We’re going to explain why the urine of the protagonists of Society of the Snow is black

If there is one film on everyone’s lips right now it is Society of the Snow (original title: La sociedad de la nieve), which is directed by Juan Antonio Bayona and has received two Oscar nominations. The film is about Uruguayan Air Force Flight 571, the 1972 plane crash in the Andes involving a group of students and rugby players. It depicts the adverse conditions the survivors had to overcome until they were rescued 72 days after the crash.  

At one point in the movie, one of the protagonists urinates and the urine is black. Why does that happen? According to the experts consulted by Verificat, there is not only one cause, but multiple possible factors at play. Let us explain!

Changes in colour are a bad sign

Our urine should be light yellow. If this colour changes, it could be an indication that there is a health issue we need to get checked out, according to various websites that provide medical information, such as Medline or the consumer version of the MSD Manual. The causes range from having eaten beetroot or foods with colourants to the presence of tumours in the bladder or kidneys. In other words, the causes can vary quite a bit.  

In the case of the film, Esaú Fernández-Pascual, urologist at Lyx-Urología, told Verificat that one of the reasons could be “the dehydration they were subjected to”. The only thing the protagonists could drink was melted snow, so they may not have been meeting their daily water needs, which resulted in the liquid’s colour.

But that alone cannot explain it. Another possible cause for the colour of the urine we see in the film is myoglobinuria, an alteration caused by the excretion of myoglobin in urine. This protein is present in large quantities in skeletal and cardiac muscle, where it has the function of storing oxygen, and appears in the urine “in the case of polytrauma, when the muscle breaks down and the remnants of muscles (which, as we remember, contain myoglobin) are eliminated via the urine”, adds Fernández-Pascual.

This, in the case of the accident that takes place in the film, can have many causes, from the accident itself to the survival for over two months in the mountains.

Myoglobinuria indicates the destruction of the muscle

If some of the tissues that contain myoglobin – the skeletal and cardiac muscle – are damaged or ruptured, the protein is released into the blood where it will go into the urine, causing the typical black colour we see in the film.

Rupture can have many different causes, one of them being hypothermia. “When the temperature goes down, there is a constriction, a narrowing of the blood vessels that prevents the flow of oxygen to the muscles, and they break down”, Lluís Guirado Perich, kidney specialist and director of the Nephrology Service of Fundació Puigvert, explained to Verificat.

The second cause, the expert added, is trauma. “When there is such a serious accident, bones break, musculature breaks down and myoglobin is released”, which goes into the blood and is subsequently excreted via the urine.

The third cause is immobilisation. “It happens to people who have not moved, who have been buried for two or three days (…), which forces them to lean too heavily on certain muscular groups, and these muscles also break down”, Guirado Perich concluded.

Aside from all that, the expert pointed out other possible causes that could be at play in the situation: “Applying a tourniquet can prevent blood from reaching one part of the musculature, causing it to break down”, and burns “can also release myoglobin”.

So there were many possible causes of the myoglobinuria we see in the film. “[The colour] was probably somewhat exaggerated in the film”, Fernández-Pascual concluded. However, when your urine changes colour, it is best to consult a specialist.