It's been a pretty good year for Quest Diagnostics (DGX -1.28%) so far. The stock is beating the performance of the S&P 500 despite Quest's posting mixed second-quarter results in July.

Investors found out if the good times would keep rolling when Quest Diagnostics reported its third-quarter results before the market opened on Tuesday. Here are three key things you'll want to know about the company's latest quarterly update.

Man in white coat in hospital hallway with arms crossed while holding a stethoscope

Image source: Getty Images.

1. Slightly better-than-expected revenue growth

Quest Diagnostics announced Q3 revenue of $1.96 billion. This represented a 3.5% year-over-year increase. It also narrowly beat the consensus Wall Street revenue estimate of $1.94 billion. 

The diagnostics information services company's Q3 performance was significantly better than the 1.8% year-over-year revenue growth reported in the second quarter. CEO Steve Rusckowski said that Quest's "expanded network access" was a key factor in this improvement.   

2. Even more impressive earnings beat

Quest reported net income of $215 million, or $1.56 per diluted share, based on generally accepted accounting principles (GAAP). This reflected a 2.8% increase from the prior-year period on a per-share basis.

The company announced non-GAAP (adjusted) earnings per share (EPS) of $1.76, up 4.8% year over year. This figure handily beat the average analyst estimate of Q3 adjusted EPS of $1.71.

Rusckowski stated that Quest's "laser focus on driving operational excellence" helped enable growth. The company kept operating costs under control. Quest achieved solid earnings growth despite a higher income tax expense.

3. Improved full-year outlook

With its Q3 revenue and earnings beats, Quest Diagnostics boosted its full-year 2019 guidance. Rusckowski said, "Based on our progress to date we have updated our outlook and are well positioned to meet our commitments for the rest of the year."

The diagnostics information services leader now anticipates revenue of $7.72 billion. That's a little higher than the midpoint of Quest's previously projected range of revenue, which was between $7.6 billion and $7.75 billion.

The company also expects 2019 GAAP EPS will be between $5.48 and $5.53. Previously Quest's full-year 2019 guidance called for GAAP EPS of "greater than $5.29."

Quest now projects adjusted EPS for full-year 2019 will be between $6.45 and $6.50. Its earlier guidance estimated full-year adjusted EPS of "greater than $6.40."

The bottom line

Quest Diagnostics continues to make solid, although not spectacular, improvement. Growth investors won't be overly impressed with the company's relatively modest revenue and earnings increases in the third quarter. However, Quest remains a dividend stock that some investors might like. Its dividend currently yields a little over 2%. As long as the company keeps delivering performances as it did in the third quarter, those nice dividends will keep on flowing.