MORPHOLOGICAL CORRELATES OF URINARY ENZYME LOSS AFTER EXTRACORPOREAL LITHOTRIPSY

Urinary loss of the tubular marker enzyme N-acetyl-beta-D-glucosaminid ase (NAG) immediately following extracorporeal lithotripsy suggests co rresponding morphological changes in the kidney. To date, the morpholo gical correlate of the enzymuria remains unclear. In this animal study with Wistar rats acute morphological changes in the tubulus cells ben eath isolated tubulus necrosis were demonstrated. The mechanically ind uced lesions of the cell organelles included fragmentation of the lyso somes and severe alterations of the cell membrane. The tubulus damage was quantified. With the help of histochemical NAG staining and electr on microscopic observations, a significant correlation between number and intensity of shock waves and tubular damage was found. The intrace llular lesions described here are at least part of the morphological b asis of shock-wave-induced enzymuria. The results show that enzymatic changes in urine reflect visible renal damage.