Overflow proteinuria

Urinary or Gastrointestinai Loss. Because of its small size, AAT diffuses into the glomerular urine and into the gastrointestinal tract however, AAT is not seen in the excreted urine unless there is damage to the proximal tubular cells or marked overflow proteinuria, as in the nephrotic syndrome. In the latter case, the serum level of AAT may be depressed, especially in the absence of an acute phase reaction. AAT is normally present in the excreted stool, mostly compiexed to pancreatic trypsin and elastase. In protein-losing enteropathies, the loss may be greatly increased. 

Overflow proteinuria. This occurs as a result of an accumulation of particular proteins in the blood, e.g. Bence-Jones protein in myeloma or myoglobin in crush syndrome (qv). 

The three main types of proteinuria are glomerular, overflow, and tubular proteinuria. 

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