Doctors often count the amount of lymphocytes in a person's blood to see if he or she has certain illnesses. Why would this be a useful test ?

Molecules like glucose and amino acids are not lipid soluble, so cannot cross the cell membrane by simple diffusion. instead, they are shuttled across by carrier proteins in the membrane from high to low concentration. does this process require energy from the cell? this is an example of what type of molecular movement?