The 1-year-old lying on the exam room table was quiet. That troubled me. Generally, 1-year-olds do not take kindly to pediatricians bearing down on them with lights, tongue depressors and stethoscopes. For two days the boy had suffered diarrhea, vomiting and fever. Everything he drank came back up, his mother told me. "Leche, agua, jugos." Milk, water, juice. What didn't come up, came out the other end.

He did not protest as I examined him.

His mother was tired and worried, a handsome woman with mestizo features, blue jeans and sneakers. She had a 2-year-old in a stroller with her and a 4-year-old at home. She spoke no English and had no health insurance. Most days she worked as a domestic while her husband took care of the children. They had come from El Salvador five years ago looking for a better life in Washington. The children were born in the United States and are citizens, but their parents are still "undocumented," making them fugitives in the land of their children.

The boy showed signs of dehydration but his temperature was normal and he readily drank and kept down 2 ounces of electrolyte solution, a preparation of sugar, water and salt designed for infants with diarrhea and vomiting. I judged him well enough to go home with instructions to his mother to offer him small quantities of fluid on an hourly basis and to return the next day or sooner if his diarrhea got worse. We gave the mother a bottle of Tylenol and the name of a nearby pharmacy with the best buy on electrolyte solution. She bundled her two children into the stroller and left.

This encounter took place recently at the Upper Cardozo Community Health Center in Northwest Washington, where I work part-time as a staff pediatrician. The center, built in 1972 when federal community health center money was plentiful, is a massive building that resembles nothing so much as a above ground bomb shelter. The Center, located at 14th and Irving Streets NW, sits next to a gargantuan excavation, criss-crossed by girders and pipes that will someday be the Cardozo stop on the Green Line. Inside, the center is spacious but dilapidated, a veteran of hundreds of thousands of patient visits set against ever-diminishing public funding. After many years of mismanagement, the clinic was taken over in January of 1996 by the District of Columbia's Health Care for the Homeless organization that has produced a total turnaround in both the spirit and the efficiency of the health center. One hundred and fifty patients a day visit the center for a variety of medical, nutritional and social services. All of them are poor, three-quarters are uninsured and their languages include English, Spanish, Vietnamese, Arabic, Cambodian and Kurdish.

For me, the entire scene was a throwback -- clinically, ethnically, environmentally. Some 25 years ago, I did my residency in pediatrics in the Bronx, N.Y. I worked in New York City hospitals where most of the patients were Puerto Rican; they had little work and less money. Spanish was the language of the clinic and diarrhea and dehydration were common problems. "Documentation" was not an issue for Puerto Ricans, but the pediatric diseases of poverty such as lead poisoning, the effects of being born prematurely, iron deficiency anemia and asthma were much with us then, as they are now.

Those experiences early in my medical career propelled me down a path that eventually took me away from patient care. I joined the National Health Service Corps (a federal program that sends doctors to underserved areas) and went to New Mexico to work in a community clinic. After several years there, I moved to Washington to help run the program and embark on what proved to be 20 years of practicing administrative medicine.

As much as I enjoyed my work in the health policy arena, I never meant to relinquish my role as a clinician; I never intended to stop laying on hands. So it was with a mixture of anticipation and trepidation that a year ago, after almost 20 years out of practice, I decided to retrain in pediatrics for the purpose of reclaiming my place as a clinician. The general pediatrics department at the Children's National Medical Center took me on as a "mature" resident, and I worked in a variety of outpatient and community-based settings. I also made rounds in the hospital where teams of physicians manage acutely ill children and teach medical students and residents inpatient care.

I found that old skills and knowledge reappeared pleasingly quickly, while new knowledge -- all the changes in treatments, the use of new drugs and diagnostic procedures -- took a bit longer to find a home in my crowded brain. The senior staff at Children's Hospital was extremely generous with their time and teaching -- empathizing, I believe, with my mission. My relationship with the residents was a bit more complicated, because they were never sure whether I was their peer, their teacher or their student -- all of which I was, at one time or another. * * *

I first saw her climbing into a surplus kiddie wheelchair at the back of the clinic. She was only 5, but she carried herself with a confidence and poise that made her seem much older. She knew her way around the clinic, knew all the staff by name, and seemed as comfortable in this setting as she might have been in her kindergarten class. The clinic, in this case, was the HIV clinic at Children's Hospital, and the little girl had AIDS.

