Shares of Alexion Pharmaceuticals jumped 20 percent Thursday after the company forecast stronger-than-expected sales of its drug Soliris this year.

Alexion expects $2 billion to $2.02 billion in annual revenue from Soliris, up from $1.55 billion in 2013. Analysts had forecast $1.97 billion in revenue, according to a poll by FactSet.

Soliris was approved in 2007 as a treatment for a life-threatening condition called paroxysmal nocturnal hemoglobinuria, which causes a breakdown of red blood cells and leads to anemia. In 2011 the Food and Drug Administration approved it as a treatment for atypical hemolytic uremic syndrome, which often leads to kidney failure and death. Soliris is an orphan treatment for both of those conditions.

The company lost $19 million, or 10 cents per share, in the fourth quarter because of costs from centralizing some of its business operations, as well as impairment charges. Excluding one-time items, the company earned 87 cents per share, easily topping Wall Street expectations of 83 cents per shares.

Revenue spiked 38 percent to $441.9 million, also beating out analyst projections of $430.5 million.

The Cheshire, Conn., company reported net income of $81 million, or 40 cents per share, and $320.5 million in revenue in the fourth quarter of 2012.

Revenue grew 37 percent in 2013. Based on Thursday's forecast, it is calling for growth of 29 percent to 42 percent in 2014. The company is also projecting adjusted net income of $3.70 to $3.80 per share while analysts were anticipating $3.47 per share.

Alexion is trying to win additional marketing approvals to boost its sales, and earlier this month the company said regulators have deemed its drug Soliris an orphan treatment for the prevention of delayed graft function, a complication for kidney-transplant patients.

Shares of Alexion Pharmaceuticals Inc. climbed $26.86 to $160.59 in midday trading. The stock has been trading at all-time highs in recent months and peaked at $169.98 Thursday.