Chapter 33: Disorders of Renal Function

Urinary tract infections represent the most common renal system infections, typically caused by uropathogenic bacteria such as Escherichia coli that ascend from the lower urinary tract. These infections manifest through characteristic symptoms including urinary urgency, frequency, dysuria, and pyuria visible on urinalysis. Nephrolithiasis, or kidney stone formation, presents as an acutely painful structural disorder in which mineral crystals accumulate within the renal collecting system, producing the classic clinical presentation of flank pain radiating toward the inguinal region alongside hematuria. The chapter emphasizes primary glomerular diseases and glomerulonephritis patterns, including focal segmental glomerulosclerosis with its distinctive histological appearance of sclerotic lesions within some glomeruli, immunoglobulin A nephropathy as the most prevalent primary glomerulonephritis worldwide, and secondary glomerular injury associated with systemic lupus erythematosus. Lupus nephritis exemplifies how systemic autoimmune disease produces kidney damage through immune complex deposition and complement activation. The chapter addresses renal malignancies across the lifespan, including Wilms tumor as the predominant pediatric renal neoplasm with genetic associations including WT1 gene mutations and syndromic presentations, and renal cell carcinoma as the most common adult kidney cancer with discussion of histological subtypes, risk factors including smoking and hypertension, and prognostic staging systems. Understanding these diverse pathological processes requires recognition of disease mechanisms, clinical presentation patterns, diagnostic approaches including imaging and laboratory findings, and therapeutic interventions appropriate to each condition category. The integrated approach enables clinicians and students to systematically evaluate patients with suspected renal pathology and implement evidence-based management strategies.