UPDATE 2-United Therapeutics posts surprise Q4 loss, shares down

* Q4 loss/shr $0.06 vs est EPS $0.28

* Q4 rev $108.9 mln vs est $104.1 mln

* Shares down 7 pct (Recasts lead, adds details, share movement)

Feb 16 (Reuters) - United Therapeutics Corp (UTHR.O) reported a surprise fourth-quarter loss, hurt by higher expenses, sending its shares down as much as 7 percent.

However, revenue rose 44 percent to $108.9 million, beating analyst estimates of $104.1 million, due to a rise in number of patients prescribed Remodulin for the treatment of pulmonary arterial hypertension (PAH) and the launch of PAH drugs Tyvaso and Adcirca.

For the quarter, the company posted a net loss of $3.3 million, or 6 cents per share, compared with a net loss of $82.1 million, or $1.73 a share, a year earlier.

Analysts had expected a profit of 28 cents a share, according to Thomson Reuters I/B/E/S.

Excluding share-based compensation, amortization and other charges, the company earned 62 cents a share.

Total selling, general and administrative expenses, including share-based compensation of $15.8 million, rose to $56.6 million from $21.9 million in the year-ago period.

PAH is a life-threatening disease that affects the blood vessels in the lungs and is characterized by increased blood pressure in the blood vessels leading from the heart to the lungs, known as the pulmonary arteries.

The elevated pressure in the pulmonary arteries strains the right side of the heart as it pumps blood to the lungs leading to right heart failure and death.

Shares of the company, which develops and markets drugs for cardiovascular and infectious diseases and cancer, were down 6 percent at $56.50 in morning trade on Nasdaq. They touched a low of $55.86 earlier in the session. (Reporting by Shailesh Kuber in Bangalore; Editing by Vinu Pilakkott and Aradhana Aravindan)