How is the urinalysis helpful in patients with kidney disease? -- How should changes in plasma creatinine be interpreted? -- What is a fractional excretion (and how does measuring it help in clinical practice)? -- What is the urine albumin to creatinine ratio? (or is it protein to creatinine ratio?) -- What is the meaning of the urine to plasma creatinine ratio? -- Is it helpful to diagnose a triple acid-base disturbance? (or is it just a mental exercise?) -- Why are disorders of sodium concentration so difficult? -- What is free water clearance and how useful is it? -- How does one interpret the urine anion gap and urine osmolal gap? -- Is it 'acute renal failure' or 'acute kidney injury'? -- What exactly is dialysis and when is it needed? -- When does metabolic acidosis require treatment with bicarbonate? -- Is there any advantage to colloids vs. crystalloids for volume repletion? -- Is computed tomography (CT) with contrast or magnetic resonance imaging (MRI) with contrast preferred in patients with chronic kidney disease? -- Is there a risk to rapidly lowering the plasma potassium in patients with hyperkalemia? -- Should calcium-based phosphate binders be used in patients with chronic kidney disease? -- Which renal cysts require follow-up evaluation? -- Are renin angiotensin aldosterone system blockers friends or foes of the kidneys? -- Does a patient with a mild decrease in estimated glomerular filtration rate (eGFR) really have a disease? -- Why are kidney stones a nephrologic as well as a urologic disease?