The `Angels` singer previously revealed he has an undisclosed hormone condition which means he lacks the steroid hormone which is vital for the development and health of the male reproductive organs.
Robbie was diagnosed with the rare imbalance last year and although he is still taking medication for the problem he has learned to accept the treatment as a part of his life.
When asked if he has the testosterone level of a 100-year-old man, he said: "No, I have none. I take meds and inject myself once a week. It`s just something I had, I take care of and everything is cool. It`s part of the story, it`s part of why I`ve been, where I`ve been and who I am."
Robbie is happily married to actress Ayda Field and the pair are expecting their first child together, a daughter, in a matter of weeks.
The British pop star admits it was a strange experience writing his new solo album `Take The Crown` because he is so happy and most of his previous tracks focused on negative feelings.
In an interview with GQ magazine, he said: "Most of my songs are about feeling rubbish. I thought, `What am I going to sing about now I`m happy? I am going to sing about great happiness!`
"Gary Barlow came up to me and said, `You have never written a love song,` so I did just that. I`ve managed to write a happy album."