Among the nation's large urban areas, the top eight in population growth from 1980 to 1986 were in the South and West, led by Phoenix, which had a 26 percent increase in population, the Census Bureau reported yesterday.

The bureau studied 281 metropolitan areas, which consist of a core city or heavily settled suburb and its surrounding areas. Among those with at least 1 million population, those with fastest growth were: Phoenix; Dallas-Fort Worth, 25 percent; Atlanta, 20 percent; San Antonio, 19 percent; Tampa-St. Petersburg, 19 percent; San Diego, 18 percent; Sacramento, 17 percent, and Houston, 17 percent.

The nation as a whole grew by 6.4 percent. The figures show that the Washington metropolitan area grew by 9.6 percent during the period. As of July 1, 1986, the area population was 3,563,000, making it the 10th largest U.S. metropolitan area. The metropolitan area includes not only the District of Columbia, Montgomery, Arlington, Fairfax and Prince Georges counties plus the cities of Alexandria, Fairfax and Falls Church, but also a number of more distant areas such as Calvert, Charles, Loudoun and Prince William counties.

Among metropolitan areas, those losing population through most of the 1980s were mostly in the industrial Midwest and Northeast.

Five metropolitan areas with populations of more than 1 million had net losses from 1980 to 1986: Buffalo, 4.9 percent; Pittsburgh, 4.4 percent; Detroit, 3.2 percent; Cleveland, 2.4 percent, and Milwaukee, 1.2 percent.

Looking at all 281 U.S. metropolitan areas regardless of size, the bureau found that 10 of the 11 fastest-growing areas were in Florida and Texas. All of these had fewer than 1 million population. Their growth rates were from 29 to 41 percent.

Those in Florida were: Naples, Ocala, Fort Myers-Cape Coral, Fort Pierce, Melbourne-Titusville and West Palm Beach. Those in Texas were: Austin, Midland, Bryan-College Station and McAllen-Edinburg-Mission. The 11th was Anchorage.