A family reports that their 5-year-old son has been increasingly confused over the last several hours. His emergency department vital signs show a heart rate of 180 beats/min, a blood pressure of 80/50 mm Hg, a temperature of 36.1 °C (97°F), and slow, deep respirations. His capillary refill is 5 seconds, and he has skin tenting as well as altered mental status. His mother reports that he has had a several pounds of weight loss over the last few weeks, has been increasingly tired for several days, and that she has been concerned about his 2- or 3-day history of thirst, frequent daytime urination, and new onset of nocturnal enuresis.
What is the most likely diagnosis?
What is the best therapy?
ANSWERS TO CASE 8: Diabetic Ketoacidosis
Summary: A 5-year-old with weight loss, polydipsia, and polyuria who presents with dehydration and Kussmaul breathing.
• Most likely diagnosis: Diabetic ketoacidosis (DKA).
• Best therapy: Fluid rehydration, insulin, and close monitoring of serum glucose level and acidemia.
ANALYSIS
Objectives
1. Understand the presentation of patients in DKA.
2. Appreciate the initial treatment strategies in the management of DKA.
3. Become familiar with pitfalls in the treatment of DKA.
Considerations
This patient is in extremis. He is tachycardic, hypotensive, hypothermic, and has delayed capillary refill with tenting of the skin. The ABCs of medicine apply. He is confused but not obtunded; he probably requires neither his Airway controlled nor his Breathing regulated. His examination suggests at least 10% dehydration; his Circulatory status is marginal and requires rapid volume restoration. His history and physical examination suggest diabetes; a finger-stick glucose test confirms the diagnosis. The therapy for DKA rests on: (1) aggressive volume repletion, (2) glucose control with insulin, and (3) correction of metabolic abnormalities.
APPROACH TO:
Diabetic Ketoacidosis
DEFINITIONS
KETOACIDOSIS: A condition resulting from deficient insulin availability, leading to lipid oxidation and metabolism rather than glucose metabolism. The insulin absence results in free fatty acid (FFA) released from adipose tissue and in unregulated hepatic FFA oxidation and ketogenesis.
TYPE I DIABETES: Known by a variety of names, it is caused by a severe endogenous insulin deficiency and a requirement for exogenous insulin to prevent ketoacidosis.
TYPE II DIABETES: Known by a variety of names, it usually consists of tissue-level insulin resistance (although exogenous insulin is often required) and rarely leads to ketoacidosis.
KUSSMAUL BREATHING: Deep, rapid respirations associated with acidosis.
CLINICAL APPROACH
Patients with DKA represent a medical emergency. Such patients may require intubation, but usually this is seen later in the disease course. Children more commonly present signs and symptoms of severe dehydration and acidosis. The history often is positive for polyuria, polydipsia, nausea, vomiting, and abdominal complaints. Hypothermia, hypotension, Kussmaul respirations, and acetone on the breath are common. As these signs and symptoms may be nonspecific, especially in younger children, a high index of suspicion is required to make the diagnosis.
Laboratory data demonstrate an elevated glucose level (often 400-800 mg/dL), metabolic acidosis (with anion gap, ie, excess endogenous anion production such as from lactic acid), and hyperketonemia.Serum electrolyte levels usually show hyponatremia and normal or slightly elevated potassium (despite potentially serious intracellular potassium depletion). Elevated blood urea nitrogen and creatinine levels are commonly seen, reflecting the dehydration. White blood cell counts (WBCs) often are elevated, especially if a bacterial infection is exacerbating the condition.
Treating DKA includes initial vascular volume expansion (often with normal saline) and then correction of the hyperglycemia and hyperketonemia. Intravenous (IV) fluid boluses sufficient to stabilize the heart rate and blood pressure are often required, and then a slower IV rate (usually a saline solution with or without some glucose) to replace fluid losses and to ensure adequate urine flow is initiated. Potassium is added to IV fluids after urine output is established to counteract the patient’s total body potassium depletion (treatment of the hyperglycemia and acidosis drives potassium intracellularly; hypokalemia is an avoidable life-threatening complication). A continuous insulin infusion at a rate of approximately 0.1 U/kg/h is also started (a bolus of 0.1 U/kg is often given initially), with the IV rate adjusted based on the results of hourly glucose measurements. Glucose is added to IV fluids when the serum glucose level drops to approximately 250 or 300 mg/dL, and additional insulin rate adjustments are made based on serum glucose levels. The low plasma pH and elevated serum ketone levels will correct significantly in the first 8 to 10 hours; the serum bicarbonate level may remain low for 24 hours or more. Improvement is characterized by a decrease in IV insulin doses and resolution of the ketonuria; then, the patient can take oral feedings, and insulin is converted from the IV to subcutaneous route.
