I am 50 years old and had my first psa test at 45 which was 0.72. all tests since then varied between 0.62 and 0.84, fluctuating from year to year. yesterday i got a reading of 0.90 and got really worried. is there any big concern about it ?

They demonstrated that the serum PSA concentrations correlated directly with age and the recommended upper limit of normal serum PSA levels for white men are: 2.5 ng/ml for 40-49 years, 3.5 ng/ml for 50-59 years, 4.5ng/ml for 60-69 years, and 6.5ng/ml for 70-79 years. Your level is still in the normal range. Talk to the doctor who ordered the test as s/he knows your health better.

All tests icluding the PSA can vary a little. If there is no increase in a step wise manner and the rectal exam of the prostate is normal and there is no family history of prostate or ovarian cancer then follow up is fine as overwhelmingly with PSA under 1 prostate cancer is extremely rare