The calcium and phosphorus in the blood (and human milk) does not
precipitate out. These minerals are maintained in human milk at fairly
constant levels regardless of maternal diet. Precipitates occur in
parenteral solutions because of a variety of factors (i.e., amino acid
concentration, pH, temperature). Although I'm not a biochemist, I would
think the form that these minerals occur in human milk vs. parenteral
solutions effects solubility.
Nancy Hurst, RN, MSN
Texas Children's Hospital