But a recent unexplained plunge has advocates wondering if other forces may be at work, including changes in federal law and the way the state handles paperwork.

After four years of growth, Medicaid rolls began leveling off early in 2005, but plummeted this spring. Between April and October, 11,570 Utahns dropped from the government-paid insurance program, representing 7 percent of the caseload.

Health officials suspect Utah's hot job market is driving the trend, but admit they can't say for sure. They know who's leaving - mostly parents and children - but not why.

Medicaid eligibility specialist Jacky Stokes is surveying closed cases to determine if applicants are being wrongfully rejected.

"The survey will tell us did the case worker screw up, or the applicant screw up," said Stokes.

But the study could take six months and won't explain what's happening to patients who exit the program.

"Are they getting insurance or just forgoing health care? We don't know. Nobody seems to know," said Patrice Schell, an advocate at Voices for Utah Children.

It's a critical question, considering Utah's ranks of uninsured swelled seven times faster last year than the national rate, said Judi Hilman, executive director of the Utah Health Policy Project.

"Other states are looking for ways to expand Medicaid to cover the uninsured. But here in Utah, a legislative task force is exploring options for cutting Medicaid," said Hilman. "We're a little out of step."

Declining Medicaid enrollment is a national phenomenon, which advocates believe stems from a 4-month-old federal law requiring Medicaid applicants to provide proof of citizenship.

The law aims to guard against illegal immigrants fraudulently obtaining benefits. But advocates fear it's discouraging people from obtaining health care.

State health department records show missing paperwork contributed to 47 percent of the case closures in July, which saw a record drop in enrollment. Only 5 percent were turned away because they earned too much to qualify for help.

But Stokes doubts the proof-of-citizenship rules are to blame.

She has instructed eligibility workers to extend deadlines for clients who have trouble producing documents. Also, for all Utah-born citizens, workers can access electronic copies of birth certificates using an inter-agency data sharing tool that other states are looking to emulate.

But that doesn't help the 30 to 40 percent of Medicaid enrollees born elsewhere, said Hilman. "We should be data brokering across states."

Medicaid applicant Holly Pray agrees, but says the root of her trouble is a new electronic eligibility system adopted by the Department of Workforce Services.

Now, all documents are scanned into a computer, accessible by hundreds of caseworkers statewide. Clients are no longer assigned to individual workers.

"You get one phone number to call and the person who answers is the person you're dealing with," said Pray, a 24-year-old domestic violence victim and single mother living in West Valley City. "Every time I call, I get a different person with a different answer."

A native of Oklahoma, Pray managed to round up a birth certificate for herself, but says caseworkers lost it.

"I have a 13-month-old daughter, I'm five months pregnant and I've been to the doctor once," said Pray. "I don't want to be on assistance, but I have no choice. I need to care for my babies."

Advocates say Pray's experience should serve as a warning to lawmakers who are weighing transferring all Medicaid eligibility screening to workforce services. Currently, the health department handles cases for disabled and elderly clients.

kstewart@sltrib.com