High blood pressure is the sneaky one, the so-called silent killer.

You can have it for years and never feel it.

Even if you know your pressure is up, and your doctor gives you medicine, it's only too likely that you'll either forget to take it regularly -- no symptom to remind you -- or dismiss it altogether because you don't feel like you need it.

You probably won't die of hypertension, but if you've got it, you very likely will die -- or have a permanent disability -- from something it causes.

Dr. John H. Laragh, director of the Cardiovascular Center of New York Hospital/Cornell University Medical College, calls high blood pressure "undoubtedly the largest single public health probelem in the world in terms of numbers because it is generally recognized to be the main predisposing factor in the occurrence of heart attack, stroke, kidney failure and heart failure.

"these four conditions," he notes, "are, in the aggregate, far and away the largest single factor in all sickness and death. Maybe three to five times as much as cancer."

Because of the statistics, and because many of the medications developed to control high blood pressure have side effects, ranging from the unpleasant to the unacceptable, research in the field is constant and often controversial. tThere are new, sometimes conflicting studies, new drugs and intriguing experiments using biofeed-back and self-hypnosis.

Dr. Laragh has concentrated on the physiology and biochemistry of the problem, as well as its medical treatment. In 1969 he won a share in the prestigious Stouffer Prize for his work confirming the role played in the physiology of blood pressure by the kidney hormone renin. And he and colleagues, including his biochemist wife, have devised a computer-assisted laboratory test which, he believes, ought to eliminate the traditional hit or miss system of treating hypertension.

But although Laragh's medical peers are quick to acknowledge his contributions, they are less enthusiastic about the test, or about some of his other current propositions.

"He is a crusader," cautiously commented a Washington area hypertension specialist, "but I'm not convinced (about the test). You can do empirically what he does with renin-sodium profiling."

Laragh's basic thesis, one with which his colleagues agree, is that "high blood pressure is something like a fever. When a patient has a fever, we now understand that it could have many different causes and we use entirely different things to control it. It's the same thing with high blood pressure."

Where laragh begins to diverge from the traditional approach is in the use of the test to pinpoint the correct treatment. The hormone renin is part of the body's intricate system regulating blood pressure -- now increasing it, now lowering it, as the body's functions require. Renin acts as a vascular constrictor, raising the pressure of the blood through the system, even as tightening the nozzle of a hose increases the pressure of the water.

Laragh's work has convinced him that in the majority of high blood pressure cases, the culprit is too much of this hormone. He is optimistic that a new drug, captopril (an analog of snake venom, which supresses renin), will have a major impact on treatment. Because of some evidence of toxic effects, however, the drug has not yet been approved for general use.

In about a third of high blood pressure cases, the renin in the system is low, and the problem is caused by too much sodium in the system, says Laragh. Studies show, he says, that the low-renin hypertensives have a lower risk of serious complications than high-renin patients. These low-renin, high-sodium cases are sucessfully treated with the use of diuretics and restricted salts diets, as physicians have been doing for some years.

Laragh believes the renin-sodium profile test to be particularly useful because it shows whether hypertension patients have high, medium or low renin types of the ailment, therefore pinpointing the most efficacious treatment. It screens for the two major types of hypertension which are surgically curable -- a narrowed kidney artery or a benign adrenal gland tumor. And, he believes, it helps predict which patients have the greatest risk of hypertension-induced heart attacks or strokes.

The trouble is, many doctors have found, there are too many hypertensive patients whose response to drugs does not correlate with test results, or whose need for surgery is not hinted by the test.

The trouble is Laragh believes, that either the test was not conducted properly or its lack of acceptance simply reflects the natural reluctance of of the medical establishment to change its ways. (Traditional treatment of high blood pressure generally starts with prescription for a diuretic and a restricted salt intake, moving on later to stronger medications, if needed.)

Laragh's work also has convinced him that restriction of salt should not be imposed automatically because, he has found, "A low salt diet or a diuretic can actually raise the pressure of those with high renin in the blood."

(Salt foes, recently reported McGraw Hill's Medical World News, are, however, "unshaken.")

Dr. Edward Fries, another nationally known expert in hypertension who heads the Georgetown University Medical School's cardiovascular research lab and its hypertension clinic, and is senior medical investigator at the Veterans Administration Hospital in Washington, does not use the Laragh test. (He is conducting tests on captopril at the VA facility.)

"I haven't found the test that reliable or that useful," he said.

Fries, who has co-authored a lucid book for lay readers called "The High Blood Pressure Book," (Painter-Hopkins, $12.95) is also a strong advocate of removing as much salt as possible from everybody's diet.

But whatever the controversy over treatment, the most important thing is to find out if your pressure is up. Especially if it runs in your family, if you are over 35, male, or black.(Blacks not only are more susceptible, but have a significantly greater risk of death than whites.) Also if you are overweight, smoke, are a woman over 50, or on birth-control pills.

Almost any nurse and many technicians are adept at the simple blood-pressure reading test. It takes less than a minute. It's worth a lifetime.