Shares of Beckman Coulter Inc. sank Friday, a day after the medical-testing instruments maker cut its earnings forecast for the year and reported a 27 percent drop in second-quarter profit.

The Brea, Calif., company said after the market closed Thursday its net income fell to $44.6 million, or 63 cents per share, in the three months that ended June 30. That compares with $60.8 million, or 94 cents per share, in the same quarter last year, when the company had a lower tax rate and fewer shares outstanding.

Revenue grew 19 percent to $902 million, which includes $116 million from the company's Olympus Diagnostics acquisition. But Beckman Coulter also said it saw "continued softness" from revenue in developed markets, excluding Olympus.

Adjusted earnings were 84 cents per share.

Analysts polled by Thomson Reuters expected earnings of $1.07 per share on $929.7 million in revenue.

The company chopped its full-year 2010 earnings outlook to between $3.90 and $4 per share, down from $4.30 to $4.50 per share. It expects total annual revenue of between $3.65 billion and $3.70 billion, below a prior range of $3.75 billion to $3.85 billion.

Analysts expected 2010 earnings of $4.36 per share on $3.76 billion in revenue.

Beckman Coulter said in March it would need to regain approval for its AccuTnI troponin test kits, which are used to determine if a patient has suffered a heart attack.

The company said late Thursday recent compliance and quality challenges in the U.S. market "have prompted significant additional focus and investment in this area to ensure that we live up to the standards our customers expect."

Beckman Coulter also said it has "deferred some other initiatives" pending the resolution of these issues.

Morgan Joseph analyst Bruce Jackson said in a Friday research note some new products likely will be delayed.

"The company does not appear to have a firm handle on the troponin issue," the analyst wrote.

Company shares tumbled $12.76, or 21 percent, to $47.14 in afternoon trading Friday. Earlier the stock hit a 52-week low of $45.23.