My 92-year-old mother's left hand is double the size of the right. It happens at night and goes down during the day. What does this mean?

Shane 1124 - Absolutely, a mastectomy on that side could cause swelling from edema of the arm’s lymph nodes. Also something wrong with blood vessels in the arm or shoulder area. If a woman has had a mastectomy then the arm on that side shouldn’t wear tight sleeve cuffs, anything restricting blood or lymph system.

Don’t let the doctors poo-poo it away like they did to my mom until she’s in heart failure before they hospitalize her! At least five so called doctors ignored my mom’s leg with was grotesquely swollen! It is CHF. She was treated and it’s much better!!

She could also have some sort of blood vessel blockage specifically a vein. Has she ever been hospitalized and a catheter placed in her chest or neck? Many times once the catheter is out the vessel can narrow or spasm. Note the color and temperature of the arm. Or it could be a blockage in a lymph node, has she had a mastectomy?
She needs to be seen by her PCP. They can order tests to check for the above.

I agree with Susan, take Mom to her primary doctor.

Hopefully it is something as simple as too tight of clothing that Mom wears at night while lying on her left side. That happened to my Dad.... one time he didn't take his socks off before going to bed and woke up with one knee swollen almost double the size.... turned out the sock on that leg the elastic was too tight. Went through his dresser and threw out any socks that had similar elastics.

Mom should see her physician ASAP about this. She may have an infection or something more serious going on. Don't give her anything until you discuss with her dr.