Medical Pathology: Kidney (Renal) Disease

Renal System and Diseases Overview

• The urinary system includes kidneys, ureters, urinary bladder, and urethra, with kidneys filtering blood and producing urine.
• Normal urine production ranges from 750 to 2000 mL per day, with clear, amber-colored fluid comprising 95% water and 5% dissolved solids.
• Urinalysis involves visual and microscopic analysis, testing for elements like leukocytes, specific gravity, glucose, protein, and pH.
• Renal function tests include glomerular filtration rate (GFR), inulin as the gold standard, and creatinine clearance rate for estimating GFR.
• Blood urea nitrogen (BUN) levels, creatinine levels, and GFR are used to diagnose kidney disorders, with specific ranges indicating normal kidney function or dysfunction.
• Abnormal blood tests like azotemia and uremia can indicate renal dysfunction, with associated clinical signs and symptoms like hypertension, anemia, edema, and oliguria.
• Renal imaging techniques include ultrasounds, X-rays, CT/MRI scans, and are used to diagnose conditions such as polycystic kidney disease (PKD) and kidney stones.
• In 2021, kidney disease was among the top 10 leading causes of death in the US, following heart disease, cancer, and COVID-19.
• Renal diseases are categorized as nephritic syndromes, nephrotic syndromes, and miscellaneous diseases, with nephrotic syndromes characterized by massive proteinuria and edema.
• Diabetic nephropathy and minimal change disease are common nephrotic diseases, with risk factors and specific treatments outlined for each.
• Diabetic nephropathy is the most common cause of renal disease, with endothelial glycation leading to basement membrane damage, and treatment involving glycemic, blood pressure, and lipid control, as well as dialysis and/or transplant.
• Minimal change disease is the most common cause of nephrotic syndrome in children, with idiopathic and secondary causes, and treatment typically involving steroids, achieving total recovery in 95% of cases.