EXCESS GLYCOSAMINOGLYCAN EXCRETION IN INFANCY AND CHILDHOOD

Summary Experience with a simple cetylpyridinium chloride screening test for detection of excess urinary glycosaminoglycans (GAG) is described. The causes of false positive results are listed. A simplified approach avoiding time‐consuming laboratory procedures such as column chromatography has been used to study glycos‐aminoglycan excretion in children giving a positive screening test. GAG have been isolated in crude form using cetylpyridinium chloride and analysed for hexosamine content and resistance to hyaluronidase digestion without further separation and purification. A simple electrophoretic separation has been used as supportive evidence for any abnormality detected. Use of this simplified approach has been of value in the diagnosis of mucopolysacchari‐doses. Children with false positive screening test can readily be shown to be normal excre‐tors. A few anomalous results have been found in mentally retarded children and patients with other bone dysplasias. More important, the methods used highlight the problem of detecting abnormal glycos‐aminoglycan excretion in the first year of life. Our results in this age group suggest that the full picture of abnormal excretion may be a late development in the mucopolysaccharidoses and where there is a high index of suspicion that an infant may have one of these disorders, a full, detailed analysis is desirable. The simple methods used here are of value in this respect since they are less time‐consuming than other methods and are easily undertaken by routine hospital clinical chemistry departments without specialized research facilities and staff.