Could my gynecomastia because of a kidney tumor?

Unlikely. Some adrenal tumors that interact with the pituitary gland might be. The adrenal gland is attached to the upper pole of the kidney but is distinct in function from the kidney.
No. Not from a primary kidney tumor but be careful- is it an adrenal cancer overlapping and involving the kidney instead - your doctor should know.
Unlikely. Gynecomastia can develop in so called "para-neoplastic syndromes" but in general that is not the case. A complete endocrinologic and physical examination is necessary. I certainly would hope that a kidney tumor is not in the background.

Related Questions

How do I know my gynecomastia is based off of hormones versus a kidney tumor?

Not kidney. Kidney tumors do not produce gynecomastia. The adrenal gland is next to the kidney and very rarely produces female hormones. Gynecomastia is common - feminizing adrenal tumors are exceedingly rare. Read more...
Don't know. Kidney tumors are rare. Have you been diagnosed with one? Gynecomastia developing from kidney disease is usually due to renal insufficiency, not a tumor. More commonly it's from a relative increase in estrogen. Visit gynecomastia.Org, a great forum. Or see my photo gallery at drgeorgepope.Com. Read more...

How would I be able to tell my gynecomastia is based off of hormones and not a kidney tumor?

See an endocrinologi. Kidney rumors are unlikely to cause gynecomastia. Most of gynecomastia patients have normal hormone levels. Some could be related to a particular testicular tumor. An ultrasound of the testicles should be performed to rule it out. Read more...
Hormone analysis. Your medical physician can do blood tests to make sure you do not have a tumor causing your breast to grow. Read more...