Thanks for posting your question on HCM!
I appreciate your concerns regarding the swollen glands.
The data lacking in your question: Age, gender, duration of the problem, any associated symptoms like fever, 
weight loss, sweating, etc.
I have gone through the list of investigations your doctor has requested.
He wants to rule out the possible causes of generalized 
lymph nodes swellings;
Following are some of the important and common causes:
Without any associated symptoms some times  it may be self limiting.
With associated symptoms like fever, 
night sweats, weight loss, 
Infectious mononucleosis, Blood cancers (lymphomas/leukemias), HIV infection, Systemic 
lupus erythematosis.
In the above mentioned causes associated symptoms are present that will help in the diagnosis along with the relevant investigations advised.
Urine analysis and the M/C panel is requested to rule out the involvement of kidneys (specially in suspected systemic lupus erythematosis).
I hope your doubts have been clarified. Please visit your doctor for follow up and the treatment accordingly.
Best of your health.