Updated from 3:33 p.m. EDT

Shares of Gentiva Health Services ( GTIV) were among the worst-performing health-related stocks Thursday, falling 16.4% after the company posted first-quarter earnings and sales that disappointed Wall Street.

The provider of home health services posted earnings of $4.1 million, or 17 cents a share, on sales of $207.1 million. Analysts surveyed by Thomson First Call were expecting earnings of 21 cents a share on sales of $217.8 million. A year ago the company reported adjusted earnings of $4.3 million, or 16 cents a share, on sales of $205.9 million, which excludes special items.

Looking ahead, Gentiva now expects 2005 earnings of 75 cents to 83 cents a share, up from previous guidance of 72 cents to 80 cents a share. Part of the company's upward revision is due to a delay in the implementation of accounting rules on stock-based compensation, which will now go into affect during fiscal 2006, instead of the second half of 2005. The accounting change would have increased expenses by 6 cents to 8 cents a share.

The company also said that its outlook is based on the acquisition of Heritage Home Care Services, a conservative view regarding sales from its Cigna relationship -- based on first-quarter results -- and the company's decision to invest in clinical capacity and branch operations. Gentiva backed its 2005 sales estimate of $870 million to $890 million. Analysts are expecting earnings of 83 cents a share on sales of $893 million. Shares traded down $3.42 to $17.41.

Bentley Pharmaceuticals ( BNT) rose 22.6% after the company posted first-quarter results that easily topped expectations. The drug delivery company earned $2.2 million, or 10 cents a share, on sales of $24.2 million. Analysts were expecting earnings of 5 cents a share on sales of $20.1 million. Results were helped by sales volume growth in Spain, a strengthening of the euro against the dollar and continued growth in pharmaceutical sales to licensees, both in Spain and outside of Spain. A year ago the company earned $800,000, or 4 cents a share, on sales of $17.3 million. Shares traded up $1.71 to $9.29.

Shares of Symmetry Medical ( SMA) rose 7.1% after the provider of orthopedic products posted first-quarter results that were ahead of expectations and said that investors could expect more of the same during the second quarter. The company earned $7.7 million, or 22 cents a share, on sales of $63.8 million. Analysts were expecting earnings of 18 cents a share on sales of $55.4 million. A year ago the company reported a loss of $106,000, or 1 cent a share, on sales of $45.8 million. Looking ahead, Symmetry forecast second-quarter earnings of 23 cents to 24 cents a share on sales of $63 million to $66 million. Analysts had been expecting earnings of 22 cents a share on sales of $60.5 million. Shares traded up $1.34 to $20.20.

Third Wave Technologies ( TWTI) fell 12.5% after the developer of molecular diagnostic products posted first-quarter results that were weaker than expected and warned that its research revenue for 2005 would be at the lower end of its previous guidance. The company reported a first-quarter loss of $4.4 million, or 11 cents a share, on sales of $7.1 million. Analysts were expecting a narrower loss of 3 cents a share on sales of $9 million. A year ago the company earned $2.8 million, or 7 cents a share, on sales of $15.3 million. Looking ahead, Third Wave reiterated its 2005 forecast for clinical molecular diagnostic sales of $23 million to $26 million, but said that research revenue would be at the low end of its previously issued guidance of $10 million to $15 million. Shares traded down 60 cents to $4.20.

Shares of SciClone Pharmaceuticals ( SCLN) rose 4.2% after the company posted a narrower first-quarter loss on sales that were better than expected. The biopharmaceutical company posted a loss of $1.5 million, or 3 cents a share, on total sales of $6.8 million. Sales from the company's lead product, Zadaxin, rose 23% to $6.7 million. Analysts were expecting a wider loss of 8 cents a share on sales of $6.1 million. A year ago the company reported a loss of $3.1 million, or 7 cents a share, on sales of $5.6 million. Looking ahead, SciClone left its 2005 guidance unchanged, saying it continues to expect a loss of 31 cents to 36 cents a share on Zadaxin sales of $25 million to $26 million. Shares traded up 9 cents to $2.23.

Other health care volume movers included Pfizer ( PFE), up 2 cents to $27.85; Elan ( ELN), up 30 cents to $6.24; Gen-Probe ( GPRO), down $8.44 to $42.41; Merck ( MRK), down 18 cents to $34.75; Renovis ( RNVS), up $1 to $14.17; Johnson & Johnson ( JNJ), up 29 cents to $68.51; Amgen ( AMGN), down 13 cents to $58.83; Schering-Plough ( SGP), down 5 cents to $20.80; Teva ( TEVA), down 8 cents to $31.59; and Genentech ( DNA), down $1.41 to $72.99.