Clinical utility of measuring free thyroxin and free triiodothyronine in serum of critically ill patients by ultrafiltration.

[摘要] Free thyroxin (FT4) measurements by ultrafiltration were compared with results obtained by equilibrium dialysis and commercial RIA methods. In a group of critically ill patients, the mean +/- 2 SD FT4 value by ultrafiltration (26.5 +/- 21.4 ng/L) was higher than in the healthy reference population (19.3 +/- 9.8 ng/L, p less than 0.0001), and correlated well with equilibrium dialysis (23.8 +/- 20 ng/L, r = 0.87). By a two-step RIA method (Clinical Assays), the FT4 value was greater in the critically ill (14.7 +/- 9.6 ng/L) than in the reference population (12.8 +/- 5 ng/L, p less than 0.001) and was also correlated with ultrafiltration results (r = 0.71). FT4 values for the ill patients were lower than for the reference population in two one-step RIA methods (Clinical Assays: 8.6 +/- 7.1 ng/L; Corning Medical: 12.7 +/- 9.4 ng/L), neither of which gave results correlated with ultrafiltration (r = 0.16 and 0.22, respectively). The concentration of free triiodothyronine (FT3), also measured by ultrafiltration, was 4.5 +/- 2.2 ng/L in healthy subjects, 12.5 +/- 14.2 ng/L in hyperthyroidism, 1.7 +/- 2.0 ng/L in hypothyroidism, 2.2 +/- 1.9 ng/L in the critically ill subjects, and 3.8 +/- 0.9 ng/L in pregnancy. Thus, FT4 and FT3 measured by ultrafiltration accurately affects assessment of the thyroid status of the patient except in critical illnesses in which FT3 values are indistinguishable from those in hypothyroidism.

[学科分类] 过敏症与临床免疫学