Deficient intestinal absorption of L-tryptophan in progressive myoclonus epilepsy without Lafora bodies

L-Tryptophan was administered orally to 7 patients with progressive myoclonus epilepsy (PME) without Lafora bodies and 7 controls. Total and free plasma tryptophan wre subsequently measured at intervals. Concentration of free tryptophan was equal in the two groups. Total tryptophan was significantly lower in PME patients and the difference became marked at 120 and 240 min after the oral dose. At the same time urinary excretion of indican rose in PME patients but not in controls but the change was not statistically significant. Urinary 5-HIAA excretion was a little lower in PME patients. The increase of 5-HIAA after administration of L-tryptophan was equal in both groups. Intravenous administration of L-tryptophan produced an equal increase of plasma concentrations in PME patients as in controls, measured at 2-h intervals. These findings suggest incomplete absorption of L-tryptophan through the intestinal tract in PME patients.