Serum neopterin and beta 2-microglobulin concentrations in monoclonal gammopathies.

Serum neopterin and beta 2-microglobulin concentrations were investigated in 46 patients with multiple myeloma and in 28 patients with asymptomatic monoclonal gammopathy followed for long periods (median 9.6 years) and showing an absence of evolution. Seventy-two per cent of the patients with multiple myeloma showed beta 2-microglobulin concentrations higher than 3 mg/l with a mean of 6.84 mg/l, whereas all the patients with asymptomatic monoclonal gammopathies had concentrations lower than 3 mg/l with a mean of 1.64 mg/l. Concerning serum neopterin concentrations, 91% of the patients with multiple myeloma had values with in pathological limits (greater than 8 nmol/l) with a mean of 34 nmol/l, whereas all but one of the patients with asymptomatic monoclonal gammopathy had normal values with a mean of 5.19 nmol/l. The differences thus observed in these two groups of patients are highly significant (p less than 0.001). Serum neopterin concentration, unrelated to renal insufficiency, seems to be useful in the differentiation of malignant or benign asymptomatic monoclonal gammopathies.