Calcium and magnesium deficiency and C3 fraction of complement

: The third (C3) and fourth (C4) components of complement and C3 proactivator (C3PA) were determined in 55 children with low serum levels of calcium and magnesium and 30 normal children. The concentrations of serum C3, C4 and C3PA were significantly reduced in children with double deficiences of calcium and magnesium. There were significant correlations between calcium and C3 and magnesium and C3PA. The relations between calcium, magnesium and the classical or alternate pathway of complement systems are discussed.