Variations in plasma protein concentrations in individuals with ulcerative colitis: analytical and biological factors.

Eight plasma proteins were determined in specimens taken every second day during a 14 day period from eleven patients with acute ulcerative colitis. The intra-individual variations in the concentrations of albumin, orosomucoid, haptoglobin, IgG, IgA, IgM and complement factors C3 and C4 were larger than expected in normal persons. A two-way analysis of variance was applied to the normalized protein values to estimate to what extent the observed variations could be explained by analytical errors and the influence of biological factors general to all proteins, such as changes in plasma volume and distribution between plasma and extravascular space. In half the non-operated patients the changes in all proteins could be explained by the above mentioned variations. The individual variations seen in the concentrations of haptoglobin, C4 and IgM occurred at random compared to the clinical state of the disease. Only the operated patients showed a more systematic sequence of protein changes.