The defender has managed 39 appearances for Los Blancos this season, during a campaign which has also seen him score 10 goals for the club.
They are also out of this season's title race with the club currently on 60 points in third position, with 13 points separating them from leaders Barcelona with just seven games left to play.
Zinedine Zidane's side will now have to play their upcoming fixtures without their club captain as he looks to overcome an issue with his left calf muscle.
Madrid confirmed on Friday that Ramos has "a grade one injury in the left soleus" but they also gave no timetable for his return.
Calf issues aren't uncommon for Ramos, with the defender have missed a stint during January 2018 with a similar problem.
However, this is set to be his first absence from the squad due to injury this season.
While their final objective of securing Champions League football doesn't currently look under threat with Madrid currently holding an11-point gap over fifth-place Sevilla, it doesn't bode well for a strong end to the season.
Zidane's men are just two points behind rivals Atletico Madrid in second, and pride remains at stake between the two sides as to who will finish the highest.
Diego Simeone's men finished above Real last year, and Zidane will be hopeful of gaining revenge this season.