UnitedHealth Group Inc posted a higher-than-expected second-quarter profit on Tuesday, helped by stronger enrollment, and the insurer raised its full-year earnings forecast.

The largest U.S. health insurer by market value also cited moderated use of healthcare services by its members for helping lower its medical claim costs. The industry has benefited from Americans avoiding procedures and doctor visits during the weak economy.

UnitedHealth's net income rose 13 percent to $1.27 billion, or $1.16 per share, from $1.12 billion, or 99 cents per share, a year earlier.

Analysts on average expected 94 cents per share, according to Thomson Reuters I/B/E/S.

According to UnitedHealth, the analysts' estimate factored in costs of as much as 15 cents per share from the potential insolvency of an unaffiliated insurance carrier in Pennsylvania. UnitedHealth is likely to still need to accrue such costs, but did not have to in the second quarter.

Revenue rose 8 percent to $25.23 billion.

Membership stood at 34.18 million at the end of the quarter, up 5 percent from a year ago. Membership in plans serving employers and individuals, older people using Medicare benefits and low-income Americans on Medicaid all rose.

The company forecast full-year earnings of $4.15 to $4.25 per share, up from its previous range of $3.95 to $4.05. Analysts are looking for $4.19.

UnitedHealth shares have risen some 44 percent this year, ahead of the 40 percent climb for the S&P Managed Health Care index of large insurers <.GSPHMO>.

(Reporting by Lewis Krauskopf; Editing by Lisa Von Ahn)