* Q4 operating profit below expectations
* Weak dollar to hurt 2018 results by more than expected
* Former Statoil, BG Group CEO Helge Lund proposed as new chairman
* Shares headed for worst daily performance in a year (adds CEO and analyst comment, background)
COPENHAGEN, Feb 1 (Reuters) - Novo Nordisk operating profit fell short of expectations in the fourth quarter as it felt the effects of price pressure in the United States and it warned that a weak dollar would hit earnings this year more than expected.
Shares in Novo traded 5 percent lower by 0935 GMT after the Danish drugmaker suffered its second setback this week, having lost out to France's Sanofi over a deal to buy Belgian biotech company Ablynx.
Novo, the world's biggest insulin maker, had been seeking to broaden its blood product line-up in its biopharmaceuticals division, which makes up nearly 20 percent of group revenue.
Novo also said Chairman Göran Ando will step down at a shareholder meeting in March, and that current board member Helge Lund, former Statoil and BG Group chief executive, was the candidate to replace him.
The firm posted a quarterly operating profit of 10.05 billion Danish crowns ($1.7 billion) on revenue of 27.99 billion crowns, down 10 percent from a year earlier and below an average 10.38 billion crowns forecast in a Reuters poll of analysts.
"Overall, the results are to the weaker side. Their insulin business looked challenged in the quarter, with both Tresiba and modern insulins performing worse than expected," said Sydbank analyst Soren Lontoft.
The U.S. market accounts for around half of Novo's sales and Chief Executive Lars Fruergaard Jorgensen warned conditions were tough there, with drug prices a contentious political issue.
"There is a continued pressure on pricing in the United States," Jorgensen told a conference call.
He added that higher rebates to customers in the United States towards the end of 2017 "took growth in the fourth quarter a bit down."
Novo reiterated its 2018 sales growth forecast of 2-5 percent and operating profit at 1-5 percent growth, both in local currencies.
However, 2018 sales and operating profit measured in Danish crowns will be hit by a weaker dollar, Novo said.
Sales growth is expected to be 7 percentage points lower than in local currencies, compared with a previous guidance of 3 percentage points lower. Operating profit growth is expected to be 10 percentage points lower, compared with its previous guidance of percentage points lower.
Novo Nordisk said earlier this week it will continue to hunt for promising assets to refill its blood products business, after missing out on Ablynx.
"We could not see the level of value that the transaction took place at," said Novo Chief Financial Officer Jesper Brandgaard.
Novo said Brandgaard will step down as CFO later this month to be replaced by Karsten Munk Knudsen, currently senior vice president of corporate finance.
Brandgaard will continue as executive vice president responsible for Novo's biopharm business and legal affairs.
Swiss drugmaker Roche forecast on Thursday that U.S. tax changes would mean its profit growth outstrips sales in 2018.
Novo said it expects to benefit from the U.S. tax changes by around 1 percentage point. ($1 = 5.9976 Danish crowns)
(Reporting by Jacob Gronholt-Pedersen; Editing by Adrian Croft and Keith Weir)