Cost of blood jumps as supplies begin running low.

In John Le Carre's latest novel, "Single & Single," renegade banker Tiger Single ominously advises his cohorts that "human blood is a commodity."

In Los Angeles, it's a commodity that's becoming harder to find - and more expensive.

Demand for blood is rising at hospitals throughout L.A. County while donations to blood banks continue to fall. In addition, the American Red Cross will use a new screening procedure starting next month that will boost the price hospitals must pay per unit by almost 10 percent - a cost that will probably be passed along to the patient.

Demand for blood in Los Angeles has steadily risen over the past nine months, according to American Red Cross spokesman Marc Jackson. Donated blood is used in everything from organ transplant surgeries to treating trauma patients to comprehensive cancer treatments.

At the same time, the city's blood supply is diminishing rapidly. Jackson said there's a drop in donations every summer when schools go out of session and the main source of blood donations - high school and college blood drives - disappear. But this year, he said, the drop is frightening.

"It's really severe," he said.

At this time last month, the American Red Cross Blood Services in Southern California, which distributes blood to about 150 hospitals in L.A., Orange and San Diego counties, had a surplus of several blood types. Now the organization is well below desired reserves for every single blood type.

At present, for example, the Red Cross has only 6 percent of reserves for O negative, the most important blood type because it can be given to anyone. This compares with 22 percent of reserves in May.

"Southern Californians donate less blood than any other major metropolitan area in the United States," Jackson said. "Forty percent of the blood we use is imported from other areas."

With changing attitudes toward blood donation - part of the overall climate of fear surrounding blood during the era of HIV - it takes a lot more education and reassurance to get people to donate.

"I don't think donations have fallen because people are mean or they don't care," said Dr. Janice Nelson, medical director of the blood bank at L.A. County-USC Medical Center. "To use a not-so-nice word, some people are chicken. And then there are other factors, related to convenience. It's hard just to go to a donor center and sit there for an hour and be tied up to a machine and not be able to do anything else."

While blood banks have often been criticized for crying wolf - citing dramatic scarcities in reserves when asking for blood donations - researchers insist that this time around, the threat is real.

The National Blood Data Resource Center in Bethesda, Md., an independent research organization, predicts that in the coming months, there will be a shortage of almost 250,000 units of blood nationwide. Potentially. this could lead to a postponement of non-life-threatening surgeries and require the import of blood from other areas for trauma patients.

Complicating the current shortage was a controversial recommendation made by an advisory panel to the Food and Drag Administration earlier this month that would limit the pool of potential donors.

The panel said that people who lived in England for an extended time between 1980 and 1996 should be barred from donating blood because of the risk of Creutzfeldt-Jakob disease, more commonly known as Mad Cow disease. Scientists still are unsure about how Mad Cow disease, which attacks the brain, is transmitted among humans.

It is estimated that such limitations would cut the U.S. blood supply by 2.2 percent, eliminating hundreds of thousands of units.

"The (FDA panel) is a political animal and they really do frequently succumb to decision-making that isn't scientifically sound," Nelson said. "The fact is, the more donors we eliminate based on theoretical science or political pressure means that there is less blood we're going to be able to collect."

While a test for Mad Cow disease is currently beyond the reach of science, the FDA recently gave approval to a new screening procedure that will target hepatitis C and HIV.

The American Red Cross, which distributes more than half the blood collected annually in the United States, has opted to start using the procedure in July.

The new test, known as nucleic acid testing, is considered a key improvement in discovering viruses like HIV and hepatitis C before they enter the blood supply. In the traditional procedure used to screen blood, tests look for antibodies of viruses, which indicate the system is already fighting an ailment.

With nucleic acid testing, viruses are detected directly, even before antibodies can be created. According to the American Red Cross, the new test could prevent more than 200 units of tainted blood each year from being used.

But this new test comes at a greater expense. Nucleic acid testing will add $6 to each unit (or pint) of blood. The cost per unit is now between $80 and $100. There are 10 units of blood in a human body.

In Los Angeles, the new test could mean an additional expense of up to $2.8 million for the hospitals that use blood from the Red Cross. It's inevitable that the increase in price will be passed along to patients, Nelson said.