From the chaotic exodus impelled by Hurricane Katrina has emerged a subset of survivors with compounded problems: people who already were sick before the storm arrived.

Diabetics in need of insulin, heart patients under stress and lacking blood thinners, AIDS and cancer patients cut off from their chemotherapy regimens are among those in tenuous circumstances.

The disaster destroyed or left inaccessible the medical records of untold numbers of people. One oncologist evacuated flooded New Orleans clutching a laptop computer with some patients' records, another threw some paper charts in her truck on the way out, according to The Associated Press. But for most of the 80 children with cancer in Dr. Joseph Mirro's evacuee clinic, their parents' memory of last treatments proved key to resuming therapy.

Even though the New Orleans VA Medical Center flooded, electronic medical records for 50,000 patients of that hospital and surrounding veterans' outpatient clinics survived. On Sept. 1, a Department of Veterans Affairs computer specialist was airlifted from New Orleans carrying backup tapes of all the records, which by the next night had been re-entered into computers in Houston.

Charlie Gephart, records chief for the South-Central VA Healthcare Network, said his office put patient prescriptions and other data tracked at a separate location onto a secure Web site as an interim solution.

But three weeks after Katrina hit, the lack of medical records remains a big obstacle in caring for most evacuees.

"A lot of people walk in and say, 'I take a little blue pill,' " without any idea what it was, Dr. Bethany Gardiner, a pediatrician from Santa Barbara, Calif., who is treating evacuees in Baton Rouge, La., told The AP.

One 65-year-old New Orleans woman whose malignant brain tumor was removed about a month ago was preparing for 30 treatments of radiation at a local hospital when Katrina stuck. Displaced to Houston, she sought help at the University of Texas' M.D. Anderson Cancer Center. She had no medical records and her Louisiana doctor could not be located.

Aware that what the woman described was a particularly fast-growing cancer, Texas doctors approved new brain-imaging studies and immediately scheduled radiation treatments.

Dr. Mark Gilbert, who is treating the woman, said all 11 brain-cancer specialists at the center have treated such Katrina evacuees.

For others with chronic conditions, the prospects are ominous.

About 8,000 people with HIV and AIDS who were displaced now face the massive challenge of trying to manage their disease without their doctors, their clinics and their support systems.

"I'm very frustrated right now," said Noel Twilbeck, executive director of the NO/AIDS Task Force, the oldest HIV/AIDS service organization in the Gulf South. "We absolutely have to get people their medication. This is a frightening situation."

When Michael-Chase Creasy, 49, fled New Orleans, he brought his HIV medicines — but not a lifetime supply. And when he saw television footage from the safety of a Houston hotel room of floodwaters rising above his own 1820s Canal Street home, he knew he would not be returning soon and he was in serious trouble.

The NO/AIDS Task Force has found a temporary home at the Montrose Clinic in Houston, a medical center that specializes in the needs of the lesbian, gay, bisexual and transgender community. Montrose's executive director, Katy Caldwell, told The AP that evacuees have been arriving by the dozens.

Theresa Bieller, 39, of Gulfport, Miss., is wrestling with her medical worries while stuck on a shrimp boat — all her family has left after Katrina destroyed their mobile home.

Bieller was following a 15-pill regimen for a heart problem and other conditions before the storm. Most of her prescriptions were already low or empty. To make matters worse, she had no electricity to operate a nebulizer for her 2-year-old asthmatic daughter, Chloe.

After a few days without medicine, her chest pain and weakness mounting, Bieller checked into a hospital. She came out the next day with a mere three-day supply. She has no insurance and little cash to buy the expensive drugs.

"I called the Red Cross," Bieller said. "They have these medical clinics, but they're for cuts and burns. They say you can go to Walgreen's and get a three-day supply [of drugs] but have to pay for it."

At the Astrodome in Houston, social workers designed a quick screening test for elderly evacuees who may have arrived with ongoing health problems such as diabetes, dementia, high blood pressure or arthritis.

"I was here the first night and we saw a lot of people who had been without their medication for four or five days," said Dr. Carmel Bitondo Dyer, a geriatrician at Houston's Baylor College of Medicine.

One 84-year-old woman relocated to a shelter in Shreveport, La., was discovered to be a lung-cancer patient, said Lisa Clark, an American Cancer Society representative.

The woman, known as "Miss Rita," had already undergone chemotherapy and radiation, but a test shortly before the hurricane showed another spot on one lung. Her family had no clue what to do, but the cancer society was able to track down her records, have them faxed to Shreveport, and schedule a new appointment.

Clark said she assumes other evacuees may need help but have not yet asked.

"A lot of people are thinking, 'I'll be back in New Orleans,' " Clark said.

Dr. Norman Edelman, chief medical officer for the American Lung Association, said he is particularly concerned that mold in water-soaked neighborhoods may have aggravated asthmatic conditions.

"About 30 [percent] to 40 percent [of asthmatics] are allergic to mold," Edelman said. "I anticipate a great need for emergency care. I don't want to sound alarmist, but 4,000 people die of asthma attacks every year in the U.S., and I worry there will be a lot of asthma attacks."