UPDATE 1-Gerdau cuts 5-yr investment plan, misses profit view

* Net income at 143 mln reais misses poll estimate

* Decision to cut investments follows weak outlook

* Output, sales, revenue underperform in quarter

SAO PAULO, Feb 21 (Reuters) - Gerdau SA cut its five-year investment plan by 17 percent, as the world's No. 2 maker of steel for builders faces global economic uncertainty and slumping profits.

Planned capital expenditures for its steel and mining units were trimmed to 8.5 billion reais ($4.3 billion) for the 2013-2017 period, from 10.3 billion reais for the 2012-2016 period, the Porto Alegre, Brazil-based company said on Thursday in a securities filing along with fourth-quarter results.

"Considering the uncertainties clouding the global economic scenario, Gerdau is now turning more selective on the evaluation of future capital expenditure plans," it said.

Declining output as well as stagnant sales drove fourth-quarter profit at Brazil's largest steelmaker down about 65 percent from the prior three months. Profit fell for the second straight quarter, along with operational profitability and other efficiency indicators.

Net income tumbled 70 percent from the year-earlier period to 143 million reais, missing the 242 million reais estimate in a Thomson Reuters poll of five analysts.

Mills in Brazil are facing their worst crisis in years as a strengthening local currency, the rising cost of wages and raw materials and competition from imports hamper their ability to stay competitive. More than two years of economic stagnation in Latin America's largest economy has added to the industry's woes.

Output of raw steel fell for a second straight quarter to 4.186 million tonnes, down 12 percent from the prior three months. Sales dropped 9.6 percent as its Brazil, Latin America, North America and specialty steel segments posted disappointing results.

Net revenue fell to the lowest level in five quarters, tumbling 8.5 percent to 8.99 billion reais. The cost of goods sold slipped 7.6 percent, underscoring efforts by Chief Executive André Gerdau-Johannpeter to tame the impact of rampant cost and raw material inflation in Brazil as well as rising wages on the company's home turf.

Earnings before interest, taxes, depreciation and amortization (EBITDA) dropped about 14 percent to 891 million reais, and were below the analysts' estimate of 928.8 million reais. EBITDA fell to 9.9 percent of revenue, the lowest margin in at least three years.

EBITDA per tonne produced, a measure of operational profitability at steel mills, fell to 213 reais in the fourth quarter from 218 reais in the prior period and 217 reais a year earlier.

Management plans to discuss fourth-quarter earnings at a conference call later on Thursday.