Monitoring of the thromboxane A₂/prostacyclin ratio in the urine of patients with retinal vascular occlusion through the low-dose-aspirin therapy using the gas chromatography/selected ion monitoring method

We determined the levels of the stable urinary metabolites of thromboxane A₂ and prostacyclin, 11-dehydro-thromboxane B₂ (11-dehydro-TXB₂) and 2,3-dinor-6-keto-prostaglandin F(1α) (2,3-dinor-6-keto-PGF(1α)) in patients with retinal vascular occlusion (RVO) to elucidate the change of the thromboxane A₂/prostacyclin (TX/PGI) ratio with this disease and the effect of low-dose-aspirin therapy. 11-Dehydro-TXB₂ and 2,3-dinor-6-keto-PGF(1α) were converted to 1-methyl ester-propylamide-9,12,15-tris-dimethylisopropylsilyl ether derivative and 1-methyl ester-6-methoxime-9,12,15-tris-dimethylisopropylsilyl ether derivative, respectively, and applied to a gas chromatography/selected ion monitoring. The average level of 11-dehydro-TXB₂ in 30 patients with RVO was 1038 ± 958 pg/mg creatinine. It was significantly higher than that of 27 healthy volunteers, which was 616 ± 294 pg/mg creatinine (p < 0.05 with unpaired t-test). However, 2,3-dinor-6-keto-PGF(1α) levels were not significantly different between these two groups. The average ratio of TX/PGI in the RVO patients was 32 ± 26 and it was significantly higher than that of healthy volunteers, 17 ± 10 (p < 0.01). Patients with central retinal artery occlusion or branch retinal artery occlusion showed greatly high 11-dehydro-TXB₂ levels and TX/PGI ratios, although the number of patients was limited in the current study. After the administration of low-dose aspirin (40 mg/day) for about 1 month, the TX/PGI ratio decreased to around the normal level. Following the levels for up to 10 months, they also remained at the normal level. These observations suggested that the 11-dehydro-TXB₂ levels and the TX/PGI ratio reflect the pathological conditions of RVO and are useful markers of the treatment. Copyright (C) 1999 Elsevier Science Inc.