Several pitfalls should be avoided during the treatment of DKA. Intravenous fluids with insulin and improvement in acidosis levels often are associated with a fall in serum potassium levels; addition of potassium to the IV fluids usually is indicated to prevent serious hypokalemia. Bicarbonate infusion usually is avoided except in extreme situations, because it may: (1) precipitate hypokalemia, (2) shift the oxygen dissociation curve to the left, worsening organ oxygen delivery, (3) overcorrect the acidosis, and (4) result in worsening cerebral acidosis while the plasma pH is being corrected (transfer into the cerebrum of CO2 formed when the bicarbonate is infused in an acid serum). Cerebral edema (etiology unknown) sometimes occurs, manifesting as headache, personality changes, vomiting, and decreased reflexes. Treatment of cerebral edema consists of reduction in IV fluid, administration of IV mannitol, and hyperventilation. Episodes of DKA (especially in the known diabetic) can be precipitated by bacterial infection. An evaluation for infection sources with institution of antibiotics (if appropriate) is required.
COMPREHENSION QUESTIONS
8.1 A 14-year-old adolescent girl from another state was monitored for 7 years for a history of insulin-dependent diabetes mellitus. At your clinic her hemoglobin A1C is 14.9%. This laboratory test indicates which of the following?
A. Her glucose control is poor.
B. She does not have insulin-dependent diabetes.
C. She has entered the “honeymoon phase” of her diabetes.
D. She has an underlying infection.
E. She is demonstrating the Somogyi phenomenon.
8.2 Six months after being diagnosed with what appears to be insulin-dependent diabetes, the 5-year-old in the case presentation has a significant decrease in his insulin requirement. Which of the following is the most likely explanation?
A. His diagnosis of insulin-dependent diabetes was incorrect.
B. He had a chronic infection that is now under control.
C. He has followed his diabetes diet so well that he requires less insulin.
D. He is demonstrating the Somogyi phenomenon.
E. He has entered the “honeymoon phase” of his diabetes.
8.3 A 15-year-old adolescent girl has experienced abdominal pain, vomiting, and lethargy for 3 days. Her chest and throat examinations are clear, but her abdominal examination is significant for right lower quadrant pain. Rectal examination is equivocal for pain, and her pelvic examination is remarkable for pain upon movement of her cervix. Laboratory data include a white blood cell count of 18,000/mm3, serum glucose level of 145 mg/dL, and serum bicarbonate level of 21 mEq/dL. Her urinalysis is remarkable for 1+ white blood cells, 1+ glucose, and 1+ ketones. Which of the following is the most likely diagnosis?
A. Appendicitis
B. Diabetic ketoacidosis (DKA)
C. Gastroenteritis
D. Pelvic inflammatory disease (PID)
E. Right lower lobe pneumonia
8.4 A 16-year-old adolescent girl has enuresis, frequent urination, a white vaginal discharge, and a dark rash around her neck. She is greater than the 95th percentile for her age. Her serum glucose level is 250 mg/dL, and her urinalysis is positive for 2+ glucose but is otherwise negative. Which of the following is the most likely diagnosis?
A. Chemical vaginitis
B. Chlamydia cervicitis
C. Psoriasis
D. Type II diabetes
E. Urinary tract infection (UTI)
ANSWERS
8.1 A. The patient most likely has poor diabetes control. The hemoglobin A1C test, commonly used to follow glucose control, reflects the average glucose levels over the previous 2 or 3 months. The hemoglobin A1C goal for most diabetics is 6% to 9%. Levels greater than 12% suggest poor control, and levels of 9% to 12% represent fair control. In the Somogyi phenomenon, a patient has nocturnal hypoglycemic episodes manifested as night terrors, headaches, or early morning sweating and then presents a few hours later with hyperglycemia, ketonuria, and glucosuria. Counter-regulatory hormones, in response to the hypoglycemia, cause the hyperglycemia.
8.2 E. Up to 75% of newly diagnosed diabetics have a progressive decrease in the daily insulin requirement in the months after their diabetes diagnosis; a few patients temporarily require no insulin. This “honeymoon” period usually lasts a few months, and then an insulin requirement returns. Patients are told that the “honeymoon” period is not a cure and that they should expect a return to insulin requirement.
8.3 D. The patient likely has PID; glucosuria is a stress response to the infection and does not represent glucose metabolism problems. All of the options in the question can cause abdominal pain. Although diabetes mellitus is in the differential, DKA more likely presents with ketoacidosis (significantly decreased serum bicarbonate levels) and high serum glucose levels.
8.4 D. The description is of an obese adolescent female with candida vaginitis (the vaginal discharge) and acanthosis nigricans (the nuchal dark rash) consistent with type II diabetes. This condition is far more common in overweight children, especially those with a family history of the condition.
CLINICAL PEARLS
Diabetic ketoacidosis (DKA) is a medical emergency that can present with nonspecific signs of dehydration, polyuria, nausea, vomiting, and abdominal complaints. Hypothermia, hypotension, Kussmaul respirations, and acetone on the breath are also seen. A high index of suspicion is required to make the diagnosis, especially in the younger child.
Cerebral edema is a potentially life-threatening complication in diabetic ketoacidosis treatment presenting as headache, personality changes, vomiting, and decreased reflexes.
Electrolyte disturbances are common in diabetic ketoacidosis. Hypokalemia can occur during treatment if adequate sources are not provided. Bicarbonate administration usually is avoided except in extreme situations for a variety of physiologic reasons.
REFERENCES
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