There are 75,000 genetic tests available for sale today – a flood of information that could provide major new insights into health or an unwieldy abundance of information that overloads doctors and drives medical spending higher.

A new study in the journal Health Affairs reveals an explosion of genetic tests over the past four years, with about 10 new ones entering the market each day. Another study, of hundreds of primary-care providers in New York City, found only one-third had ever ordered a genetic test or referred a patient for counseling. A minority –14 percent – said they felt confident interpreting results.

The studies point to the huge opportunity and challenges that face the booming business of clinical genomics, which is forecast to grow to a $7.7 billion global industry by 2020.

As the cost of sequencing genes has plummeted and tests have proliferated, the knowledge about the best practical uses of such information in the real world has remained relatively nascent. Doctors want better tools to support their decisions.

“If I were a provider trying to figure out what to order, that’s where this is in some way the Wild West, because we have so many tests out there,” said Kathryn Phillips, a professor of health economics and health services research at the University of California at San Francisco. “Trying to sort out what to use, when and how much to pay for a test is pretty complicated.”

Phillips led the work to tally up the number and type of genetic tests in circulation. Her team limited their search to clinical tests ordered by doctors – leaving out genetic tests marketed directly to consumers.

Of the 75,000 tests identified as of August, many were redundant – there were only about 10,000 unique test types, because tests offered by different laboratories may test the same genes or a panel of genes. That adds to the difficulties for doctors, who have to figure out which tests are appropriate and worth the price and also make sure they can translate the results into meaningful information for patients.

Genetic tests for pediatric and rare diseases are growing fastest, followed by prenatal, cancer, hematology and neurology tests.

To Diane Hauser, a senior associate at the Institute for Family Health at the Icahn School of Medicine at Mount Sinai, the growth in genetic tests shows the complexity of the landscape facing health care providers.

“Ten new tests a day – no one can be expected to master that,” said Hauser, who separately found that most primary care providers have little confidence in their ability to interpret test results and low trust in companies that offer genetic testing.

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