At your father's age it would be most prudent on his part to first get his natural Testosterone and Estrogen levels tested by a qualified physician. Getting Estrogen levels tested is important because as we age our bodies produce more aromatase enzyme, and thus produce more Estrogen. High Estrogen levels in older men is now considered to be a predominate cause of benign prostatic hyperplasia (BPH), (enlarged prostate), and prostate cancer.