Is jejunal biopsy really necessary in cow's milk protein intolerance?

Thirty-nine infants suspected of having cow's milk protein intolerance (C.M.P.I.) were investigated, and jejunal biopsies were performed before and after challenge with cow's milk. Thirty patients had significant jejunal mucosal damage after milk challenge, but symptoms of diarrhoea and vomiting developed in only twenty-two. The patients with symptoms were subsequently managed on a diet free from cow's milk until tolerance developed. However, the eight infants without symptoms (but with jejunal mucosal damage) made satisfactory clinical progress, with adequate weight-gain, on a diet of cow's milk. Repeat jejunal biopsy specimens from two of these patients showed that there had been a definite improvement since the immediate post-challenge biopsy specimens were taken. Most patients with C.M.P.I. who need to be treated with a diet from which cow's milk has been eliminated may be detected by clinical means alone, and the remainder may continue on a cow's milk diet unless or until symptoms develop. There seems to be no clinical justification for routine jejunal biopsy in infants in whom C.M.P.I. is suspected.