Abstract
Warfarin anticoagulation has been previously shown to result from inhibition of post-translational synthesis of γ carboxyglutamic acid (Gla) from glutamic acid residues in the vitamin K-dependent clotting factors. This recently discovered amino acid (Gla) is synthesized in the liver and is known to be excreted in urine largely as the free amino acid. Furthermore, previous work indicates that urinary Gla excretion is chiefly derived from prothrombin breakdown and turnover. The purpose of the present study was to monitor urinary Gla excretion in order to detect any significant differences between normal and anticoagulated patients. Fourteen patients were studied. Seven were on stable Warfarin anticoagulation therapy and 6 were controls. One patient was studied postoperatively during initial anticoagulant treatment. Free urinary Gla was measured in 24 hour collections using 2N KOH hydrolysis and automated amino acid analysis. Normal subjects excreted 18-27 micromoles (μM of Gla)/24 hours (hrs) while anticoagulated patients (Prothrombin time range 20-30 sec. control = 12.0) excreted only 2.7-13 μM/24 hrs. Gla excretion in the patient begun on Warfarin dropped progressively during the first 10 days of therapy (128 μM/24 Hrs. to 22 μM/24 hrs.) while Prothrombin time stablized by day 6 (range 19.0 sec. to 22.9 sec) We conclude that urinary Gla excretion is reduced by Warfarin, and that monitoring urinary Gla may prove useful in regulating anticoagulation.
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Levy, R., Lian, J. & Gallop, P. 260 STUDIES ON A NEW COAGULATION PARAMETER: DECREASED URINARY X CARBOXYGLUTAMIC ACID EXCRETION WITH WARFARIN THERAPY. Pediatr Res 12 (Suppl 4), 407 (1978). https://doi.org/10.1203/00006450-197804001-00265
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DOI: https://doi.org/10.1203/00006450-197804001-00265