Her comfort level was hard earned from a lifetime of hospitalizations, clinic visits, medications, bloodletting and the general invasion of her childhood. In an ironic but not uncommon intergenerational twist of the disease, her mother was not yet sick although she also had the human immunodeficiency virus (HIV) that causes AIDS and had seeded her daughter with the virus during pregnancy. The girl's disease had erupted early in her life, making her a constant client of the medical system, an intimate of the HIV clinic and its staff.

The staff, for its part, was fabulous. Pediatricians, infectious disease experts, nurse practitioners and nurses dealt not only with the constantly changing and enormously complex clinical science surrounding HIV treatment, but also modulated their therapies to protect their small patients as much as possible from the invasiveness and pain of the many treatments. The social workers who coped with schools and insurance and, at times, dying and death, were as much a part of the team as the physicians and nurse practitioners.

My young patient succeeded in launching the wheelchair and propelling it out to the front of the clinic, where she and another child added it to a "fort" they were designing in the waiting room. Her body was thin, making her eyes look oversized. She had bandages on both arms where blood had been drawn. Otherwise, she was a vivacious child, building her fort, extracting pleasure from life, moment to moment.

HIV was not on the scene when I last practiced medicine. Today its shadow is everywhere. No blood is drawn without gloves; blood and blood products are used with great caution. Weight loss, coughs, swollen lymph nodes and a dozen other symptoms bring AIDS to the mind of the examining physician. The clinical and financial burden of treating AIDS presents a challenge to every urban medical center. Infectious disease is back on the agenda of every clinician in a way that could not have been imagined 20 years ago.

AZT, DDI and protease inhibitors, among other medications, are all part of a new and rapidly changing frontier of interventions that are extending the lives of people infected with HIV. Infected mothers are now treated with AZT, significantly decreasing the rate of infection in their children. The little girl in the wheelchair perseveres thanks to this new generation of treatments that do not cure AIDS but do prolong life. * * *

The boy was 7, a flirtatious kid with an endearing smile and a baseball cap worn more sideways than backwards. He arrived in the clinic with his aunt, a friendly woman who came across more as camp counselor than parent. The boy's mother was an addict who had disappeared several years ago, leaving four children to be farmed out. The boy ended up with this aunt. His father lived elsewhere but visited from time to time. The boy got squirrelish when his aunt asked him to tell me what the problem was. Finally, his eyes on the ground, he said in a barely audible voice, "I wet my bed." "Wet his bed!" his aunt exploded. "He pees in it every night, night in and night out! Do you have any idea what a mess that is? How much work that is?"

The boy kept his eyes down as we talked about the problem, which had lasted on and off for years. The aunt was angry and frustrated but particularly worried because the father has found out about "the problem" and was threatening to come to the house and beat the boy to get him to stop. She believes the dad is serious.

The boy's urine exam was normal, and I sent them home with a lecture about fluid restriction and a plan to get him up once or twice a night to go to the bathroom. I also asked the aunt to keep a diary recording exactly what happened each night. They returned in two weeks with a well-documented tale of continued nightly "accidents" and the intensified fear that the dad was going to hurt the boy if he "wouldn't" stop.

The boy continued to look sheepish. He said he was trying and he didn't want to wet himself but he just couldn't wake up. I believed him. I could only guess at what must have been going on deep in his subconscious, but I was sure that some kind of payback was taking place: urine for neglect, urine for abuse. Urine Power!

There is an antidepressant drug that, taken in small doses, helps children control bedwetting, and I thought it was time to try it. The family was not covered by Medicaid and the aunt looked doubtful about being able to pay the $7 that a month's supply of the medication would cost. I produced the money from my pocket and gave it to them with the prescription and an appointment to return in two weeks with the diary. The boy smiled, the aunt thanked me, and I felt as if I had executed a small, solitary act of health care reform.

Two weeks later they failed to show up for the appointment, and a call to their phone produced a telephone disconnected message. I haven't seen the boy again, and my guess is that somewhere around this city he is still urinating in his bed most nights. He will surely "outgrow" the problem someday, but meanwhile I believe it is his protest, his complaint against a life that is confusing and uncertain, a life where adults come and go, parents vanish, sisters and brothers depart the scene. He is left trying to make do with his smile and his baseball cap while inside he is scared and angry -- and inclined to let the world know about it. Nightly. * * *

While some aspects of medical practice have greatly changed -- the spectacular salvage of ever more minute infants in the neonatal intensive care unit, for example -- others are virtually unaltered from days gone by. At the lower-tech end of pediatrics, the zone in which medical science meets the common problem, practice has changed far less. Issues such as chronic ear infections, eating disorders and, yes, bedwetting are very much as they were when I last visited them. There are medical interventions available for these conditions, but a cooperative family and a fair amount of sweat equity on the part of the physician are essential to achieving good results. For the pediatrician, engagement with patients and families is still a prime ingredient of the treatment of many ills.

