Ansari, Kiana (2012) Renal acid handling after donor nephrectomy. thesis, Medicine.
Full text available on request.Abstract
Background: Live kidney donation is considered to be safe, but the effect of unilateral nephrectomy on renal acid handling has not yet been studied. Since urinary pH is involved in the risk of developing nephrolithiasis and an acidic urine possibly has an adverse effect on renal function, further insight in this matter is needed. Unilateral nephrectomy results in a compensatory hypertrophy that is incomplete. The most important part of acid excretion by the kidneys is the excretion of ammonium. Since there is a limit to the amount of ammonium that renal tubular epithelial cells can produce, capacity for ammonium generation is conceivably lower after unilateral nephrectomy. This could possibly result in recruitment of other buffering systems such as calcium hydroxide, which raises the hypothesis that there is an increase in excretion of calcium and titratable acid after donation. We compared 127 donor patients prior to and after donation to determine what the effect of unilateral nephrectomy is on urinary pH, systemic pH and urinary excretion of calcium, ammonium and titratable acid. Methods: Donors were asked to participate in our study twice every week and the recruitment had started in 2008 in the UMCG. 24-hour urine samples and blood was collected. Aliquots of these urine samples were stored at -80 degrees centigrade. Plasma and urinary concentrations of electrolytes were measured using routine clinical laboratory methods. Urinary pH and titratable acid were measured by an automatic titrator. Renal function was assessed by constant infusion of low-dose radio-labeled tracers 125I-iothalamate and 131I-hippurate. Results: Urinary pH was significantly lower after donation (mean ± SD 6.28 ± 0.43 pre-donation versus 6.07 ± 0.76 post-donation, p < 0.001), whereas systemic pH did not significantly change (mean ± SD 7.38 ± 0.03 pre-donation versus 7.37 ± 0.03 post-donation, p = 0.338). There was no significant change in urinary ammonium and titratable acid excretion, although the ratio of ammonium/titratable acid was lower after donation (median [interquartile range] 0.84 [0.56-1.38] pre-donation versus 0.79 [0.61-0.97] post-donation, p = 0.036). Calcium excretion was significantly lower after donation (median [interquartile range] 5.23 [3.51-6.83] pre-donation versus 2.93 [1.90-4.09] post-donation, p < 0.0001). Conclusion: The lower urinary pH suggests some degree of impairment in renal acid handling, but the systemic pH remains the same after donation. The results suggest that capacity for ammonium generation remains about the same, although there is a higher contribution of titratable acid to the acid excretion after donation. The lower urinary calcium excretion was unexpected and may be a consequence of reduced calcium uptake in the intestines.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Bakker, dr. S.L.J. Department of Internal Medicine |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:48 |
| Last Modified: | 25 Jun 2020 10:48 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/929 |
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