Sure, Internet and tech firms are supercharging business growth in Los Angeles, but there’s another industry that’s made a surprisingly strong showing on the fastest growing list this year.

Health care companies captured two of the top 10 slots and seven spots on the entire list, topping even real estate-related companies, long a leading regional industry.

“The health care industry is growing at such a fast rate of 7 to 8 percent a year and is already a $4 trillion economy worth 20 percent of our nation’s gross domestic product. So it’s only natural to see a fair number of health care-related companies on this list,” said Glenn Melnick, professor of health economics at the University of Southern California.

This huge growth is being fueled by several converging trends: an aging population requiring more health care, continual improvements in technology, chronic staffing shortages and a hugely complex bureaucracy.

This last point provided the driving force behind the No. 2 company on the list: Coding Source LLC, which provides medical coding services for billing purposes. Each medical procedure carries its own special codes, with major procedures like heart surgery carrying up to a dozen. At each hospital or private medical group, somebody has to convert the procedure written down by the doctor into the various codes so that the patient’s insurance company can be billed.

“It’s incredibly complex and it requires very specialized training that very few people have,” said Coding Source President Greg Sinaiko.

Medical coders are not the only people in short supply indeed, all across the medical spectrum staffing shortages abound, from nurses to general care physicians to physical therapists. This has provided the entr & #233;e for the No. 6 company on the list: Emerald Health Services, a Marina del Rey-based staffing business. “There is such great need out there for qualified staff that even though there are plenty of staffing companies out there, there’s plenty of room for one more,” said Emerald Chief Executive Mark Stagen.

Another big driver for the local health care industry is the aging of the population. Two companies that made the fastest growing list cater to the senior health-care market: No. 87, TwinMed LLC, and No. 90, Livehome Inc. TwinMed is a medical supply distributor to nursing homes; Livehome provides at-home care for seniors.

The other health care-related companies are: No. 72 Pathnet Esoteric Laboratory Institute, a women’s health clinical lab; No. 82 Tristar Risk Management, which administrates worker compensation claims; and No. 83 Discus Dental Inc., which manufactures dental products.

Melnick said the health care representation on the fastest growing list is likely only to grow as the population ages and technology continues to change the industry. “You’ve got a health care information technology explosion that’s only now beginning to take shape as the industry catches up with other sectors.”

He added that whatever health care reform does emerge in the next few years, it won’t stop the health care juggernaut. “The only real uncertainty is where the money will come from. Not how much money overall, but who will be footing the bill.”