Plasma cross linked fibrin degradation products in pulmonary embolism.

Plasma concentrations of cross linked fibrin degradation products, a marker of intravascular thrombosis and fibrinolysis, were measured in 495 patients with suspected pulmonary embolism referred for ventilation-perfusion lung scanning to determine whether concentrations are increased in pulmonary embolism and their potential use in diagnosis. Lung scans were described as normal (n = 66) or as showing a low (n = 292), indeterminate (n = 58), or high probability (n = 79) of pulmonary embolism. There was a difference between the mean levels of cross linked fibrin degradation products in each scan category: normal scans, 142 ng/ml; low probability scans, 295 ng/ml; indeterminate probability scans, 510 ng/ml; high probability scans, 952 ng/ml (p less than 0.001). Of the patients with high probability scans, 96% had raised concentrations. Explanations for discrepant low results include incorrect scan diagnosis, delay in blood sampling, and anticoagulation. Of the patients with a low or indeterminate probability of pulmonary embolism, 43% had increased concentrations of cross linked fibrin degradation products that could be attributed in most cases to another illness. Owing to the wide range of values in each lung scan diagnostic category, raised concentrations of these fibrin degradation products cannot be used without reference to the patient's clinical state as a discriminatory test for pulmonary embolism. Further evaluation of the significance of normal concentrations in excluding a diagnosis of pulmonary embolism appears to be warranted.

Role of 131I-metaiodobenzylguanidine in the localization of suspected phaeochromocytomas.

Iodine-131-metaiodobenzylguanidine is a recently-developed radiopharmaceutical agent for adrenal medullary scintigraphy. Twenty-one scans with 131I-metaiodobenzylguanidine were performed in 20 adults with suspected phaeochromocytomas over a four-year period. All patients previously had undergone computed tomographic scans of the abdomen and pelvis. The computed-tomographic scans were abnormal in 14 patients (16 tumours), eight (nine tumours) of whose 131I-metaiodobenzylguanidine scans gave positive results. Both types of scan gave negative results in the remaining six patients. Among 12 patients who underwent surgery or postmortem examination, the 131I-metaiodobenzylguanidine scan correctly showed eight phaeochromocytomas; six tumours that were found on computed-tomographic scans but not on 131I-metaiodobenzylguanidine scans proved not to be phaeochromocytoma. The 131I-metaiodobenzylguanidine scan probably gave a true-positive result in an additional case (surgical confirmation was not available). None of the remaining seven patients in whom the 131I-metaiodobenzylguanidine scan gave negative results has been shown to harbour a phaeochromocytoma on extended follow-up (2.5 to four years). Iodine-131-metaiodobenzylguanidine is a highly sensitive and specific agent for the localization of phaeochromocytomas. In patients with suspected phaeochromocytomas and abnormal computed-tomographic findings, 131I-metaiodobenzylguanidine permits a non-invasive, functional evaluation of the morphological abnormalities to be made. The importance of making a biochemical diagnosis of a phaeochromocytoma before attempting localization studies is emphasized.

Localization and treatment of familial malignant nonfunctional paraganglioma with iodine-131 MIBG: report of two cases.

Two cases of familial, malignant, nonfunctional paraganglioma are reported. Uptake of iodine-131 metaiodobenzylguanidine ([131I]MIBG) by the tumors and metastases was demonstrated. In the first case, with multicentric and locally invasive disease, [131I]MIBG correctly localized a right carotid body paraganglioma which had been missed arteriographically. In the second case, with widespread, symptomatic metastatic disease, a therapeutic dose of [131I]MIBG produced palliation of bone pain after the failure of radio- and chemotherapy. Uptake of [131I]MIBG by paragangliomas does not correlate with catecholamine secretory activity. Iodine-131 MIBG should be considered as a therapeutic option in unresectable, malignant paragangliomas which take up this radiopharmaceutical.

Prostaglandin 15-hydroxydehydrogenase activity during pregnancy in rabbits and rats.

Prostaglandin 15-hydroxydehydrogenase (PGDH) activity in the rabbit lung increased strikingly during pregnancy. This change did not occur in the kidney, or spleen. In the corresponding organs from the rat, PGDH activity was essentially the same in pregnant and non-pregnant animals. These results are discussed in relation to the hypothesis that the increased PGDH activity in the pregnant rabbit lung is secondary to an elevated concentration of prostaglandins in the venous blood.