Shares of OraSure Technologies ( OSUR - Get Report) were among the worst-performing health-related stocks Friday, tumbling 17% after the medical diagnostics company posted mixed fourth-quarter results and warned that 2006 earnings would be below Wall Street forecasts.

The company earned $20.6 million, or 44 cents a share, on sales of $18 million. Excluding an $18.2 million tax benefit, the company earned 5 cents a share during the fourth quarter. Analysts polled by Thomson First Call expected earnings of 5 cents a share and sales of $18.1 million. During the year-earlier quarter, the company recorded a loss of $245,000, or 1 cent a share, on sales of $14.2 million.

OraSure sees 2006 earnings of 13 cents to 15 cents a share, including 4 cents to 5 cents in stock-based compensation costs. The company, whose biggest product is a rapid HIV test, predicts sales growth of 25%, which would imply sales of just under $87 million. Analysts project earnings of 21 cents a share and sales of $87 million. Shares were trading down $1.91 to $9.10.

Diagnostic Products fell 5% after the maker of diagnostic test kits posted fourth-quarter results that fell below expectations. The company earned $13.1 million, or 43 cents a share, up from $11.1 million, or 37 cents a share, a year earlier. Analysts expected earnings of 66 cents a share. Sales rose to $123.8 million from $118.7 million a year earlier, but missed analysts' target of $19.6 million. Shares were trading down $2.32 to $47.40.

Shares of Coventry Health Care fell 6% after the company posted better-than-expected fourth-quarter earnings but warned that first-quarter earnings would be lower than analysts' estimates. For the fourth quarter, the company earned $126.4 million, or 77 cents a share. Excluding one-time items related to Hurricane Katrina, the company posted earnings of $133.1 million, or 81 cents a share, a penny above analysts' forecast. Coventry reported sales of $1.72 billion, compared with Wall Street's projection of $1.70 billion. During the year-earlier period, the company earned $91.8 million, or 67 cents a share, on sales of $1.38 billion.

For the first quarter, Coventry Health Care sees earnings of 71 cents to 73 cents a share, including costs of about 8 cents a share related to stock-based compensation and Medicare Part D losses. The company predicts sales of $1.84 billion to $1.9 billion. Analysts project earnings, including stock-based compensation costs, of 84 cents a share and sales of $1.88 billion. Shares were trading down $3.54 to $55.78.

Wright Medical ( WMGI - Get Report) fell 8% after the orthopedic device maker warned that first-quarter earnings would be below expectations. For the fourth quarter, the company posted earnings of $2 million, or 6 cents a share, on sales of $80.3 million. Excluding items, the company earned $5.9 million, or 17 cents a share. Analysts expected earnings of 15 cents a share, before items, on sales of $78.8 million. During the year-earlier quarter, the company earned $6.3 million, or 18 cents a share, on sales of $77.7 million. Excluding items, the company earned $8.2 million, or 23 cents a share, a year earlier.

Looking ahead, Wright Medical projects first-quarter earnings of 10 cents to 12 cents a share on sales of $81 million to $83 million. Wall Street forecasts call for earnings of 21 cents a share and sales of $86.7 million. Wright shares were down $1.68 to $20.05.

Shares of Ventana Medical Systems ( VMSI) slid 10% after the maker of reagents and other instruments posted mixed fourth-quarter results and issued a lower-than-expected 2006 guidance. The company earned $10.6 million, or 29 cents a share, on sales of $54.3 million, for the fourth quarter. The earnings beat analysts' projection of 26 cents a share, but sales fell short of analysts' target of $55.6 million. During the year-earlier quarter, Ventana earned $8.6 million, or 24 cents a share, on sales of $48 million.

For 2006, Ventana expects earnings of 95 cents a share and sales of $236 million to $238 million. Analysts project earnings of $1 a share on sales of $242.6 million. "The anticipated earnings number is below the current range of published estimates, but consistent with management's decision to accelerate investment in R&D and commercial operations to jump start certain product development and technology programs while strengthening the global sales and support organizations," the company said. For 2007, the company sees sales growth of at least 25% and operating income between 23% and 25% of sales. Shares were down $4.05 to $36.33.

Acorda Therapeutics ( ACOR - Get Report) shares gained nearly 12% on their first day of trading. The biopharmaceutical company's initial public offering priced at $6 a share, well below its targeted range of $11 to $13. The shares recently changed hands at $6.70.

Other health care volume movers included Pfizer ( PFE - Get Report), down 34 cents to $26; Genta , down 31 cents to $2.83; Pain Therapeutics ( PTIE), up $1.10 to $10.20; Johnson & Johnson ( JNJ), down 10 cents to $58.45; Schering-Plough , down 3 cents to $18.47; Boston Scientific ( BSX - Get Report), down 21 cents to $21.76; Amgen ( AMGN), up 19 cents to $71.20; Teva Pharmaceutical Industries ( TEVA), up 88 cents to $40.88; Bristol-Myers Squibb ( BMY), down 28 cents to $22.31; Elan ( ELN), down 36 cents to $14.09; and Merck ( MRK), down 15 cents to $34.19.