Tuesday, 30 April 2019


Written by Natalia María García Simón | Aarón Izquierdo Bazaga | Aránzazu Martín García , Posted in Volumen10

Figure. Cobalamin structure is composed of six valence cobalt atom. Four of them form a covalent bond with nitrogen atoms. The fifth valence forms a bond with the bencimidazole nitrogen. The sixth valence forms a bond with various anionic groups: A) hidroxicobalamin with hydroxyl group (OH-) and B) cianocobalamin with cyanide group (CN-). C) Reddish coloration of serum, characteristic of treatment with hydroxycobalamin in the patient’s sample.
72-year-old woman was admitted in ICU ought to carbon monoxide poisoning. She presented symptoms of bewilderment and general malaise and related being all day with a running coal stove. Cyanide co-poisoning was suspected after finding carboxyhemoglobin, troponin and lactate elevated in the analysis made at admission. Treatment was based on oxygen therapy, saline and hidroxycobalamin.

Hidroxycobalamin is used as an antidote for cyanide poisoning. Cyanide is a highly dangerous substance due to its binding with cytochrome oxidase enzyme, which is essential for the cellular energy metabolism. Once the enzyme binds to cyanide, its function is annulled causing cell death. The most serious damage tends to be at heart level and the nervous system. Several studies have shown that the greater the tissue damage, the worse the prognostic is, with higher mortality.

Such poisoning can happen because of smoke exposure as in the present case. It can also occur when breathing or swallowing cyanide as well as skin and/or mucosae contact.

This antidote reacts with the cyanide in the organism resulting in cyanocobalamin, a non-poisonous and soluble compound that is easily excreted in urine.

Hidroxycobalamin has an intense red colour, which gives patients reddish skin and mucosae up until 15 days after treatment. This colouring is also presented in blood and urine samples that can be mistaken as haemolysis or haematuria.  

On the one hand, colouring may interfere in biochemistry assays such as bilirubin, creatinine, amylase, alanine y aspartate aminotransferases (ALT, AST), iron, phosphor and creatine kinase (CK), depending on the analyser used. These interferes can lead to falsely high or low results. This can lead to a misinterpretation of the lab test if the cause of the redness is not known to be a consequence of interference due to treatment with hidroxycobalamin instead of haemolysis. Therefore, this can lead to a wrong interpretation of the actual status of the patient as well as their evolution.  

In the present case, we ruled out serum haemolysis by measuring the levels of haemoglobin in a spectrophotometric analyser, after observing a reddish serum colour as in the figure. No urine sample was received.  

Serum colouring gradually faded out until the fourth day. The patient’s progress was favourable, probably because no serious organ failures were presented. On the fifth day, the patient was discharged.

  1. (2019). [online] Available at: [Accessed 7 Feb. 2019].
  2. Fueyo L, Robles J, Aguilar I, Yáñez AM, Socias M, Parera M. Hemolysis index to detect degree of hydroxocobalamin interference with common laboratory tests. J Clin Lab Anal. 2017; 31(5).
  3. Wong SL, Pudek M, Li D. Wine-Colored Plasma and Urine from Hydroxocobalamin Treatment. J Gen Intern Med. 2017; 32(2):225-6.
  4. Fifi K, de Rancher MA, Carteret CE, Maquart FX, Oudart JB. Unexpected Case of Bright Pink-Colored Plasma. Clin Chem. 2016; 62(8):1162-3.

Leave a comment

Please login to leave a comment.