American workers think of their health care benefits as inalienable rights, up there with life, liberty, Social Security and a gold watch at retirement. As long as they remain loyal employees, the thinking goes, their companies will take care of them when they get sick.

The best you can say about that cherished ideal is that most employers are at least making an attempt to live up to it, but it gets tougher every year. Employees whose companies are still giving them a free ride on health insurance should count their blessings and prepare for a memo from the boss."The days are over when people can take their health care benefits for granted," said Pat Fres-ton, manager of personnel for Salt Lake-based Questar Corp.'s 2,600 full-time employees. "Companies are working very hard to protect their employees from catastrophic illness, but the days of such benefits being part of automatic compensation are long past - or should be."

Like all companies, Questar - parent company of Mountain Fuel Supply - has watched health care costs, and the insurance to cover them, skyrocket in recent years, far outstripping the consumer price index. Freston and her staff have been as busy as NFL quarterbacks creating a "triple option" for employees that includes self-funded, third party-administered insurance, HMOs (health maintenance organizations), and PPOs (preferred provider organizations).

So far, Questar has managed to keep employee coverage at about the same level but with one difference: the employee pays a larger share of the costs. At Questar, workers pay approximately 20 percent or more (depending on the plan they choose) but with a deductible and a number of other qualifications such as requirements for physician "second opinions," no coverage for certain procedures, such as cosmetic surgery, and incentives for using generic prescription drugs.

And a husband and wife who are covered by two separate company plans can forget about receiving 100 percent (or more) coverage as they may have in the past. Freston says "carved out benefits" has pretty much ended that practice.

First Security Corp.'s 4,000 employees pay 50 percent of the cost of their health insurance premiums and K. Tad Jeppesen, senior vice president and director of human resources, says no one's complaining.

"Our strategy has been that employees pay the same amount as the employer pays," said Jeppe-sen. "We believe that if the employee has that much wrapped up in it, he or she will be careful in utilizing those medical services. It seems to be a trend to have employees pay a larger share of their coverage."

First Security's program is self-funded but administered by Blue Cross-Blue Shield of Utah. Employees may also choose between a HMO and a PPO. Under the conventional coverage, a cap ensures that no employee will have to pay more than $750 for him- or herself, or $2,000 for the whole family, in any one year.

But, again, nothing is etched in stone, Jeppe-sen emphasized. "When costs go up, either you increase employee participation, raise deductibles or cut back on benefits. In any case, we are constantly educating employees that costs are rising." Last year, First Security's health coverage costs rose 18 percent.

Gump & Ayers Real Estate Inc. saw health insurance premiums for its 40 employees jump a flat 50 percent last year, take it or leave it. The company took it, but controller Jean Senarens said employees, formerly funded 100 percent, now have to pay about 10 percent of the costs along with a $100 deductible. Also, routine office calls and physical examinations are not covered and dental care and insuring of dependents is at the employee's expense.

"I think this is as scaled back as we will go," said Senarens. But she concedes there are no longer guarantees in the volatile area of health care benefits. "We'll have to see what happens in October," when the coverage is up for renewal.

Questar, First Security and Gump & Ayers are not alone in their struggle to control escalating costs that threaten their ability to offer employees good health care coverage at a reasonable price.

According to a recent nationwide survey covering more than 10 million workers, employer health care costs jumped nearly 20 percent last year, with the escalating use of mental health and drug/alcohol abuse benefits a major factor.

The survey, by A. Foster Higgins & Co., a New York benefits consulting firm, showed the cost of health care plans rose 18.6 percent, more than double the growth rate for the previous two years. The study involved 1,600 private and public-sector employers with health plans covering 10.5 million employees.

A major factor in health plan cost escalation, according to the survey, is the growing use of mental health and substance abuse benefits. The cost of providing those benefits increased 27 percent in 1988 to an average of $207 per employee, up from the $163 in 1987.

Survey manager John Erb said expenditures for the mental health and substance abuse treatment now account for 9.6 percent of total medical plan costs for employers surveyed, and with mental health benefits rising, employers already are moving to cut costs.

The survey showed that a growing number of employers are now requiring higher levels of copayment for employees who utilize the benefit for inpatient care. And nearly all the health plans have put limits on the amounts they will pay for outpatient treatment.

The study found that 12 percent of the plans now require employees to pay as much as 50 percent of the charges covered by the insurance plan for inpatient mental health treatment. A third of the companies won't count what employees pay out for mental health or substance abuse treatment toward the annual out-of-pocket maximum workers are charged under the health insurance plans.

It also showed that 75 percent of the employers now limit inpatient mental health coverage, with 52 percent allowing 45 days or less a year for inpatient care. Nearly half the employers now place a lifetime payment limit on the amount of inpatient care they will cover.

Nearly all the plans limited the amount paid for outpatient treatment, the survey showed. Two-thirds of the companies place an annual limit, generally $2,000 or less, while 30 percent of the employers limit the amount payable for any one visit to less than $75. Some of the plans use a combination of the limits.

As part of the growing trend toward designating "preferred providers" (the PPOs) for medical treatment, the survey showed that 15 percent of the employers have implemented some form of review to monitor inpatient mental health treatment and 9 percent have procedures to review outpatient treatment.

Erb said employer efforts to curb the cost of substance abuse treatment is reflected by an increase in the number of companies that now conduct pre-employment screening for substance abuse. He said that 24 percent of the employers now screen prospective employees, up from 20 percent last year.

Questar also has a pre-employment drug testing program that Frestor said is an indirect way of reducing health care costs as well as eliminating drug abuse in the work place since health costs are about four times high for drug abusers.

In any case, employees who have seen their payroll deductions for health care premiums rise in recent years, get little sympathy from those who have no coverage at all. In another report released last month, the National Leadership Commission of Health Care said the system needs a major restructuring to make medical services readily available to all Americans while containing costs and improving quality.

In many ways the health care system has done a remarkable job for most Americans, the commission found. Yet, it is ailing from three fundamental problems: accessibility, escalating costs and gaps in quality and research.

Commission leaders said 37 million Americans lack health insurance and nearly as many have inadequate coverage because they can't afford it. That means that one out of every four Americans is uninsured or underinsured.

The answer is a national program of universal access, they suggested.

The nation spent about $550 billion on health care in 1988, the commission report noted. That's 11 percent of the gross national product _ up from about 8 percent in the mid-1970s. If the trend continues, the commission warned, costs will double by 1995 and triple by the turn of the century to claim 15 percent of the gross national product.

And quality control is at best rudimentary, the report said, citing wide regional variations in medical services that are not usually based on medical needs.