Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android. Learn more here!


A 1-year-old female is brought to the emergency department for lethargy and poor feeding. Parents noticed increased fussiness four days ago, with progressively worsening rhinorrhea and fever. She then developed emesis and diarrhea two days ago and has been refusing solids or liquids for the last 24 hours. She was previously healthy before this and takes no medications. She has a 10-year-old brother who recently recovered from similar symptoms, although the parents think his symptoms were milder. Temperature is 38 °C, blood pressure is 80/50 mmHg, pulse is 130/min, and respirations are 40/min. She is lethargic on exam. She cries without tears. Mucous membranes are dry. Cardiopulmonary exam is only notable for tachycardia and a II/VI systolic murmur. Capillary refill is 4 seconds. Dorsalis pedis pulses are 1+ bilaterally. Laboratory results are as follows:

  • Sodium 150 mEq/L

  • Potassium 3.7 mEq/L

  • Chloride 105 mEq/L

  • Bicarbonate 10 mEq/L

  • BUN 30 mg/dL

  • Creatinine 1 mg/dL

Initial management with which of the following is the next best step?

  1. 0.45% normal saline

  2. 0.9% normal saline

  3. Intravenous ceftriaxone

  4. Inhaled oseltamivir

What is a concise summary of this clinical scenario?

A 1-year-old girl is brought to the emergency department for lethargy and poor feeding for the last 24 hours in the setting of recent upper respiratory illness that started four days ago with a positive sick contact.

What is her physical exam notable for?

Lethargy and evidence of dehydration.

What are her vital signs notable for?

Fever, tachycardia, and hypotension.

What diagnoses do her vital signs suggest?

Dehydration or sepsis (Figure 6-1).


Systemic Inflammatory Response Syndrome (SIRS) and Sepsis. (Reproduced with permission from Grippi MA, Elias JA, Fishman JA et al. Fishman’s Pulmonary Diseases and Disorders, 5th ed. McGraw Hill, 2015.)

What are her labs notable for?

Elevated sodium, creatinine, BUN, and BUN/Cr ratio, with a decreased bicarbonate.

How do we interpret these labs?

Elevated sodium is likely related to her dehydration given her clinical history.

An elevated BUN/Cr ratio is suggestive of pre-renal kidney injury, likely related to her dehydration and/or likely sepsis.

What is her acid-base status?

Her decreased bicarbonate is concerning for metabolic acidosis. If we calculate her anion gap, we will find that she has an anion gap metabolic acidosis. Given the clinical history, this is likely a lactic acidosis in the setting of illness and dehydration. Because she has not eaten in 24 hours, there may also be an element of ketoacidosis (Figure 6-2).


Ketosis During Fasting State. During fasting, the pancreas stimulates ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.