Table 1.

Study Outcomes

Primary Outcome	Change in renal function by assessing eGFR (CKD-EPI) within 2 years
Important Secondary Outcomes	Changes in serum bicarbonate levels, pH, sodium, potassium, and proteinuria measured as protein/creatinine or albumin/creatinine ratio in spot urine
Safety Outcome	Twenty-four-hour ambulatory blood pressure monitoring will be performed at the beginning of the study and after 1 and 2 years
Other Outcomes of Interest	• Changes in measurement of specific acid base transport proteins by urinary exosome collection • Changes in urinary ammonium excretion, inflammatory markers such as complement factors, and hormones involved in tubulo-interstitial nephritis/fibrosis such as endothelin and aldosterone • Histopathological grade of tubulo-interstitial fibrosis according to BANFF classification in kidney biopsies (where available) will be analyzed in both arms • Systemic calcification propensity in blood will be determined by the T50-Test (A test measuring the transformation time (T50) of primary to secondary calciprotein particles, where a long delay of T50 indicates a high residual capacity of the patients’ serum to prevent the formation of secondary calciprotein particles and is therefore a sign of an intact endogenous defense against calcification) [34] • Change of bone density and rejection rate