Value of clinical features for distinguishing myxedema ascites from other forms of ascites.

The diagnosis of myxedema ascites is often difficult and delayed, from our experience and the reports of other investigators. To address this situation, previous reports on the diagnosis of ascites were pooled in order to distinguish the features of myxedema ascites from other forms of ascites. These features were confined to variables that would be obtained routinely from patients with ascites requiring paracentesis. The data of 26 patients with myxedema ascites, and 61 patients with ascites from another cause were analyzed. Discriminant analysis was used to select the variables that best separated patients into myxedema and non-myxedema groups. The variables selected were if the ascites was straw-colored or with a protein content less than 2.5 g/dl, if the patient was over age 40, and if there was periorbital edema or hepatomegaly. These variables correctly classified 90.8% of patients. However, considering the roughly 1% prevalence of myxedema ascites among patients with ascites, the predictive value of these variables, in combination, is only 8.7%. With this low rate, these variables should probably not be used to screen for myxedema ascites.