UPDATE 2-HCA Healthcare's quarterly profit misses on weak patient volumes

(Adds details, analyst comments, shares)

July 25 (Reuters) - Hospital operator HCA Healthcare Inc's profit missed analysts' estimate for the second straight quarter, hurt by higher expenses and weaker-than-expected patient volumes and lowered full-year earnings forecast.

Shares of the largest U.S. for-profit hospital operator fell 3.3 percent to $83.23 in early trading, while smaller rivals Community Health Systems Inc and Tenet Healthcare Corp also traded lower.

Hospital operators' stocks have been volatile as Republicans attempt to dismantle the Affordable Care Act, popularly known as Obamacare, raising concerns that a healthcare overhaul will curtail the benefits hospitals have gained from expanded insurance coverage.

President Donald Trump made a last-ditch plea on Monday to U.S. Senate Republicans to "do the right thing" and fulfill campaign promises to repeal and replace Obamacare. The Senate will vote on Tuesday on whether to open debate on an overhaul of the law.

Net income attributable came in at $657 million, or $1.75 per share, in the second quarter ended June 30, compared with $658 million, or $1.65 per share, a year earlier.

Analysts' average estimate was $1.80 per share, according to Thomson Reuters I/B/E/S.

The company said its equivalent admissions, which include patients who stay in the hospital overnight and those who are treated on an outpatient basis, rose 1.3 percent in the quarter.

Mizuho Securities USA analyst Sheryl Skolnick said it was now clear that HCA needed external growth to augment slowing organic growth.

"And that doesn't make us comfortable given pressures on same-store utilization rates."

HCA has been scooping up hospitals from Community Health and Tenet Healthcare as the hospital operator looks to bulk up for growth.

HCA said salaries and benefits, supplies and other operating expenses rose 4.6 percent to $8.66 billion.

The company, which operates 172 hospitals and 119 freestanding surgery centers, reported a 4 percent growth in revenue at $10.73 billion, but it was below analysts' estimate of $10.85 billion.

Evercore ISI analysts said the magnitude of the volume weakness was still a surprise and expected the stock to sell off.

HCA now expects earnings per share for the year in the range of $7.00 to $7.30, down from $7.20 to $7.60 it previously forecast. (Reporting by Ankur Banerjee in Bengaluru; Editing by Amrutha Gayathri)