The incidence of protein C deficiency in thrombosis-related portal hypertension.

OBJECTIVE: To know the incidence of protein C deficiency associated with noncirrhotic, thrombosis-related portal hypertension. METHODS: Thirty-six patients were studied who had thrombosis-related portal hypertension diagnosed by means of hepatic venography or abdominal echocardiography or during abdominal surgery. Liver disease was excluded in 20 patients based on normal liver function tests and normal histology on liver biopsy. At the time of protein C assays, these patients were not receiving oral anticoagulation, and, in those recently diagnosed, the assays were performed more than 14 days after the last thrombotic event. Antigenic and functional assays for protein C were performed by ELISA and chromogenic assay, respectively. RESULTS: We found 11 patients with protein C deficiency who had a median age of 28 yr (range 19-55 yr) at time of diagnosis. Five patients had a history of systemic thromboembolism, and upper GI bleeding was the most frequent symptom related to portal hypertension (six cases). Antigenic protein C levels were measured in nine of the 11 patients (mean 31.88%, range 10-49%). Functional protein C level was assayed for all 11 patients (mean 40.90%, range 15-58%). After diagnosis, all patients received oral anticoagulants (ideally International Normalized Ratio: 2-3). CONCLUSION: We suggest that protein C screening should be performed in patients with thrombosis-related portal hypertension.

[Reference values for protein C activity in healthy adults in Mexico]. / Valores de referencia de la activadad de proteína C en adultos sanos en México.

Protein C (pC) is a natural-occurring anticoagulant and its acquired or hereditary deficiency has been associated with thrombosis. For its screening, technics that appraise both its plasmatic concentration and biological activity are used. The quantitative deficiency is important, but some characteristics of pC activity (pCA) suggest an essential role of the functional deficiency. Because reference levels have not been previously described in Mexico, we report here the results of a pCA assessed by a chromogenic assay in 88 adult healthy mexican people between 15 and 69 years of age. The pCA values at the 2.5 and 97.5% percentiles in our population were 75 and 137% in normal plasma. Functional disorders of this protein have been described in the presence of normal pC quantitative levels and, therefore, there are individuals with low pC concentrations and a normal pCA without thrombosis. These data suggest that the pCA could be a more important screening test than the quantitative determination as the first step in the study of a possible deficiency state of protein C.

[The international normalization ratio in the monitoring of oral anticoagulant therapy]. / El cociente de normalización internacional en la vigilancia de la terapia anticoagulante oral.

Oral anticoagulants are employed very frequently in the prophylaxis and treatment of several diseases. For their optimal effectiveness, many vigilance schedules have been proposed but none has proved to be 100% effective. The international normalization ratio (INR) can be a safer way to monitor oral anticoagulation, and our objective was to determine its clinical usefulness. A prothrombin time test (PT) was carried out by means of either a chromogenic or a coagulometric method, and an INR was obtained using the ratio of the PT patient/PT control elevated to an exponential given by the international sensitivity index (ISI) of our thromboplastin. Our objective was to maintain our patients in a therapeutical INR range between two and three. We present our experience with 77 patients and 810 results during an 18 months period. We observed 26 cases of hemorrhage and three of thrombosis. In all these cases, the INR was out of the desired therapeutical range. No deaths occurred in our patients. Our analysis showed a significative disagreement between the INR and the prothrombin time ratio (PTR) but a better correlation with hemorrhage and thrombosis was seen with the INR than with the PTR. Our experience supports the use of INR in the clinical vigilance of oral anticoagulation as a useful method.