2,3-Dinor metabolites of thromboxane A2 and prostacyclin in urine from healthy human subjects: diurnal variation and relation to 24 h excretion

• Published in: Clinical science (1979) Vol. 83; no. 4; pp. 461 - 465
• Main Authors: Wennmalm, Å., Benthin, G., Granström, E.F., Persson, L., Winell, S.
• Format: Journal Article
• Language: English
• Published: 01.10.1992
• ISSN: 0143-5221; 1470-8736
• DOI: 10.1042/cs0830461

1. Urinary levels of the 2,3-dinor metabolites of thromboxane A2 (2,3-dinor-thromboxane A2, Tx-M) and prostacyclin (2,3-dinor-6-keto-prostaglandin F1α, PGI-M) are frequently analysed as indices of platelet and endothelial activity and interaction in vivo. Despite this, little is known about the possible diurnal variations in urinary Tx-M and PGI-M in healthy human subjects, and how the urinary levels of Tx-M and PGI-M in single samples reflect their respective 24 h excretion rates. We addressed this by determining Tx-M, PGI-M and creatinine in consecutive portions of urine collected during 24 h in 15 healthy non-smoking subjects. 2. The total 24 h excretion of Tx-M and PGI-M did not differ between men (223 ± 31 and 132 ± 27 ng, respectively) and women (215 ± 44 and 127 ± 29 ng, respectively). Neither the excretion of Tx-M nor that of PGI-M displayed any significant diurnal variation. 3. The excretion of Tx-M during a 3 h period and the Tx-M/creatinine ratio in a urine sample accurately reflected the 24 h excretion of Tx-M (correlation coefficient ranges 0.74–0.94 and 0.74–0.86, respectively). The excretion of PGI-M during a 3 h period and the PGI-M/creatinine ratio in a urinary sample were accurate measures of 24 h excretion of PGI-M (correlation coefficient ranges 0.76–0.94 and 0.72–0.83, respectively). Urinary Tx-M and PGI-M expressed as simple concentrations were poor indices of their respective 24 h excretion. 4. We conclude that time-related excretions of Tx-M and PGI-M may be the best indices ex vivo of the cardiovascular formation of thromboxane A2 and prostacyclin, but that urinary creatinine-related concentrations of Tx-M and PGI-M in a urine sample are accurate measures as well.