na+ - (Cl- + HCO3-) = 116 - (90 + 2) = 24), which is characteristic of DKA.
- The **hypochloremia** is secondary to the profound dehydration and is often a response to the acidosis, but the primary acidosis is high anion-gap, not pure non-anion gap (hyperchloremic) acidosis.
*Hyponatremia is independently associated with a poor prognosis*
- The **hyponatremia** in this patient is largely **pseudohyponatremia** due to severe hyperglycemia, which draws water out of cells and dilutes serum sodium.
- While severe hyponatremia can indicate a poor prognosis in other contexts, in DKA, it often reflects the severity of hyperglycemia and dehydration, and corrects with resolution of hyperglycemia and fluid resuscitation; it is not an independent prognostic factor in this setting.
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