December 2009
Feature Story

Karen Titus

When Kathleen McMonigal, MD, first moved to Houston in the early 1990s, her career took a turn for the wobbly. The community pathologist had left Maine when her husband earned a fellowship in space medicine at NASA.

Dr. McMonigal first took a part-time job at a local hospital. Then the hospital was taken over by another group. The question that ran through Dr. McMonigal’s head is one that has entered many pathologists’ minds in recent years: Now what am I going to do?

She applied for a job at NASA, where she was asked another hard question: Are you willing to do something else?

She was indeed. Which is how Dr. McMonigal ended up in her current job as director of clinical laboratories at Johnson Space Center.

It sounds glamorous. Dr. McMonigal’s everyday vocabulary now includes astronauts, International Space Station, microgravity, space walks, and “trip to Mars.”

But it’s also a small tale of transformation, just one of the many, many, tales that pathologists will be weaving, individually and as a specialty, while they figure out where to land in their 21st century practice of medicine.

Dr. McMonigal said “yes,” though somewhat cautiously, when NASA asked her if she’d take her career in a new direction back in 1997.

NASA had reservations of its own. “I was brought on as a pathology consultant,” recalls Dr. McMonigal. “They didn’t think they needed a full-time pathologist.”

Dr. McMonigal got her feet wet, so to speak, as one of NASA’s diving medical officers. Astronauts train in what is officially known as the Neutral Buoyancy Laboratory. Unofficially, it’s a very large swimming pool. Measuring 40 feet deep, 202 feet long, and 102 feet wide, it holds 6.2 million gallons of water. (By comparison, NASA notes that an Olympic-sized pool holds just over a quarter of a million gallons.)

“It’s a fascinating pool. You can fit the cargo bay of the space shuttle in crosswise,” says Dr. McMonigal. “When you see it, you can’t help but say, ‘Whoa!’ ” The pool has allowed crews to work on mockups of the space shuttle, as well as the space station and the Hubble Space Telescope, in preparation for space walks to perform the needed tasks on the space modules.

The point of the pool, of course, is that it simulates the weightlessness astronauts experience in space. The astronauts wear older space suits fitted with pockets filled with weights, which prevent them from either sinking to the bottom of the lab or popping to the surface—hence, neutral buoyancy. For every hour astronauts spend in space, they spend approximately 10 hours working in the pool.

Working as a diving medical officer was “quite a lot of fun,” says Dr. McMonigal, and seemingly a world apart from her previous roles in Maine and, before that, California.

But it wasn’t, really. “I would get asked pathology questions periodically, and I have to say, my training as a community pathologist came in handy on so many occasions,” she says. “And fortunately, it came in handy right at the beginning.”

In addition to training astronauts for space flights, NASA does considerable ground testing, trying to simulate a space flight environment from every which angle. In bed-rest experiments, for example, subjects will spend as many as 90 days lying in bed, with their bodies tilted slightly downward (head down and feet up), to help researchers study the effects of microgravity on the human body.

Microgravity is not the same as zero gravity, although the terms are often used interchangeably. In space, weightlessness occurs not because humans have broken free of Earth’s gravity; rather, in space, astronauts and their spacecraft are accelerating at equal rates. Gravity continues to exist in the spacecraft, but it lacks teeth, which is why anything not tied down will float away.

In other types of ground tests, NASA uses vacuum chambers and isolation chambers. Early in Dr. McMonigal’s career with the agency, researchers were using an isolation chamber as a human habitat to test hardware being developed for the space station.

One such experiment had individuals living in the chamber for 60 days; this would be followed by a 90-day study. Dr. McMonigal was brought in as a consultant for the 90-day effort, because one of the male subjects from the 60-day study had developed hypothyroidism. “It was an odd thing,” Dr. McMonigal says. “Females have a whole different threshold for thyroid disease. It’s 10 times more common in women than men. And I thought, ‘This is not quite right. This just ­doesn’t fit.’ ” As she investigated, Dr. McMonigal learned that NASA was using iodine to disinfect the water. “I said, ‘Really? How much iodine?’ ” A lot, as it turns out.

As Dr. McMonigal explains, normal daily iodine intake is 0.15 milligrams. The test subjects in the 60-day study were drinking daily two to four liters of water that had been treated with four to five mg/L of iodine. That, as Dr. McMonigal discovered, was the culprit. Moreover, this was the same water system being used in the space shuttle. Until then, it hadn’t been a problem, she suggested, because shuttle missions typically lasted 11 to 14 days. “You can get away with a lot of things for that time period.” Six months at the International Space Station would be a different story.

As a result of Dr. McMonigal’s work, NASA changed the potable water system on the space shuttle by adding a resin-type filter, and the water system for the International Space Station was redesigned as well.

