Relationship between the dexamethasone suppression test and the L-tryptophan/competing amino acids ratio in depression.
Levels of L-tryptophan (L-TRP), of the competing amino acids (CAA) valine and leucine, and of postdexamethasone cortisol taken at 8 a.m., 4 p.m., and 11 p.m. were determined in serum samples from 140 depressive patients. The relationships between postdexamethasone cortisol values, the CAA, and the L-TRP/CAA ratio were assessed using Pearson and Spearman correlation coefficients and multiple regression. There was a significant correlation between postdexamethasone cortisol and both L-TRP and the L-TRP/CAA ratio. The highest correlation coefficients were obtained for the 8 a.m. cortisol values. Nonsuppressors, in comparison with suppressors, showed a significantly lower L-TRP value and L-TRP/CAA ratio.
D000328:Adult; D000367:Age Factors; D000368:Aged; D001835:Body Weight; D003866:Depressive Disorder / Q000097:blood / Q000175:diagnosis*; D003907:Dexamethasone / Q000097:blood; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007930:Leucine / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D014364:Tryptophan / Q000037:antagonists & inhibitors / Q000097:blood*; D014633:Valine / Q000097:blood*
D003907:Dexamethasone; D014364:Tryptophan; D007930:Leucine; D014633:Valine; D006854:Hydrocortisone