D.R. Barnett

522 QUANTITATIVE FECAL ALPHA-1-ANTITRYPSIN TO MEASURE GASTROINTESTINAL PROTEIN LOSS

Excessive protein loss through the gastrointestinal tract is difficult to diagnose and quantitate because of the nonavailability of radiolabelled proteins and the disadvantages of their administration to children. Alpha-l-antitrypsin (α1AT) is an endogenous protein which is resistant to proteolytic digestion in the intestine, not found in the diet and as suggested by others should reflect plasma protein loss into the GI tract. We investigated its usefulness by measuring the fecal α1AT concentration in 24 patients with no malabsorption, 12 patients with cystic fibrosis (high fecal nitrogen), 10 patients with fat malabsorption only and 3 patients with protein-losing enteropathies. Stool aliquots were taken from 48-72 hour homogenized stool collections which had been evaluated for fecal fat. Five lambda samples were directly applied to and quantitated by radial immunodiffusion plates specific for anti-human αlAT (Boehringer-Mannheim). “Normal” daily αlAT loss expressed in mg/kg body wt/day was 1.70 ± 1.32 with similar values for cystic fibrosis (0.99 ± 0.68, p>0.05) and isolated fat malabsorption (1.51 ± 1.03, p>0.05). The α1AT loss for the 3 patients with protein-losing enteropathies (two with lymphangectasia, one undiagnosed) varied from 4.4-48 mg/kg per day and correlated with clinical criteria for protein loss. Conclusion: Fecal α1AT quantitation may be specific for measuring protein loss into the gastrointestinal tract.

559 POLYAMINE (PA) METABOLISM IN CYSTIC FIBROSIS (CF)

Prior studies have shown that PA levels are elevated in blood components of CF homozygotes. We have studied urinary PA levels and 14C spermidine metabolism in controls and CF patients. The urinary PA levels in 7 CF homozygotes were 2-10 fold higher than in 8 heterozygotes and 6 normals (p<0.0001). No statistically significant differences were found between heterozygotes and controls. The 14C spermidine plasma decay curves in two CF patients with severe clinical disease (NIH Score <50) were not significantly different from normal. However, urinary excertion of the 14C radiolabel by the 2 CF patients was only about 10% as compared to 60-76% excreted by normals after 72 hours. Urine samples were obtained and NIH Clinical Scores were assigned to a group of 12 CF patients. Those with scores <70 (N = 4) demonstrated statistically significant lower levels of putrescine (p <0.05) and significantly higher levels of spermine (p <0.01) than those with scores >70 (N = 8). These data show that although plasma decay curves for 14C spermidine are similar to normals, the urinary excretion pattern suggests sequestration in CF patients with severe clinical disease. Further, polyamine levels are elevated in the urine of CF homozygotes and appear to correlate well with the patients clinical status.Supported by USPHS Grants CA-14783 and CA-17094 from the National Cancer Institute (D.H.R.). R.B. is an ALA Fellow.