The parameter that changes with advancement of age

The hemoglobin concentration, red blood cell count, and hematocrit value began to decrease in men in their sixth decade and in women in their seventh decade and the change was more prominent with advancing age, especially in men. The white blood cell count and platelet count tended to decrease with advancing age. Ref: guyton and hall textbook of medical physiology 12 edition page number: 116,117,118