I'm at a loss how to help. Boyfriend possibly in renal failure

I'm not sure of this is the right place but I didn't know where else to turn

I've been in a LDR with my boyfriend for four months. We see each other once a month.

Thursday he went to the doctor, he has diabetes. Based on his urinalysis the doctor believes his kidneys are failing. Blood work is next week, I cannot imagine what he is going through right now.

I'm struggling with how to help. He tends to pull back and close off when he is going through something and I'm attempting to be respectful. At the same time, I'm not going to sit back and let him close off completely. I've message him that I wished there was something I could do or say to make it easier. And that the only thing I can do is say I love you and I'm here. How do I be supportive? Especially since I'm 1000 miles away?

How would you check in as "how are you?" Or "you doing ok?" Doesn't seem appropriate. Luckily I fly out for the weekend on Friday.