(CNN) Organ transplants performed in the United States reached a record high during 2016, for the fourth year in a row, according to preliminary data from the United Network for Organ Sharing .

During 2016, there were 33,606 transplants, an 8.5% increase over 2015 and up 19.8% since 2012. This growth can be mostly attributed to an expanding number of deceased donors.

About 82% (or 27,628) of the transplants involved organs from deceased donors, who often provide multiple organs. The remaining 18% (or 5,978) were performed with organs from living donors.

There have been fewer disqualifications of deceased donations over time, explained Dr. David Klassen, chief medical officer of the organ sharing network, which serves under federal contract and brings together medical professionals, transplant recipients and donor families.

No uniform criteria for donations or enforced guidelines exist across the procurement and donation network, Klassen said. Instead, donation and transplant professionals use their best judgment to evaluate whether each donated organ will be safe for a patient, such as whether an elderly deceased adult would be a safe donor.

Another source of donor organs is rooted in the opioid epidemic sweeping the nation.

"The number of donors who died of overdoses increased over the past year," Klassen said. The percentage of donors who have died from overdoses is approaching 25% of the donor population in some parts of the country, he said.

Increased donation as a result of drug overdoses is not a trend anyone wants to see continue, he said but there's still potential for increasing the number of donors.

"The transplant community is pretty energized in terms of trying to make use of all donors of potential," Klassen said.

One energized member of the community is the New England Organ Bank, which works with over 150 hospitals.

"In many ways, our results in 2016 mirrored those nationally," said Alexandra Glazier, the organ bank's president and CEO. "We achieved a 19% increase in organ donation." She said this was achieved by "participating in national efforts through organizations like Donate Life America " while taking the lead in finding donors.

"In New England, we work closely with the motor vehicle departments in all six states to make it fast and easy for individuals getting or renewing licenses to register as organ and tissue donors," Glazier said. "Another part of our effort is to provide information and support to families of unregistered individuals who have died to offer them the option to make the donation decision."

Across the nation, kidneys are the most commonly demanded and transplanted organ every year, partly because dialysis can prolong the life of people waiting for this organ. In 2016 , a total of 19,057 kidney transplants occurred, followed by 7,841 liver transplants, 3,191 heart transplants and 2,327 lung transplants.

Currently, 119,053 people are waiting for a life-saving organ in the United States.

One recipient's story

One grateful recipient, Jay Monahan, 28, received a deceased donor kidney transplant in October.

MPGN, as it is commonly called, is one of a group of conditions in which the immune system damages the kidney. Monahan, a native of Bedford, Massachusetts, was diagnosed at age 9 with membranoproliferative glomerulonephritis MPGN, as it is commonly called, is one of a group of conditions in which the immune system damages the kidney.

For most patients, the condition can be treated and will continue unchanged for years, though it must be routinely monitored. For some, the condition goes away on its own. However, for other patients, it leads to kidney failure.

"My kidneys failed very slowly over the course of about 10 years," Monahan said. "I started to get sick when I was a junior in high school. It was fatigue, mostly; I would have days when I couldn't even physically get out of bed."

Though he finished high school, "that was it," Monahan said. "I couldn't go to college. I was too sick."

"I had a transplant when I was 21 from my mom, which only lasted two years, and then I was on dialysis for five years until I got my second transplant in October."

One recent, though small-scale, study found a The failure of his first kidney was not entirely unexpected, since close to half the people with MPGN see the disease reoccur in the transplanted kidney within five years.One recent, though small-scale, study found a 45% disease recurrence rate post-transplant.

When his first donated organ began to fail, Monahan entered a study for an off-label use of Soliris , a drug that blocks the immune system from attacking the kidney. It seemed to be working, but then the study ended. Within a month, his transplant failed, and he began dialysis while waiting for a second kidney.

"Dialysis was very difficult," Monahan said. For the first four years, he did peritoneal dialysis , in which wastes are removed from the blood by a cleansing fluid. The fluid is washed into and out of a patient's belly in cycles, with the inside lining of the belly acting as a natural filter.

"I was able to do that at home, and that was every day -- but that wasn't as bad, because I was able to do it while I slept," he said. "And then that eventually stopped working, and I had to switch to hemodialysis for the last eight months, and that was three days a week for 3½ hours."

In hemodialysis , blood is pumped out of a patient's body to an artificial kidney machine and then returned.

After his new transplant, Monahan is back on Soliris, and this time he will stay on it "indefinitely," he said.

Not only are his doctors more hopeful, his health has been pretty good.

"I went back to work within three weeks after the transplant," said Monahan, an ice hockey referee.

"I'm not sure who my donor is, but I'm going to try to find out within a few months," he said. He plans to contact the organization that procured his kidney, the New England Organ Bank , which facilitates correspondence between donor families and organ recipients.

Though at first the exchange of notes is anonymous, "when both recipients and donor families agree, direct contact information can be shared," Glazier said. She added that in some cases, patients and donor families do meet.

Though unsure what he will say, Monahan hopes to express his gratitude for the gift. And he's still thankful for his mother's generous donation; her health continues to be "great," even eight years since the procedure, he said.

"It means a lot that my mom gave me a kidney. I mean, she says it's not a big deal because any parent would do that for a child, but I still think it's a big deal," Monahan said.

Going forward

The increase in life-saving organ transplants is due in part to improvements made throughout the network, which includes individual organ banks, officially known as organ procurement organizations, and hospitals where transplant surgeries occur.

"To make it all work takes coordinated effort," Klassen said.

Currently, 58 organ banks of varying size and geographic range operate across the nation, all working toward the same goal.

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"One of the areas we're very interested in is looking at the regulatory and oversight structure that surrounds transplant programs," Klassen said. Both the organ donation network and the government itself are "trying to remove any disincentives that programs have for being able to maximize donor potential." He admits, though, that "those changes could be kind of slow to come."

One such disincentive is that organ procurement organizations are evaluated on various metrics that may be a bit too stringent. One of these metrics is patient and graft survival, said Klassen. Currently, over 95% of patients and about 95% or slightly fewer of transplanted kidneys survive.

"The results are really excellent," Klassen said. "But there's a perception that the standards are so tight that, in fact, programs become overly caution to the disadvantage of people on the waiting list."