Safety of the oral methionine load test: effects on the clinical performance and laboratory tests

Hyperhomocysteinemia is a prothrombotic risk factor. Homocysteine is evaluated during fasting and after an oral methionine load (OML).

To determine the safety of the OML test according to the general performance status and clinical laboratory tests. We studied healthy nonsmoking volunteers and patients with several thrombotic conditions. Before and after receiving an OML, blood samples were obtained to perform several laboratory tests. We also evaluated acute and subacute adverse effects and 30-day associated morbidity and mortality. Of 353 individuals, three were eliminated because they did not tolerate the OML. We studied 175 healthy individuals and 175 patients without age differences. After OML, mild to moderate clinical abnormalities were recorded in 78 subjects (22.1%): nausea (n = 69; 88.5%), dizziness (n = 13; 16.7%) and decreased or increased blood pressure (n = 8; 10.2%). Nausea always disappeared after breakfast in affected individuals. Prevalence of complications was similar in patients and controls. No patient required hospitalization and there was no mortality during the 30-day study period. In conclusion, OML test had no significant undesirable effects on the clinical status or the general laboratory tests of patients and healthy controls. Some mild and moderate symptoms associated with OML tests were observed, and OML test did not negatively affect general laboratory tests. OML test is a safe diagnostic procedure in patients with previous thrombotic events (and with the consequent associated risk factors such as diabetes mellitus or dyslipidemia) and in healthy subjects.