The inner city presents a multitude of problems that are unchanged from my earlier experiences. After 20 years during which we as a nation increased spending on our own health by roughly 50 percent (from 9 percent to 14 percent of our GNP) and our number of physicians by 25 percent (from 200 to 250 MDs per 100,000 population), medical practice in the inner city has become more complicated and more strapped for funds. More than a quarter of the District's children live below the poverty line, and in the Cardozo neighborhood that figure is well above 50 percent. While Medicaid helps some, our clinic is a magnet for the uninsured.

Substance abuse, violence and teen pregnancy are far more common and malignant factors of inner-city life than when I first trained in pediatrics. And now, with AIDS and its resurgent fellow traveler TB on the rise, people's health in many neighborhoods in the District is in decline. Medical poverty is the rule. Private insurance is nonexistent; Medicaid is a sometime thing. Although the label "self pay" appears on most of our encounter forms, no one really has money to pay.

Once kids come to Children's Hospital or the hospital's clinics, they have a chance -- largely because the engine of the hospital finance office gets behind them, squeezing every possible Medicaid, health insurance or special fund dollar out of the system. In the community, though, virtually every problem requires creativity by the doctor and a small act of heroism by the patient. With little money, no transportation and, in many cases, minimal English, people face major obstacles in finding a dentist, getting a hearing test, seeing an orthopedist or filling a prescription.

Some days I spend as much time on the phone wheedling, cajoling and explaining as I do practicing medicine. The best diagnosis is worth nothing if I can't invoke some combination of charity and entitlement and persuade the patient to make the necessary trip to places that for many are unfamiliar and often inconvenient. Medical advances and social ones seem to have gone in opposite directions since I had last worked in the inner city. * * *

I labored to finish the paperwork for a strapping 14-year-girl wearing a Georgetown Hoyas sweat shirt and Nike Air sneakers whom I had just seen for a sports physical. She was starting her high school basketball career, and it promised to be a good one. The door of the exam room was open and a pink apparition kept appearing and disappearing from my peripheral vision. There were school forms to be filled out, as well as special sports forms, the clinic's billing sheet, the medical chart, the school excuse and a prescription for a skin cream. The apparition arrived again in the doorway and stood still, a grinning toddler dressed in a bright pink shirt, a Pamper, and white lace-up shoes, with her hair braided in precious, tiny corn rows. The older girl, her mother and I were taken with the beauty and mirth of our visitor.

The little girl toddled into our exam room, her face aglow with her grin and her eyes fixed on the basketball player. She reached the big girl, studied her for a moment and then hoisted her little hand high above her head in the execution of a high five. Laughing, the teenager returned the gesture just as the toddler's perturbed mother rushed in to retrieve the missing tyke. We all had a chuckle. I went back to my work, reflecting on the richness of children, large and small.

I am glad to be practicing medicine again. Health care policy is not going to be made in my exam room, and the frontier of medicine is not going to be moved there either. But children and their parents come in, bringing their most precious possessions -- themselves. They arrive with their ambitions and their apprehensions, their strengths and their illnesses. Together we talk about formula and immunizations, rashes and respiratory infections, acne and sexuality. We traffic in hope and try to construct a better future for the children. This is the work of the pediatrician, and I am happy to be doing it again. CAPTION: Eighteen-month-old patient Joseline Hernandez keeps an eye on pediatrician Fitzhugh Mullan as he works at a desk at the Upper Cardozo Community Health Center in Northwest Washington. CAPTION: Fitzhugh Mullan left the U.S. Public Health Service last year after two decades as a policymaker and returned to seeing patients at the Upper Cardozo Community Health Center. Mullan, author of "Plagues and Politics: The Story of the United States Health Service" and "Vital Signs: A Young Doctor's Struggle With Cancer," has written widely on medicine and health policy. He will contribute regular reports for the Health section on his practice. CAPTION: Mullan examines Andenet Shimeles, a 9-year-old Ethiopian immigrant. The Cardozo clinic's clients are largely uninsured and, in many cases, non-English-speaking. CAPTION: Mullan checks Andenet Shimeles's ear. On the cover, he examines Joseline Hernandez.