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SAEM Clinical Images Series: Hey Doc, Can You Come Look at This Urine?

Genette Bergman, MD |


A 4-year-old male with no significant past medical history presents as a transfer from an outside hospital for suspected inhalation burn secondary to a house fire. The patient was home with his father and sibling when the apartment caught fire from a suspected flame in the kitchen. The patient was evacuated from the building by fire rescue after an unknown period of time. He was intubated at the outside hospital due to concern for inhalation injury. It is unknown if the patient sustained any trauma prior to extraction.

Vitals: T 98.1°F; BP 120/64; P 126; RR 29; O2 Sat 100% on vent

General: Intubated and sedated.

HENT: Singed hair and soot noted to nares, soot in mouth and secretions.

Cardiovascular: Regular rate and rhythm.

Lungs: CTABL, no wheezing or stridor.

GU: Normal appearing genitalia, no blood at meatus or from rectum, dark red urine noted in foley bag.

Skin: 0% TBSA burns, no obvious signs of trauma.


ABG at outside hospital: pH 7.0, carboxyhemoglobin 10, methemoglobin 3, lactate 3.7

Repeat ABG after transfer: pH 7.22, carboxyhemoglobin 1.7, methemoglobin 3.7, lactate 2.1

Hydroxocobalamin should be given in any case of suspected cyanide toxicity. House fires are the most common cause of cyanide toxicity in industrialized nations. Cyanide toxicity can also occur due to occupational exposures, medications, foods, or intentional ingestion. Cyanide inhibits the electron transport chain thus blocking aerobic metabolism, leading to hypoxia. Patients can present with altered mental status, hemodynamic instability, and dysrhythmias. Labs will be significant for lactic acidosis. Hydroxocobalamin should be given as soon as cyanide toxicity is suspected. Hydroxocobalamin works by chelating cyanide and forming cyanocobalamin which is renally excreted. Hydroxocobalamin is relatively safe and non-toxic but can cause transient hypertension. It also can cause a reddish discoloration of the urine, skin, and mucous membranes that can last up to several days. This is not harmful to the patient but can cause interference in urinalysis results.

Take-Home Points

  • Hydroxocobalamin is the antidote for cyanide toxicity and should be given as soon as possible in suspected cases.
  • Hydroxocobalamin binds cyanide to form cyanocobalamin, which is excreted in the urine.
  • Hydroxocobalamin is relatively safe but can cause transient hypertension and a red urine discoloration that can interfere with urinalysis results.

  • Cescon DW, Juurlink DN. Discoloration of skin and urine after treatment with hydroxocobalamin for cyanide poisoning. CMAJ. 2009 Jan 20;180(2):251. doi: 10.1503/cmaj.080727. PMID: 19153403; PMCID: PMC2621289.
  • Wong SL, Pudek M, Li D. Wine-Colored Plasma and Urine from Hydroxocobalamin Treatment. J Gen Intern Med. 2017 Feb;32(2):225-226. doi: 10.1007/s11606-016-3782-3. Epub 2016 Jun 23. PMID: 27338592; PMCID: PMC5264665.
  • Desai, S. & Su, Mark K. (2021). Cyanide Poisoning. In: UpToDate, Post TW (Ed), UpToDate,Waltham, MA. (Accessed on January 04, 2022.)
  • Lexicomp. (n.d.). Hydroxocobalamin (vitamin B12a supplement and cyanide antidote): Druginformation. UpToDate. Retrieved January 8, 2022,from https://www.uptodate.com/contents/hydroxocobalamin-vitamin-b12a-supplement-and-cyanide-antidote-drug-information

Author information

Genette Bergman, MD

Genette Bergman, MD

Resident Physician
Department of Emergency Medicine
UT Southwestern Medical Center

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