Serum tryptase levels and markers of renal dysfunction in a population with chronic kidney disease.

BACKGROUND

Mast cells (MCs) might play a pathogenetic role in renal fibrosis. Tryptase is a marker for activated MCs. Little is known about tryptase levels in the chronic renal disease population.

METHODS

We examined serum MC tryptase concentrations in relation to specific laboratory abnormalities in 153 outpatients with chronic kidney disease (CKD) and in 35 hemodialysis (HD) patients.

RESULTS

Here we found that tryptase mean values were higher in men than in women (12.4 +/- 7.6 microg/L vs. 10.2 +/- 8.4 microg/L; p<0.05). Tryptase levels were increased in CKD stages 4 and 5 and in HD patients, versus CKD stages 1 and 2: 12.7 +/- 7.3 microg/L, 13.8 +/- 7.8 microg/L, 15 +/- 8.9 microg/L vs. 6.7 +/- 5.1 microg/L (p<0.01). In univariate analysis, in the conservative treatment CKD population, tryptase was positively correlated with urea, creatinine, potassium, uric acid, phosphorus, parathyroid hormone, homocysteine, fibrinogen and proteinuria (p<0.01); tryptase was negatively correlated with calcium, albumin, creatinine clearance, estimated glomerular filtration rate (by abbreviated MDRD equation) and urine creatinine (p<0.01). In HD patients, the only significative correlation found was with systolic blood pressure and diastolic blood pressure (p<0.01). No significant correlations were found between tryptase and other parameters such as albumin, glucose, hemoglobin, leukocytes, immunoglobulins or C-reactive protein. Multiple regression analysis showed estimated glomerular filtration rate and proteinuria to be independent determinants of tryptase.

CONCLUSIONS

This is the first study to determine that tryptase levels increase with higher degrees of kidney dysfunction. The association with markers of diminished renal function suggests impaired metabolism or a negative effect of inflammation on glomerular filtration rate. Further studies are required to ascertain the clinical implications of these findings.