* Chinese patients take on debt to fund rising medical costs

* Personal medical expenditure expected to hit $1.9 trln by 2025

* Public health insurance broad but shallow, so much not covered

* Patients liable for about half of total healthcare spending

* Consumer borrowing has tripled since 2010

By Adam Jourdan and Ben Hirschler

SHANGHAI/LONDON, July 10 (Reuters) - As China's medical bills rise steeply, outpacing government insurance provision, patients and their families are increasingly turning to loans to pay for healthcare, adding to the country's growing burden of consumer debt.

While public health insurance reaches nearly all of China's 1.4 billion people, its coverage is basic, leaving patients liable for about half of total healthcare spending, with the proportion rising further for serious or chronic diseases such as cancer and diabetes.

That is likely to get significantly worse as the personal healthcare bill soars almost fourfold to 12.7 trillion yuan ($1.9 trillion) by 2025, according to Boston Consulting Group estimates.

For many, like Li Xinjin, a construction materials trader whose son was diagnosed with leukaemia in 2009, that means taking on crippling debt.

Li, from Cangzhou in Hebei province, scoured local papers and websites for small lenders to finance his son's costly treatment at a specialist hospital in Beijing, running up debts of more than 1.7 million yuan, about 10 times his typical annual income.

"At that time, borrowing money and having to make repayments, I was very stressed. Every day I worried about this," said Li, 47, adding that he and his wife had at times slept rough on the streets near the hospital.

"But I couldn't let my son down. I had to try to save him," he said.

Li's boy died last year.

The debts will weigh him down for a few more years yet.

Medical loans are just part of China's debt mountain - consumer borrowing has tripled since 2010 to nearly 21 trillion yuan, and in eight years household debt relative to the economy has doubled to nearly 40 percent - but they are growing.

That is luring big companies like Ping An Insurance Group , as well as small loan firms and P2P platforms, as China's traditional savings culture proves inadequate to the challenge of such heavy costs.

The stress is particularly apparent in lower-tier cities and rural areas where insurance has failed to keep pace with rising costs, said Andrew Chen, Shanghai-based healthcare head for consultancy Parthenon-EY.

"It's a storm waiting to happen where patients from rural areas will have huge financial burdens they didn't have to face before," he said, adding people would often take second mortgages on their homes or turn to community finance schemes.