Gen-Probe Inc. said Thursday its profit increased in the third quarter as the diagnostic test maker's revenue grew 8 percent amid higher revenue from blood screening products.

But the company pared back its forecast for full-year results, sending its shares down $4.06, or 8.3 percent, to $45 in aftermarket trading. The stock added $1.14 to $49.06 during the regular session.

Gen-Probe reported net income of $27.4 million, or 56 cents a share, in the three months ended Sept. 30. That compares with net income of $22.2 million, or 44 cents a share, in the same period last year.

Excluding one-time items, the company said it earned 57 cents a share.

Total revenue rose to $132.6 million from $122.7 million the year before.

Analysts polled by Thomson Reuters expected net income of 50 cents a share on $135.3 million in revenue.

"Third quarter product sales were about one percent shy of our expectations from last quarter, as the cumulative effect of macroeconomic headwinds finally weighed on overall testing volumes," said Carl Hull, Gen-Probe's chief executive. "At the same time, we continue to out-grow our domestic and international markets, and our competitive positions, market shares and pricing are solid."

Clinical diagnostics revenue rose 8 percent to $74.9 million, while blood screening revenue rose 11 percent to $50.3 million. Research product and services revenue fell 21 percent to $3.1 million, mainly due to the divestiture of the company's BioKits food testing business late last year and foreign exchange rate fluctuations.

Looking ahead, the company said it expects adjusted net income per share in 2010 to range from $2.12 to $2.15. It had previously projected the high-end of the range to be $2.25 a share.

Gen-Probe also lowered its full-year revenue forecast to between $541 million and $546 million, down from a range of $545 million to $562 million.

Analysts expected 2010 net income of $2.16 a share on revenue of nearly $556 million.