Alexei Navalny, a strong critic of the Kremlin is at an increasing risk of kidney failure, an opposition allied medical trade union said on Saturday. 

Currently jailed in Russia, Navalny has been on a hunger strike for more than two weeks. His vision also started deteriorating after Navalny refused to eat prison food starting March 31 in protest of the alleged refusal of prison authorities to treat his severe leg and back pain, reported Reuters.  

A representative of the Doctors Alliance trade union, Alexandra Zakharova said, “His condition is indeed critical. We have seen the tests, and they are very, very bad,” she told Reuters. The trade union is regarded as opposition activists by Russian authorities. 

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Citing tests obtained from Navalny’s lawyer, she further said, “His potassium is high and he has other high readings which indicate that his kidneys may soon fail. This would lead to severe pathology and cardiac arrest may occur.” He has not been examined by the union. 

Dr Anastasia Vasilyeva, Navalny’s personal physician along with three other doctors wrote to the prison officials seeking permission to urgently see him. 

Posted on Twitter, Vasilyeva wrote, “We have been waiting for two days with concerns growing. No response thus far. Potassium in blood serum 7.1 mmol/L is both — kidney failure and severe heart-rhythm disturbances, i.e. ventricular fibrillation to the extent of cardiac arrest. The action must be taken immediately.”

Navalny is a strong critic of Russian President Vladimir Putin. 

On Friday, the 44-year-old said the prison authorities had threatened to put him in a straitjacket and force-feed him to make him the hunger strike, reported Reuters. 

Also Read: Alexei Navalny, jailed Vladimir Putin critic, losing sensation in hands, say his lawyers

Navalny was sentenced to two-and-a-half years in jail for parole violations which, according to him, are trumped up. He was arrested at the border in February when he returned from Germany where he was undergoing treatment for poisoning. 

The Russian prison officials said that Navalny had been offered proper treatment but he refused it and instead insisted on being treated by a doctor of his own choice from outside the prison. The ask was denied by them. 

Many prominent figures-directors, writers, actors including Salman Rushdie and JK Rowling penned down an open letter to Vladimir Putin to make sure Navalny receives the needed medical treatment.