Study Procedures Renal protocol During this protocol a combined inulin/para-aminohippurate (PAH)-clearance technique will be performed to examine the glomerular filtration rate (GFR, ml/min) and effective renal plasma flow (ERPF, ml/min) respectively. In order to examine tubular function, sodium, potassium, chloride, calcium, magnesium, phosphate, urea and glucose will be measured in urine (mmol). In addition, urine osmolality will be determined. Moreover, biomarkers of renal damage (urinary albumin excretion (UAE), Neutrophil gelatinase-associated lipocalin (NGAL) and Kidney Injury Molecule-1 (KIM-1) will be measured in urine