Cut off changes every year and is dependant on various factors like no.of seats available, no.of candidates appearing for the exam, difficulty of the exam, candidate's categoey and top NEET score. Now you haven't mentioned your Category. However, in 2018, under State Quota:

General Category: 589
SC:450
ST: 300 secured seats in Trivendrum Medical College. Under All India Quota:

General Category: 599
SC: 459
ST: 422

So your score should be atleast 50-75 marks more than the last year's cut off for your category to get a Medical seat.