Is egfr value of 77 in 56 years old man something to be concerned about?

EGFR: If you have a normal urinalysis & microscopic examination, normal BUN & serum creatinine, your eGFR, even though it's less than 90, probably means your kidneys are functioning normally. Other tests for kidney function include creatinine clearance and cystatin C which is considered more accurate than a creatinine based formula. A nephrologist could advise you further.