GPT and congenital secretory chloride diarrhea 1: In those developing CS-CLD, mean/median levels of liver enzymes were higher, however they remained broadly within normal laboratory limits for transaminases (ALT 44.4 U/l, AST 46.0 U/l), with median GGT levels above the ULN (median 62 vs. 16 U/l, P < 0.001) (Table 2), overall 47% of those with incident CS-CLD had normal liver enzymes (Table 3).