A 70-year-old woman is brought to the emergency department by her daughter due to lethargy. The patient has a history of mild cognitive impairment but lives alone and is able to perform daily activities by herself. She experienced a minor febrile illness with upper respiratory symptoms several days ago, and her primary care physician advised symptomatic treatment. Since then, the patient has reported generalized weakness and decreased appetite to the daughter. Today, the patient did not answer her phone and the daughter found her lethargic and confused. The patient takes no medications and does not use tobacco or alcohol. Temperature is 37.2 C (99 F) , blood pressure is 92/50 mm Hg, pulse is 110/min, and respirations are 18/min. Physical examination shows dry oral mucosa. Lung auscultation reveals right-sided bronchial breath sounds and crackles. Laboratory results are as follows: Chest radiography reveals a right lower lobe consolidation. Which of the following additional findings is most likely in this patient?

Question

A 70-year-old woman is brought to the emergency department by her daughter due to lethargy. The patient has a history of mild cognitive impairment but lives alone and is able to perform daily activities by herself. She experienced a minor febrile illness with upper respiratory symptoms several days ago, and her primary care physician advised symptomatic treatment. Since then, the patient has reported generalized weakness and decreased appetite to the daughter. Today, the patient did not answer her phone and the daughter found her lethargic and confused. The patient takes no medications and does not use tobacco or alcohol. Temperature is 37.2 C (99 F) , blood pressure is 92/50 mm Hg, pulse is 110/min, and respirations are 18/min. Physical examination shows dry oral mucosa. Lung auscultation reveals right-sided bronchial breath sounds and crackles. Laboratory results are as follows:

Chest radiography reveals a right lower lobe consolidation. Which of the following additional findings is most likely in this patient?

Quizplus · Accepted Answer

11ec25c8_d4f1_b5fd_bc81_6bc8e851bb2e_MD0003_00 This patient's clinical presentation (altered mental status, tachycardia, hypotension, leukocytosis, evidence of right lower lobe consolidation on chest x-ray) is consistent with sepsis due to community-acquired pneumonia. Sepsis leads to peripheral vasodilation (hypotension) and intravascular volume depletion (due to vascular leakage); manifestations of volume depletion in this patient include decreased appetite/poor oral intake, dry mucous membranes, and hypernatremia. The combined effects of sepsis and volume depletion suggest that this patient has a prerenal acute kidney injury (AKI) due to decreased renal perfusion. Renal hypoperfusion leads to a decrease in glomerular filtration rate and a consequent increase in serum creatinine. Activation of the renin-angiotensin-aldosterone system results in increased sodium reabsorption by the kidneys, leading to a urinary sodium of <20 mEq/L and a low fractional excretion of sodium (<1%). Urea passively follows the reabsorption of sodium and water, resulting in an elevated blood urea nitrogen (BUN)/creatinine ratio (>20:1). There is no intrinsic kidney damage or infection in pure prerenal AKI; therefore, urine sediment is bland (eg, acellular, no urinary red blood cells or white blood cells [WBCs]). renin-angiotensin-aldosterone system In addition to the treatment of the underlying disorder (eg, antibiotics for pneumonia), patients with prerenal AKI require volume resuscitation with intravenous crystalloids as soon as possible to restore adequate renal perfusion. (Choices B and C) If renal hypoperfusion persists, renal ischemia will lead to acute tubular necrosis (ATN), which is characterized by muddy brown granular urinary casts and an elevated urinary sodium (>20 mEq/L) due to impaired reabsorption of sodium by the injured tubules. Additionally, contrast-induced ATN can result in a low urine sodium (<20 mEq/L). However, ATN typically results in a BUN/creatinine ratio of 10-15:1. Occasional urinary WBCs may be seen due to inflammation; however, high levels (>30/hpf) may suggest a urinary tract infection. (Choices D and E) Red blood cell casts are commonly seen in glomerulonephritis (eg, poststreptococcal glomerulonephritis), and glomerular inflammation can result in a mild elevation of urinary WBCs. However, glomerulonephritis typically results in hematuria and hypertension. Additionally, the urine sodium is typically low (<20 mEq/L). Very high urinary sodium levels are often seen in the syndrome of inappropriate antidiuretic hormone (SIADH) or in patients on diuretics. Educational objective: Sepsis leads to hypotension and intravascular volume depletion and is a common cause of prerenal acute kidney injury (AKI). Prerenal AKI is characterized by low urinary sodium (<20 mEq/L), low fractional excretion of sodium (<1%), and elevated blood urea nitrogen/creatine ratio (>20:1). Urine sediment is bland. References: Sepsis-associated acute kidney injury. (http://www.ncbi.nlm.nih.gov/pubmed/25795495)

A 70-Year-Old Woman Is Brought to the Emergency Department by Her