Global insurance broker and risk management firm Arthur J. Gallagher & Co. boosted its profit 85 percent in the first quarter, from  $15.2 million in 2011 to $28.1 million this year, due to strong growth in commission and fee income.

First quarter combined insurance and risk management revenue grew 22 percent to nearly $547 million for the Illinois-based firm.

For the insurance brokerage segment by itself, total revenues were up 22 percent to $385 million. Organic (excluding acquisitions) commission and fee income ($291.1 million) was up 3.2 percent while supplemental commission ($17.1 million) revenue grew 9.1 percent in the quarter. Organic contingent commission income ($16.6 million), however, was down slightly by 1.2 percent from last year’s first quarter.

The insurance unit completed 12 acquisitions with annualized revenues of $30.6 million in the quarter.

The risk management segment reported total revenues were up 8 percent to $141 million and organic fees were up 7.0 percent to $139.8 million.

For the combined operations, the company said there was 23 percent growth in adjusted EBITDAC and 12 percent growth in adjusted diluted net earnings per share.

“Our positive operating momentum continued in the first quarter of 2012 despite it being seasonally our smallest quarter. Coming off a strong finish in 2011, we are pleased to see another quarter of strong organic growth, improved adjusted EBITDAC margins and improved adjusted diluted net earnings per share,” said J. Patrick Gallagher, Jr., chairman, president and CEO.

Gallagher said his firm is “seeing further evidence of market firming and our customers’ businesses are showing growth.”