WASHINGTON — As much as the Mets are aware of the need to build up Noah Syndergaard’s innings, they plan to be sensible about the issue once he returns to the rotation.

It’s expected Syndergaard will be removed from the disabled list Wednesday to face the Nationals, after he missed his last start with hand, foot and mouth disease. Syndergaard, who previously missed seven weeks with a strained index finger, has pitched only 74 ²/₃ innings this season.

Ideally, the Mets can receive another 60-65 innings from Syndergaard toward his buildup for 2019, but “common sense” will be employed by the club to ensure he isn’t pushed too hard in trying to hit a goal.

If Syndergaard doesn’t build up enough this season it’s possible he could face an innings limit next year. Syndergaard missed most of 2017 with a torn lat and manager Mickey Callaway acknowledged the right-hander likely would have faced an innings limit this year if he hadn’t spent so much time on the DL.

The Mets will open a two-game series against a disappointing Nationals team that could be in sell mode headed toward the 4 p.m. non-waiver trade deadline on Tuesday.

A report Monday indicated the Nationals had discussed Bryce Harper with the Indians, but such a deal appeared unlikely.

Relievers Ryan Madson, Shawn Kelley and Kelvin Herrera have all been mentioned in recent days as pieces the Nationals could move. Daniel Murphy is headed to free agency after the season and has been a disappointment with a .701 OPS coming off microfracture surgery in his knee, but could potentially help a contender in need of a bat.

The Nationals (52-53) have been baseball’s biggest disappointment this season and will begin play six games behind the Phillies for the NL East lead.

Todd Frazier’s rehab assignment will continue Tuesday for Single-A Brooklyn. The Mets are hopeful the third baseman will return from the disabled list by this weekend.

Austin Jackson has played for eight different major league teams over the last five seasons, which ties him with Tyler Clippard for the highest total over that stretch, according to the Elias Sports Bureau. The Mets signed Jackson on Friday. Clippard pitched for the Mets in 2015.