“At that point, I wouldn’t say I was golden,” says Dr. McMonigal—and really, what pathologist would ever say that?—“but at least in some circles it was, ‘Well, she’s proven her value.’ ” Certainly not the first time a pathologist has been asked to do so, nor the last.

More inquiries followed, mostly related to clinical pathology, but occasionally she’d be asked to look at surgical pathology cases as well. After several years as a consultant, she was asked to take over the lab.

The ever-buoyant Dr. McMonigal characterizes this move as “great fun.” Up until she took over, the lab had been headed by only one other pathologist, who had left NASA; when he returned, in a different capacity, he asked Dr. McMonigal to step in. “So in the interim we hadn’t had a CAP pathologist running the lab,” she says.

Again, Dr. McMonigal’s background came in handy. NASA is, to be sure, unusual in some regards. Dr. McMonigal cheerfully reports she was pretty much given free reign to set things right at the lab, without having to fight competing interests for scarce funds. Yet her years in the trenches sharpened her approach. “I was imbued with all the constraints of a community hospital. You wouldn’t come in asking for something out of line, because you can’t justify it.” Thanks to NASA’s openhandedness, when she can justify her requests, they’re pretty much met. “With that, we’ve been able to update our equipment as need be, and have it be a full-service clinical laboratory.”

Its primary role is taking care of the astronauts. In many ways, Dr. McMonigal has remained a community pathologist. But it’s a small, elite community, whose members hardly ever get sick. “We take care of normal people,” she says. “All I have to do is see one lab value that’s out, and I think, ‘This isn’t right.’ ”

Their laboratory has two sets of reference ranges, one for astronauts and one for the occupational medicine clinic. The reference ranges for the astronauts are very tight. Those of the occupational medicine clinic more closely approximate the ranges seen in large reference labs. (She appreciates the expertise of the staff PhD biostatistician who establishes the reference ranges when instrument methodology changes and says NASA has discipline experts for nearly every area.) “We see tighter reference ranges in many tests—this is what very healthy people look like,” she says.

The lab also oversees care of the astronauts’ families and tracks retired astronauts in the Longitudinal Study of Astronaut Health. It does all occupational health testing for Johnson Space Center, and it runs the routine clinical tests for many of the center’s researchers, including screening of test subjects.

The pressure to keep astronauts healthy is intense. “They have to be healthy when we send them into space, because we have limited capabilities of taking care of them once they’re there.” Even antibiotics tend to degrade over time in space, Dr. McMonigal says.

She and her medical colleagues have worked to set and periodically revise the medical standards for astronaut selection. But even the healthiest individuals can develop medical problems, often as they age. If astronauts no longer meet the medical standards, Dr. McMonigal (who is the alternate chair of the aerospace medicine board) and her colleagues look to the waiver criteria they’ve developed. The implications are huge when the patient is involved in space flight. Will loss of capability lead to a catastrophe, to the individual, to the program, or to the loss of a mission?

Routine health care monitoring occurs once the astronauts are in space. The space station currently has an iStat on board, with controls and cartridges flown up periodically, and the Russians flew up a German chemistry analyzer, a Reflotron, though, for the most part, the equipment is kept in reserve. “When people are healthy, you don’t want to be bothering them with testing,” says Dr. McMonigal.

If fingersticks are bothersome on earth, they can be brutal in space. “We try to protect their fingers,” she says. Not only is it crucial to avoid infections, but there’s the difficulty of space walks and space suits. “You’re kind of like the Michelin man when you put one on,” she says. “There’s a lot of strenuous upper body work going on, and very detailed work with the hands, and we don’t want the pulp of the fingers to become tender.” That’s one reason why astronauts do a venipuncture whenever they need to draw blood in space.

The common jest that every astronaut is a million-dollar asset is actually true. So once astronauts are chosen, Dr. McMonigal and her colleagues will do everything in their power to keep them flying. Dr. McMonigal relishes this high-stakes challenge. “You’re using all the medicine you’ve ever learned, and then some.”

While she and her colleagues rely heavily on experts and the standards of branches of the armed forces, as well as their own experiences, they also have to balance a few unknowns. They may have an astronaut crew member in training who has a medical issue, or something that’s not quite optimal, and then have to extrapolate from there. How much training do they have left? Will a microgravity environment cause problems over and above what they might experience in a terrestrial environment?

The job has gotten easier over the years as physicians have acquired more knowledge and experience. Early on, she says, the answer would often be, “I don’t think we can take that chance. Now, we’re fixing folks up and flying them again. We’re so pleased we’re able to do that.”

But space is an extreme environment, and Dr. McMonigal admits she and her colleagues are only at the early stages of understanding the effects of space flight on the human body.

One of the biggest problems of longer flights is bone loss. “People are flying through the air from room to room—module to module—and they don’t use their lower bodies for anything other than navigation.” As a result, astronauts undergo bone loss at the rate of about one percent a month.

