TAMM-HORSFALL PROTEIN IN URINE AFTER UNINEPHRECTOMY TRANSPLANTATION IN KIDNEY DONORS AND THEIR RECIPIENTS/

Tamm-Horsfall protein (THP) is a large glycoprotein with unknown physi ological function synthesized in the thick ascending limb of the loop of Henle. Urinary THP has recently been suggested as being suitable fo r monitoring the functional state of transplanted kidneys. In the pres ent study, the urinary excretion of THP after uninephrectomy and trans plantation among relatives was determined in order to study the influe nce of the acute reduction in renal mass on the excretion of this pept ide. Glomerular filtration rate (GFR), estimated by the plasma clearan ce of Cr-51-EDTA, and the excretion rate of THP were measured 2 days b efore nephrectomy and 5, 12, 26 and 54 days after nephrectomy/transpla ntation in 22 healthy Living kidney donors and in 16 of their recipien ts. In the donors, THP excretion rate of the kidney to remain in the d onor was 22.3 mu g/min before and 33.7 mu g/min at 5 days after uninep hrectomy (p < 0.01) and remained increased by around 40% throughout th e study period. GFR of the remaining kidney rose from 47 ml/min before to 61 ml/min at 5 days after uninephrectomy (p < 0.001). The THP excr etion rate/GFR ratio remained unchanged in the donors. In the kidney t o be transplanted, THP excretion rate was unchanged before and after t ransplantation. There was no significant increase in GFR in the recipi ents, which was significantly lower than GFR of the donors all the tim e. In matched pairs of kidney donors and recipients, the THP excretion rate/GFR ratio tended to be lower in the recipients but the differenc e was not significant. The correlation between excretion rate of THP a nd GFR was significant (r = 0.66; p < 0.01). To conclude, uninephrecto my in healthy man was associated with a marked increase of around 40% in the excretion of THP from the kidney that remained in the donor. In the kidney that was transplanted, the THP excretion rate was unchange d. The THP excretion rate was correlated with GFR. The mechanism under lying this association is unknown as THP does not undergo glomerular f iltration.