A CASE OF BLUES

Document Type

Conference Proceeding

Publication Date

6-17-2022

Publication Title

J Gen Intern Med

Abstract

CASE: A 28-year-old female with a past medical history of scleroderma and type 1 diabetes presented to the emergency department with blue lips and shortness of breath. The patient initially had three days of dysuria. She started taking over the counter phenazopyridine for urinary pain. She took a total of twelve doses within two days. On the morning of presentation, she noticed that her fingertips and lips were becoming blue and she was feeling short of breath. She was afebrile, tachycardic (HR 116), tachypneic (RR 31), hypertensive (BP 137/93), and hypoxic (SpO2 85%) on room air. On physical exam, her heart was regular, tachycardic, and without murmur. Lungs were clear to auscultation bilaterally. She had central cyanosis involving the lips as well as peripheral cyanosis involving the fingers. She was alert and oriented to person, place, and time. Labs showed an elevated methemoglobin level of 21%, acute kidney injury (creatinine 1.06 elevated from 0.55 previously), normal serum bicarbonate (22), normal hemoglobin level (14.6), and lactate 1.3. An arterial blood gas demonstrated a pH of 7.46, PCO2 33.1, O2 Sat 98.1, and PO2 416. Urinalysis showed positive nitrite, negative leukocyte esterase, and rare bacteria. Urine culture did not demonstrate any growth. Chest x-ray and computed tomography pulmonary angiogram imaging were negative for an acute process. She initially required 100% non-rebreather to maintain SpO2 >88%. Methylene blue (1mg/kg) was administered with rapid improvement in cyanosis, dyspnea, and oxygen requirements. The acute kidney injury resolved with fluids. IMPACT/DISCUSSION: Phenazopyridine is a commonly used over-thecounter urinary analgesic available throughout the United States.1 Its side effects include headache, dizziness, and abdominal cramps (1-10%) with <1% of side effects being acute renal failure, methemoglobinemia, and hemolytic anemia.2 Phenazopyridine-induced methemoglobinemia is a rare side effect with very few case reports.3 We present a case of phenazopyridineinduced methemoglobinemia in a young female. This case highlights the importance of a thorough history and physical exam in diagnosing a lifethreatening emergency efficiently while avoiding unnecessary testing. CONCLUSION: Although rare, methemoglobinemia is a serious and lifethreatening side effect of over-the-counter medications including phenazopyridine. Common causes of hypoxia and cyanosis like pulmonary embolism should still be excluded. However, methemoglobin levels should be obtained when suspicion is high, and patients should be treated with methylene blue when the diagnosis has been made.

Volume

37

First Page

S384

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