How did Doug Blawell Die from Bravo Workout?

Yes, what a loss. Doug was a terrific person. Cheo, the guy who was getting the blood transfusions, was his ex who was awaiting a kidney transplant. As for Doug, he passed away suddenly, and here is the Wikipedia article:

At the time of his death in 2007 he was 44 years old. According to The Advocate, Blasdell died unexpectedly after being rushed to the hospital. No official report has been released on the cause of death. According to reports, he was hospitalized in December and he went into a coma not long after New Years. While he was undergoing chemotherapy for a brain tumor, reports have stated he was in remission at the time of his death. [6][7]

On April 10th, Bravo released the third episode into the second season of its series "Workout." Doug was dealing with the medical situation of his ex-lover, who was undergoing kidney complications as well. He was assisting in helping him with building up enough strength to undergo a kidney transplant.

The day before Doug's 44th birthday, Doug and his ex-partner of 15 years, Cheo, were working out at SkySport. In cutscenes, Doug talked about how other members of his family did not live to see 43 and that he was going to celebrate his 44th birthday, a momentous occasion for him. He coincidently states this will be the last birthday party that he will celebrate.

During his birthday party and Cheo's blood treatment, Doug was noticeably sick onscreen, coughing almost nonstop. Finally after his party, he was "M.I.A.," in a very concerned Jackie's words, because he had not come into the spa for a week and not answering phone calls. Jackie did not realize how serious everything was until she finally got a call from Cheo saying that Doug had a very severe flu and was admitted to the hospital, and was so dehydrated that his kidneys shut down to the point where he was put into a chemically-induced coma.

Jackie announced the news of his illness to her trainers, some of whom were visibly upset and saddened by the news. Despite a disagreement between him and fellow openly gay trainer Jesse Brune (which was settled on Doug's birthday), Doug was well liked and respected by his fellow trainers and his SkySport clients, including singer Jody Watley. Trainer Brian Peeler broke the news of Doug's death to his fellow trainers.

On February 9th, 2007, Entertainment Weekly reported kidney failure as the cause of death. [8]

In an April Blog on BravoTv's website, Brian Peeler announced that Doug had been undergoing chemotherapy for lymphoma. Doug became ill with salmonella poisoning after his birthday and later developed a staph infection from the shunt in his neck that would ultimately cause his liver to also shut down and contribute to his death. [9] Brian further discusses the circumstances surrounding Doug's death in a recent interview with AfterElton.com.

he got a severe case of the flu and his kidneys shut down. He had to have dialysis all the time and eventually died. It was very sad.