"You've got to spend money, to make money," the old saw goes. This week we have a case study on how far the government can go in spending money in attempting to save on the Medicaid program, an effort that led the Health Care Financing Agency to fund an upcoming telephone poll to find out, among other things, how effective the ABC television magazine program "20/20" is with its viewers.

HCFA administers the federal Medicaid program which, at a projected $18 billion for fiscal 1982, is high on the Reagan-Stockman list for budget cutting. Medicaid pays for health care of the needy, and surgery is within the program's range of services.

For several years officials in the government and in private health care programs, such as Blue Cross-Blue Shield, have been concerned that doctors were suggesting surgery where it might not be needed. Part of the big growth in Medicaid costs has come from the growing number of operations being performed.

These government and nongovernment officials got behind a program to encourage patients to get a second opinion, from another doctor, when advised that they needed surgery. The hope was, and it proved correct, that often the second opinion would be that some other medical approach could be used rather than a costly operation.

How do you get patients to seek out a second opinion? Publicize the idea was one answer, and the private health care programs developed sophisticated ad campaigns. You see them on television.

HCFA decided it, too, should take some steps. One of them was to establish, in 1978, the "National Second Surgical Opinion Program (NSSOP) Hotline," a toll-free telephone number, that citizens could call from anywhere in the country. The person who answered the phone would not give medical advice. Instead the caller would be referred to what one HCFA official recently called "volunteers" in each state. These, the official said, "could be carriers involved in health care programs such as Blue Cross-Blue Shield or insurance companies." The "volunteers" would listen to the medical complaint and suggest two or three physicians nearby to whom the caller could turn for a second opinion.

One can understand the usefulness of the hotline, and perhaps why HCFA is financing it. But once the government gets into one of these things, it follows its familiar pattern of expansion. A contractor was hired to handle the telephone setup. The current one, an HCFA official said recently, charges about $40,000 a year and in 1980 handled "about 1,000 calls a month."

Is that enough to justify continuing this program in the tight-budget Reagan years?

Enter "20/20," the ABC television program. It has put together a segment on "un-necessary surgery," according to HCFA documents, and in it the NSSOP Hotline number will be shown "to an estimated TV audience of at least 15 million" along with the HCFA public service message about it.

That should be enough. But for government programs like the hotline, that need something to show Congress to justify additional funding, "20/20" offers "a unique opportunity for HCFA to record mass media reaction to one of its beneficiary awareness programs." That quote was from a request for Office of Management and Budget approval of a special $1,500 telephone poll that would collect the reactions from the first 500 callers to the hotline after the "20/20" program appeared. The cost is low because HCFA's own Office of Research, Demonstrations and Statistics (which itself has a $50-million-a-year budget) will do the analysis.

Among the poll's 10 questions are: "Did you watch the recent '20/20' program about surgery?", "Did you know about our service before the '20/20' program?", "Are you a regular viewer of '20/20,' were you thinking about getting a second opinion?"

This may be an austere administration, but approval was granted for the poll -- supposedly because the "20/20" segment was scheduled for Feb. 19 -- waiving the required 10-day comment period after publication in the Federal Register. It was approved Feb. 10, and published in the Feb. 17 Federal Register (page 12578).

HCFA now hopes the segment will be aired this Thursday, and the poll results will be available within six to eight weeks. What will it prove, except the pulling power of "20/20"?

By the way, the NSSOP Hotline number is 800-638-6833. Let's take another poll and see how many people with surgical problems read this column?