Assessment of one-carbon status. Homocystinuria.
Patient/subject: Prandial status affects concentration, which increases after a protein rich meal.
Matrix: Serum or EDTA plasma.
Volume: Minimum volume is 50 µL, but 200 µL is optimal and allows reanalysis.
Preparation and stability: Methionine is converted to methionine sulfoxide, even at low temperature and in samples frozen at -20 °C.
Reported values: 18-50 µmol/L.
Intraclass correlation coefficient (ICC): 0.33.
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