We consider a protocol for the two-time measurement ofentropic observables in quantum open systems driven out of thermal equilibrium bycoupling to several heat baths. We concentrate on the Markovian approximation ofthe time-evolution and relate the expected value of the so defined entropyvariations with the well-known expression of entropy production due to Lebowitzand Spohn. We do so under the detailed balance condition and, as a byproduct, weshow that the probabilities of outcomes of two-time measurements are given by acontinuous time Markov process determined by the Lindblad generator of theMarkovian quantum dynamics.