The journalist usually fronts the show from Thursday to Saturday each week alongside her co-star Charlie Stayt.
She told her Radio 5 Live listeners: "Right now as I sit here talking to you: I am in pain. Constant, nagging pain. In my uterus. Around my pelvis. Sometimes it runs down my thighs. And I’ll have some level of pain for the entire show and for the rest of the day until I go to sleep."
Naga explained that she lives "every day on painkillers" and said that she does not wear "light-coloured trousers" while presenting BBC Breakfast as she is "so afraid" of leaking while on her period.
Detailing a time that she almost passed out while hosting the show, she said: "I just said, 'I have to leave'. And I went to the loo and I thought I was going to pass out, but I threw up and then just came back."
Speaking about the crippling pain she experienced the weekend before, she revealed that her husband James called an ambulance in the middle of the night. "I was writhing around and moaning and screaming in pain. Eventually, I got to sleep after about 45 minutes. And then it happened again in the middle of the night and we had to call an ambulance because I couldn’t be moved. And I was just screaming.
"All I remember saying is: 'If the ambulance comes (which it didn't), do not let them give me a full hysterectomy'. Because that is the only cure to get rid of it," she said.
On Tuesday, the 48-year-old shared her first Instagram photo since revealing her diagnosis, sharing an update with her fans. Posting a selfie showing the star looking fresh-faced, she wrote in the caption: "It's not actually that warm out there this morning! Did a short run anyway to get going. Feeling better for it and [sweating emoji]."
Promoting her 5 Live afternoon show, she added: "I'll be in your [ear emoji] later @bbc5live 11am-1pm. Talking more about #adenomyosis and how to raise awareness and ensure better care and diagnosis for those who suffer with it."
Fans were quick to praise the broadcaster in the comments section, with many thanking her for raising awareness of the condition. One person wrote: "Excellent work!! Will be listening - great to see a public profile raising the awareness of adenomyosis. So much work still needs to be done in the UK!" while another added: "Thank you so much for helping us spread awareness on this debilitating condition."
Don't want to miss a story? Sign up to our What to Watch newsletter and get the heads-up on the shows and films everyone’s talking about.