A two-page letter from Hillary Clinton's doctor a year ago, declaring the former first lady, senator and secretary of state "fit to serve" as president has done little to quell doubts about her health amid a gruelling campaign.

Photos of the Democratic presidential nominee being helped up stairs, frequent coughing bouts on the campaign trail and rumors that a 2012 concussion was worse than revealed have made the 68-year old's fitness a campaign issue.

“Hillary Clinton lacks the judgement, the temperament and the moral character to lead this nation," Donald Trump said in a recent foreign policy speech. "Importantly, she also lacks the mental and physical stamina to take on ISIS, and all the many adversaries we face – not only in terrorism, but in trade and every other challenge we must confront to turn this country around.”

Hill steps

Hillary Clinton lost her balance briefly as she arrived for a tour of a home for ex-offenders and substance abusers in North Charleston, S.C., on Feb. 24, 2016. (Reuters)

Clinton’s health has been a matter of scrutiny since the concussion she suffered while serving as secretary of state. While being evaluated at New York-Presbyterian Hospital, doctors discovered a blood clot inside a vein in her head and prescribed blood thinners, she told ABC News’ Diane Sawyer in 2014.

In part to quash speculation about Clinton’s health, the campaign released a summary of her medical records last summer.

In the July 28, 2015 letter,  Dr. Lisa Bardack, an internist in Mount Kisco, N.Y., described Clinton “as a healthy 67-year-old female whose current medical conditions include hypothyroidism and seasonal pollen allergies.”

Unlike 2008 Republican presidential candidate John McCain who invited reporters to review the full 1,173 pages of his medical records, Clinton released only a summary of her past issues, including an elbow fracture in 2009 and several episodes of deep vein thrombosis.

Clinton’s chief strategist Joel Benenson said the campaign has no plans to release more detailed records, but his position is at odds with many Americans.

A new Rasmussen Reports survey found that 59 percent of voters believe all major presidential candidates should release at least their most recent medical records to the public. That figure is up from 38 percent of Americans in May 2014, when questions about Clinton's health were first being raised.

Thirty percent don’t think candidates should have to release their recent medical records and 11 percent were undecided.

The people may want to see more medical records, but the Clinton campaign just sees right-wing conspiracy. A campaign spokeswoman blamed the health controversy on Roger Stone, a longtime conservative policeal operative who had a formal role as a Trump adviser until he was fired a year ago. Still an unabashed supporter of Trump, Stone is still working to get him elected, say critics.

“Donald Trump is simply parroting lies based on fabricated documents promoted by Roger Stone and his right-wing allies," said campaign communications director Jennifer Palmieri. "Hillary Clinton has released a detailed medical record showing her to be in excellent health plus her personal tax returns since 1977, while Trump has failed to provide the public with the most basic financial information disclosed by every major candidate in the last 40 years.”

Requests for comment from the Clinton and Trump campaigns were not answered. Bardack’s office declined to comment.

“I think the questions being raised are legitimate given that it impacts who leads our nation," said Dr. Jan Orient, executive director of the Association of American Physicians and Surgeons. "As a physician, you cannot help but to ask questions. But given that our information is limited, it would be wrong for any physician to diagnose someone without seeing them themselves.”

Orient said she has received both positive and negative responses to her recent column on the Association’s blog which asked whether Clinton is “medically unfit” to serve as president.

Television personality Dr. Drew Pinsky told KABC radio this week that he was concerned about the “1950s level of care” that Clinton was receiving and not as much about her actual health.

“It just seems like she’s getting care from somebody that she met in Arkansas when she was a kid,” he added.

While agreeing that a candidate’s health is a serious issue for voters to consider, one Trump advisor warned against either side diagnosing the physical or mental health of the candidates.

“I would be very cautious and would recommend the doctors for professional reasons to be very cautious when deciding you are going to analyze people,” said former Speaker of the House Newt Gingrich on Fox & Friends.