Is Hemaglobin a Tetrimer?

My globin is exactly one quarter the size of a hemoglobin, right? I mean, that can't be a coincidence, no. And it's this difference that really has huge implications for the sive sevin coefficient. Free mioglobin is much more able to make its way through the glamerlus, access the tubules and cause pigment nephropathy. It actually turns out that hemaglobin exists not just as tetrimers, but also as dimers.