Taurine deficiency after intensive chemotherapy and/or radiation.

Taurine, a nonessential amino acid (AA), is the most abundant free AA in the intracellular space. We measured plasma AA concentrations in 36 patients 7-28 d after intensive chemotherapy and/or radiation. Plasma taurine concentrations were uniformly low in all patients (20.0 ± 6.4 L, ... ± SD). Plasma taurine in 11 healthy volunteer control subjects was 45.0 ± 20.3 (P < 0.001). Other AA concentrations, specifically those of precursor AAs methionine and cystine, were normal. We prospectively measured plasma AA concentrations in 12 patients before starting and 6-10 d after completing intensive cytotoxic treatment. Values before treatment were 37.2 ± 1 1.6, 109.6 ± 30.7, and 18.5 ± 4.8 for taurine, cystine, and methionine, respectively, and were 24.3 ± 6.0, 1 11.2 ± 23.8, and 24.0 ± 14.5 after treatment. Pretreatment plasma taurine correlated directly with the magnitude of decrease in plasma taurine during cytotoxic treatment (n = 12, r = 0.85, P < 0.01). Intensive cytotoxic chemotherapy and/or radiation leads to a reduction in plasma taurine concentrations without any change in its precursor AAs, methionine and cystine. The clinical relevance of plasma taurine depletion will need further study. [ABSTRACT FROM AUTHOR]