Chapter 45: Kidney and Bladder Disorders

Acute kidney injury represents a sudden decline in renal function classified by etiology into prerenal causes involving decreased perfusion, intrarenal injury such as acute tubular necrosis from direct nephron damage, and postrenal obstruction from structural blockages. Diagnostic evaluation relies on laboratory markers including fractional excretion of sodium to differentiate between prerenal and intrarenal causes, with urinalysis revealing characteristic findings like muddy-brown casts in tubular necrosis. The condition progresses through initiating, oliguric, diuretic, and recovery stages, with management tailored to the underlying cause and potentially requiring dialysis for severe complications. Chronic kidney disease involves progressive nephron loss driven primarily by diabetes mellitus and hypertension, with staging based on glomerular filtration rate from stage one with normal filtration but evidence of damage through stage five end-stage renal disease. Diabetic nephropathy causes glomerular hypertension leading to mesangial expansion and glomerulosclerosis, while hypertensive nephrosclerosis involves vascular thickening and narrowing. Clinical manifestations typically emerge when kidney function declines to ten to fifteen percent of normal, presenting with uremia characterized by fatigue, pruritus, and neurological changes. Management emphasizes blood pressure control with renoprotective agents, dietary modifications restricting sodium, protein, phosphorus, and potassium, and treatment of complications including anemia with erythropoietin and renal bone disease with activated vitamin D. Renal cell carcinomas originating in the cortex account for the majority of malignant kidney tumors and often remain asymptomatic until advanced stages when they present with flank pain, hematuria, and palpable masses. Bladder tumors predominantly consist of transitional cell carcinomas with painless hematuria as the classic presenting symptom, strongly associated with cigarette smoking as a risk factor. Treatment approaches vary by disease stage and invasiveness, ranging from endoscopic resection with intravesical immunotherapy for superficial lesions to radical surgical resection combined with chemotherapy and radiation for invasive disease. The chapter emphasizes interprofessional collaboration among primary care providers, nephrologists, urologists, and nutritionists alongside comprehensive patient education regarding nephrotoxic substance avoidance, medication adherence, and dietary compliance for optimal outcomes across the spectrum of renal and urinary tract pathology.