What can I do for my thinning hair following surgery for a growth hormone and prolaction pituitary adenoma in winter 2015?

In my opinion, it is important to differentiate between a telogen effluvium  hair loss,  and diffuse alopecia areata. A hair expert will look at the pattern of hair loss, the type of hair present on the scalp, a pull test and possibly a biopsy and blood work to determine the diagnosis. Both alopecia areata and telogen effluvium should be time-limited in many cases  (6 to 12 months). Treatment will vary depending upon the diagnosis. Hope this helps. Good luck.

This is a complex history and there's only a few generalizations I can offer. It takes 9 months to see changes with minoxidil. Information given at three months does not have a lot of significance. If hair loss is related to surgery or hormonal fluctuations, it takes a year to reverseHair loss in a 61 year old with the history given is rarely if ever from a single causeDiffuse alopecia areata is one of the most challenging diagnoses, so I'm always a bit skeptical of the diagnosis. I'd say 50 % of the referrals I get for diffuse alopecia areata are not diffuse alopecia areata. Yes, biopsies can be wrong.Steroid injections only help if it's diffuse alopecia areata.Laser can help multiple causes of hair loss, so can minoxidil.All in all,  you need a comprehensive evaluation of your hair loss by a dermatologist. 

Telogen efflivium may continue around 1 year , so after that time interval between stress and loss, hair may regrowth again.During that certain time  PRP, LLLT treatments may help to regrowth of hair fastly . If after 1 years you have still alopecia/ hair loss than you may try to get an hair restoration surgery .

You are not a candidate for hair transplants with alopecia areata because hair placed into these active areas get attacked by your immune system but you may very well be a good candidate for scalp miropigmentation (SMP) which is a non-surgical treatment for hair loss that works very well. Please send pictures to me so I can ascertain if SMP will work for you.  Below in the web reference is an example of a patient treated with alopecia areata