The nation's largest health insurer reported a 30 percent surge in second-quarter income, boosted full-year earnings guidance and broke the $50 billion mark in quarterly revenue for the first time in company history.

The insurance business at UnitedHealth Group continued to benefit during the quarter from a scaled-back presence on health exchanges that were launched under the federal health law, a source of red ink last year. But the Minnetonka-based company saw even more growth from its Optum division for health care services.

On a day when much of the health care world was focused on the failure of Republicans in the U.S. Senate to deliver on promises to repeal and replace the ACA, UnitedHealth Group Chief Executive Stephen Hemsley did not directly comment on the developments, referring instead to the potential impact from health policy changes.

"The headwinds are largely around externalities — national and state health care policies, funding trends and taxes — which we and you are all following closely," Hemsley said during a conference call with investors.

"We respect the complexity of the social, economic and political matters that are intertwined here," Hemsley said. "Certainly, at this stage in the national conversation, speculation about any outcome here would be just that."

The political news out of Washington seemed to weigh on the share prices for three of the nation's largest health insurers, with stock prices for Aetna, Anthem and Humana off by about 1 percent each. UnitedHealth Group shares ended the day up slightly.

Through its UnitedHealthcare subsidiary, UnitedHealth Group significantly pulled back this year from government-run "exchange" marketplaces that were created by the ACA, also known as Obamacare. The exchanges are an option for people in the individual market, which serves self-employed people and those who don't get employer coverage.

The company is still a large operator of Medicaid health plans. Eligibility in the Medicaid program expanded under the ACA and would have faced likely cuts under the Republican plan.

If the potential for health policy changes could provide a headwind, Hemsley also rattled off a list of factors that could continue to drive growth, saying "the fundamentals of our businesses remain strong."

Analysts said the quarterly results were strong, with Leerink analyst Ana Gupte writing in a note to investors: "With the exception of [the individual market], where revenue contracted with the expected exit from Obamacare exchanges, the company continued along its solid path of revenue and membership growth."

UnitedHealth Group's Optum division, which is based in Eden Prairie, includes a large business managing pharmacy benefits for other health plans. It also sells data services to health care providers and provides outpatient care directly to patients.

Earlier this year, Optum announced a $2.3 billion deal to purchase a larger surgery center group, making the company one of the nation's largest providers. Optum Chief Executive Larry Renfro said Tuesday the surgery center business is performing slightly ahead of expectations and is establishing six surgical outpatient facilities this year.

Optum's MedExpress chain of urgent care clinics, meanwhile, added 20 locations during the first half of 2017. When asked during a call with investors if the company was feeling competitive pressures from others offering health care services, Renfro said Optum benefited from being relatively early to the business, which was launched in 2012.

"We didn't miss any boat here," Renfro said.

On Monday, UnitedHealthcare and AARP announced the renewal of a 20-year-old marketing partnership for selling Medicare Part D prescription drug plans. The insurer has seen notable growth this year in its business selling "Medicare Advantage" health plans, where seniors receive their government health insurance benefits through a private managed care company.

"We estimate that government yields, led by Medicare Advantage, were stronger than projected," wrote Christine Arnold, an analyst with Cowen, in a note to investors.

In the second quarter, UnitedHealth Group posted earnings of $2.28 billion on $50.05 billion in revenue. The profit was up about 30 percent compared with earnings of $1.75 billion during the year-ago quarter.

After adjusting for one-time factors, earnings per share of $2.46 beat analyst estimates by 8 cents.

UnitedHealth Group now expects adjusted net earnings of $9.75 to $9.90 per share for the year, up from the previous range of $9.65 to $9.85 per share. The increase and narrowing of the guidance is "prudently recognizing the strength in this quarter," said John Rex, the company's chief financial officer.

Christopher Snowbeck • 612-673-4744

Twitter: @chrissnowbeck