Gastric emptying in patients with collagen diseases using the acetaminophen method

The rate of gastric emptying in patients with collagen diseases and normal subjects was studies using the acetaminophen method. As an indicator of gastric emptying rate, the plasma acetaminophen concentration was measured by fluorescence polarization immunoassay at 45 minutes after ingestion of a high calory pasty test meal (200 ml) with 1.5gram ofacetaminophen. In 8 normal subjects, the plasma concentration was 9.2±0.5μg/ml (Mean±SE). In 15 patients with systemic lupus erythematosus (SLE), 9 patients with progressive systemic sclerosis (PSS) and 4 patients with mixed connective tissue disease (MCTD), the concentration were 10.6±1.2μg/ml, 6.6±1.1μg/ml and 6.6±1.6μg/ml, respectively. 4 of 15 patients with SLE, 5 of 9 patients with PSS and 2 of 4 patients with MCTD showed reduced rate of gastric emptying. The acetaminophen method is considered to be new, simple, safe, and highly reproducible. It is therefore useful for gastric emptying rate in patients with collagen diseases.