Μελέτη της σωληναριακής μεταφοράς του ουρικού οξέος στην πολυκυστική νόσο των ενηλίκων με τη χρήση των δοκιμασιών πυραζιναμίδης και προβενεκίδης

The human kidney is responsible for 2/3 to 3/4 of the excretion of the daily load of uric acid, the final product of the purine metabolism. In spite of the fact that uric acid is almost totally filtered in the glomeruli, only 10 % of the filtered quantity is excreted in the urine, because of extensive reabsorption of urate. Many factors affect the tubular transport of urate, some by increasing the tubular transport (extracellular volume increment, sodium load, hyperglycemia, ADH, contrast media, drugs e.t.c.), and others by decreasing it (organic acids, angiotensin II, norepinephrine, PTH, drugs, e.t.c.). In chronic renal failure (CRF) irrelevant of primary kidney disease, recent studies have shown that the quantity of the urate excreted per nephron is increased, mainly by a supression of postsecretory reabsorption, and also by supression of presecretory reabsorption, which is becomes more obvious in the final stages of the disease. The renal handling of urate was studied by probenecid and pyrazinamide tests, in 58 patients with adult dominant polycystic kidney disease (ADPKD), 25 with normal renal function and the rest with various degrees of chronic renal failure. The above 58 patients were compared to 21 healthy persons and 42 patients suffering from glomerulonephritis (G/N) (among them 11 with normal renal function and the rest with chronic renal failure), who served as a control group. The 21 persons with normal renal function comprised group M of controls, while the patients with ADPKD as well as those with G/N were separated into 5 groups. All groups were comparative in age, sex and creatinine clearance (except Group E where creatinine clearance was significantly higher in G/N patients). Group A with a creatinine clearance higher than 80 ml/min. Group Β with a creatinine clearance ranging from 40 to 80 ml/min. Group C with a creatinine clearance ranging from 20 to 40 ml/min. Group D with a creatinine clearance ranging from 10 to 20 ml/min and Group E with a creatinine clearance less than 10 ml/min. Upon the comparison of the results between the groups with normal renal function, the plasma urate levels did not show any significant difference between the ADPKD group and the controls (group M). However plasma urate levels were found to be significantly higher in G/N patients comparing to controls (p<0.02). Renal clearance of urate was higher in ADPKD and lower in G/N, but signifficant differences were found only between the control group and G/N (p<0.02) as well as between G/N and ADPKD (p<0.05). The fractional excretion of urate in the ADPKD group with normal renal function was higher in comparison to the other two groups (M, G/N), but statistically significant level was found only between ADPKD and G/N group (p<0.05). This parameter was also found to be significantly higher in controls (Group Μ), comparing to the same group of G/N (p<0.01). Between these three groups no difference was found concerning all the others parameters. The higher excretion of urate in the ADPKD, in relation to the G/N group, is due to the reduction of the presecretory reabsorption of the filtered urate in the former. A possible cause of this difference could be the increment of the extracellular volume which was found in patients with ADPKD and normal renal function. The renal clearance of urate in patients with ADPKD and CRF was found to be significantly higher, from that of G/N patients, only between the C groups (p<0.01) The fractional excretion of urate was also higher in all groups of ADPKD patients with CRF, from that of G/N patients, but reaching to statistically significant levels only between groups C and E. The filtered urate, which do not influence the excreted amount of urate, was lower in all groups of the ADPKD patients with CRF, comparing to the similar G/N groups, but a statistically significant difference was found only between the C groups (p<0.02). Similar results were obtained when the amount of the presecretory reabsorptive urate was compared between groups (ADPKD vs G/N C group, p<0.05). No difference was found between the secreted and postsecterory reabsorptive urate. The excreted urate in all groups of the ADPKD patients was found to be higher in comparison to G/N groups, but a statistically significant difference was found only between groups C (p<0.05). From this study we conclude the following: 1. Patients with ADPKD and normal renal function did not show any difference in the plasma urate levels and the tubular handling of urate, comparing to controls (Group M). In contrast patients with G/N and normal renal function showed statistically significant higher plasma urate levels comparing to controls and this is attributed to statistically significant lower urate renal clearance and fractional excretion of urate in the former group. 2. All the groups of ADPKD patients with CRF, showed a higher urate clearance and fractional excretion of urate when compared to the similar groups of the G/N patients. This difference reached a statistically significant level only in group C and it is probably due to the difference in the presecretory reabsorption of urate, which was higher in the G/N patients. 3. In conclusion patients with ADPKD and normal renal function have normal renal handling of urate and their urate plasma levels are within normal range. During the evolution of ADPKD to end stage renal failure these patients showed lower urate plasma levels and higher renal clearance as well as fractional excretion of urate, comparing to G/N patients with the same degree of renal failure.

Grantor dc:publisher

Aristotle University Of Thessaloniki (AUTH)

Year dc:date

1991

Author dc:creator

• Mavromatidis, Konstantinos

• Ιατρική και Επιστήμες Υγείας
• Κλινική Ιατρική
• Medical and Health Sciences
• Clinical Medicine

Language dc:language

gre

Identifier

10.12681/eadd/1605

OAI identifier oai:identifier

oai:10442/1605