(CNN) - What the world knows about President Donald Trump's general health is not much as of now -- and what the public learns about his health after a medical exam on Friday might not be much, either.
Trump, 71, is scheduled to undergo his first formal physical exam since taking office.
"We'll only learn what he wants us to know," said Arthur Caplan, a professor and founding head of the Division of Medical Ethics at NYU Langone Health in New York.
"A physical is forward-looking and almost, really, an examination of your biochemistry. We're going to look at your blood and your urine, and we're going to take a look at your heart electronically," said Caplan, who was one of 75 health professionals who signed a letter urging Trump's doctor to evaluate his neurological health (PDF).
Presidents historically will "release general information on things like cholesterol, is there any problem with emerging diabetes or the president's heart. ... It won't solve or settle any of the controversies about his competence," he said. "The president has the same right to privacy as you or I would if we went to get a physical. No one has the right to know what the results are. There's no legislation, there's no requirement that he tell us anything."
Trump's physical will be performed at the Walter Reed National Military Medical Center in Maryland and conducted by the White House physician, Dr. Ronny Jackson, who also performed President Barack Obama's last several physicals while he was in office.
The White House has said it will provide a readout of the exam on Tuesday, but until then, here is what we know about Trump's health.
Trump's weight and cholesterol
Dr. Harold Bornstein, the president's personal physician at the time, released a letter in 2016 detailing Trump's key stats, including his body mass index, blood pressure and even testosterone level.
The letter noted that at 6-foot-3 and 236 pounds, Trump had a body mass index of 29.5, which made him overweight, according to the National Institutes of Health's online BMI calculator.
"Overweight and obesity increase the risk for diabetes, heart disease and high cholesterol," said Dr. Ranit Mishori, professor of family medicine at Georgetown University School of Medicine who was not involved in the president's care.
"I would focus on lifestyle modifications, diet changes and exercise," she said. "Come up with a plan for incorporating exercise and/or dietary changes into the daily routine, recommend a healthy diet -- Mediterranean, lots of fruits, and vegetables, little red meat -- and likely perform a blood test for diabetes, in addition to cholesterol levels."
Trump had a total cholesterol level of 169, "good" HDL cholesterol of 63, "bad" LDL cholesterol of 94 and blood pressure of 116/70, according to the letter.
Blood pressure levels less than 120/80 are considered "normal."
Trump's blood and heart health
The letter also indicated that Trump's blood sugar level was 99 milligrams per deciliter, and his triglycerides, which are a type of fat found in the blood, were 61 mg/dL. For a fasting blood glucose test, which measures sugar, a level between 70 and 100 mg/dL would be considered "normal."
Trump takes a statin, called rosuvastatin, to treat high cholesterol and triglyceride levels, and he takes a low-dose aspirin, according to the doctor's letter.
The letter also indicated that Trump was screened for prostate cancer, which resulted in a low score, meaning there was no evidence of cancer. He had a colonoscopy in 2013 and a transthoracic echocardiogram to examine his heart in 2014. Both tests appeared to be normal.
The letter also mentioned that Trump's testosterone level was 441.6.
A testosterone test measures the amount of the male hormone in the blood, and normal measurements for these tests typically are 300 to 1,000 nanograms per deciliter among men and 15 to 70 among women, according to the US National Library of Medicine.
"From the scientific perspective, it would be interesting to see what kinds of tests he's had," Mishori said. "My guess is that he'll have what's called a VIP or 'executive' physical: a very thorough and lengthy affair with multiple specialists" and many tests, such as EKG, carotid artery ultrasound, urinary test, PSA test and more.
Trump's mental health
That 2016 doctor's letter noted that "Mr. Trump is in excellent physical health."
Yet since taking office, Trump's mental health has become a topic of public interest.
A review of the past five presidents' physical exams shows only brief mentions of mental health, and none included a readout of mental health tests.
"Although cognitive screening is not recommended in every individual older than 65 years because of a current lack of evidence for or against screening, the US Preventive Services Task Force advises clinicians to look for early signs or symptoms of cognitive impairment, such as problems with memory or language," Mishori said.
"They are not generally considered routine parts of the physical. The task of recognizing changes in memory, thinking and other cognitive functions and distinguishing whether such symptoms are due to normal aging or are signs of early dementia is not an easy one," she said.
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