** Shares of lab operator Quest Diagnostics DGX.N rise 6.7% to $172.67 premarket

** DGX posts Q1 adj. profit of $2.21 per share helped by robust demand for its diagnostic tests, beating analysts' estimates of $2.15, according to data compiled by LSEG

** Company reports Q1 revenue of $2.65 billion vs estimates of $2.63 billion

** Company continues to expect annual adj. profit in the range of $9.55 and $9.80 per share vs estimates of $9.68

** DGX maintains its annual net revenue forecast in the range of $10.70 billion to $10.85 billion vs estimates of $10.78 billion

** As of last close, DGX had risen 7.3% YTD

(Reporting by Siddhi Mahatole)

((siddhi.mahatole@thomsonreuters.com))