To counteract that (but insufficiently so) crew members will exercise two hours a day—hard enough on earth, but even harder when much of the astronaut’s time is taken up with running the space station itself. “The space station takes a lot of maintenance time,” Dr. McMonigal says. “When we had only three crew members up there, it took 2½ crew members to keep the place going.”

Then there’s the weightlessness. To run on the treadmill, the astronauts are held in by a harness-like contraption of bungee cords. They also use free weights and an exercycle. Even so, the astronauts lose bone and muscle.

Muscle returns fairly quickly. That’s not true of bone. And even when it does return, the quality may be different. Astronauts lose bone in the same way someone with osteoporosis does, in the bony trabeculae. But when astronauts return to earth, they tend to replace bone in the outer cortex. “Is that the same bone quality as what they lost?” she asks. “We don’t know. There are a lot of investigators working on that right now.”

They’re also looking at another effect of the microgravity environment: the tremendous fluid shift from the lower body to the head and neck. That’s why people in space appear to have full, round heads, a little like Peanuts characters, with puffy cheeks and squinched eyes. The side effects remain unknown, especially for astronauts who are in orbit for long periods. Will a six-month residence in space, for example, subject astronauts to increased intraocular pressure?

A couple years ago an ultrasound was flown up to the space station, enabling researchers to start mapping how organs shift in microgravity. The kidneys shift up a bit. The heart changes shape slightly. But no one knows, for example, if the heart undergoes cardiac atrophy—another area of intense research.

Dr. McMonigal has had plenty of input into these studies since becoming chair of the center’s institutional review board this year. (At Johnson Space Center, it’s known as the Committee for Protection of Human Subjects.) The group reviews the research taking place in space as well as ground-based testing.

One thing she’s most excited about is the biorepository. Up until two years ago, the space station lacked a freezer that could store clinical samples. Now there’s a MELFI (Minus Eighty Laboratory Freezer for ISS) freezer aboard, with three storage compartments—minus 80º C, minus 20º C, and refrigerated. Astronauts can now take and store samples, although, as with everything in space, that’s harder than it sounds. Astronauts draw their own blood. “Imagine having to draw blood in space, in microgravity, where everything is floating around and has to be Velcroed down,” Dr. McMonigal says.

Crew members take samples at regular intervals—up to five times while in orbit—and spin them using an onboard centrifuge. (They also have samples drawn at baseline and on return; they provide concurrent urine samples as well.) Dr. McMonigal has nothing but praise for the astronauts who’ve agreed to draw their samples and donate them to the biorepository. “They’re good sports. Most of them are not physicians, so they get trained to do this. And they have to set aside the time, and find all the specimen tubes that have been stashed away in various lockers—because everything has to be kept somewhere so it doesn’t go floating out—and then after they finish they have to spin their own samples down, and label them and put them in the freezers. It’s truly a do-it-yourself process.”

This is NASA’s first biological specimen repository. The repository won’t be accessed until 2017, when funding for the space station is set to expire. Then, says Dr. McMonigal, “All bets are off. We’re trying to plan for the eventuality that we won’t have a space station anymore. And it would be very nice to have an archive of samples available for future studies.” NASA also has active research protocols whereby investigators can obtain blood and urine samples for studies now, while the International Space Station is fully functioning and has six crew members in orbit at one time.

Again with an eye toward the future, Dr. McMonigal and her colleagues have begun doing more occupational surveillance, in part to learn the effects of radiation exposure on astronaut health—might they have accelerated aging, for example, or are they likely to have other medical conditions? “Radiation will be the most important issue we face if we ever send humans farther out into space,” she says. “There’s talk of sending them up to the moon and setting up colonies there.” Unless astronauts burrow underground, however, long-term colonies would be impossible to sustain, given the exposure to radiation. “We have the same issue with the dream of a trip to Mars.”

Pretty futuristic talk for someone who still retains a strong identity as a community pathologist, although Dr. McMonigal might not see it that way. Pathologists’ roles are always evolving, she says. The key, she says, is to be nimble. Before arriving in Houston, she never would have imagined herself at NASA, and she can’t imagine where she might go next. Her advice is simple: Stay as up to date as you can, in as many areas as you can. And be prepared to try something else. “Pathologists have to be willing to say ‘yes’ to taking on a new role. Because you never know where it’s going to lead.”

Dr. McMonigal doesn’t always say “yes.” When she was a diving medical officer, she didn’t want to dive. She’s never wanted to be a pilot, or an astronaut, or to be launched in­to space, even as a passenger. “For most people here, they would love to—it would be a dream come true,” she says. “Not me.”

Apparently even Dr. McMonigal has her limits. “I just love being on earth,” she says.