Alt_Renal_Fcn_Class_Notes.pdf

NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Review Overview of Kidney Functions Excretion of metabolic waste products Regulation of water...

NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Review Overview of Kidney Functions Excretion of metabolic waste products Regulation of water and electrolyte balance Regulation of body fluid osmolarity Regulation of acid-base balance Regulation of arterial blood pressure Secretion of hormones Gluconeogenesis 1  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Physiological Processes in the Kidney Filtration Diffusion of plasma molecules across the glomerular membrane Reabsorption Diffusion or active transport of molecules in the urine filtrate from the renal tubules to the peritubular capillaries Secretion Active transport of plasma molecules to the filtrate in the renal tubules Excretion Any filtered molecule that is not reabsorbed + the secreted molecules are excreted 2  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Clinical Measures of Renal Function Glomerular Filtration Rate (GFR) Average GFR: 125 ml/min (males), 115 ml/min (females) Plasma Creatinine Normally 100% of filtered creatinine is excreted, therefore decreased GFR results in an increase in plasma creatinine levels Creatinine Clearance Creatinine clearance (CrCl) can be calculated based on 24 hr urine collections or estimated using urine & plasma (serum) creatinine levels Estimations of CrCl based on plasma creatinine levels Men: CrCl = [weight (kg) x (140-age)]/[72 x plasma creatinine (mg/dl)] Women: CrCl = 0.85 x calculation for men Plasma Blood-Urea-Nitrogen (BUN) Decreased GFR results in an increase in plasma BUN levels. Tends to fluctuate more with changes in plasma osmolarity (i.e., volume status) than plasma creatinine levels 3  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Acute Glomerulonephritis Acute inflammation of the glomerular membrane Primary Etiology Untreated group A beta-hemolytic streptococcal infection – pharyngeal, skin More commonly occurs in children Progression to glomerulonephritis generally occurs 1-2 weeks following pharyngeal infection and 2-4 weeks following skin infection Pathophysiology Overview: Antibodies (IgG) produced against the strep organism cross-react with the glomerular endothelial cells (occurs in 5-10% of cases) Circulating immune complexes (IgG + bacteria) deposit in glomerulus and/or Antibodies directly target glomerular endothelial cells 4  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Activation of inflammatory response Activation of complement system and recruitment of neutrophils and macrophages Inflammatory mediators cause increased capillary permeability in glomerulus Pathophysiological consequences Loss of negative charge of basement membrane Release of growth factors leads to diffuse endothelial and mesangial cell proliferation; thickened filtration membrane leads to decreased GFR Eventually see scar tissue formation at the glomerular membrane 5  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Clinical Consequences and Urinalysis Findings Occur 10-15 days after initial infection Proteinuria (can lead to nephrotic syndrome) Eventually oliguria Acute hematuria Presence of red blood cell casts (matrix of protein and RBCs) Other Possible Causes of Glomerular Injury Drugs or toxins Vascular disorders Systemic diseases (e.g., diabetes mellitus, systemic lupus erythematosus) Non-strep bacterial, viral or even fungal infection 6  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes FYI - Other Types of Glomerulonephritis (Good Patho Blog Topics!) Minimal change disease: inflammation of glomerulus leading to proteinuria/nephrotic syndrome IgA nephropathy (Berger disease) (p. 1382, 6th Ed.): deposition of IgA at the glomerular membrane leads to glomerulonephritis Crescentic (rapidly progressive) glomerulonephritis: causes rapid renal failure. Goodpasture syndrome (anti-glomerular membrane disease): a type of crescentic glomerulonephritis that results in antibody formation against the glomerular membrane & pulmonary capillaries Chronic glomerulonephritis: progressive changes lead to chronic renal failure 7  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Acute Kidney Injury Abrupt reduction in renal function usually associated with oliguria Prerenal Acute Kidney Injury (AKI) AKI caused by impaired renal blood flow Causes Obstructed renal artery Hypotension Pathophysiology Ischemia leads to renal hypoxia and acute tubular necrosis Decrease in filtration pressure 8  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Intrarenal Acute Kidney Injury AKI caused by damage to renal parenchyma Causes Acute glomerulonephritis Prerenal acute renal failure Malignant hypertension Drugs (IV contrast, NSAIDS, ACE inhibitors, some antibiotics, and others) Infection or autoimmunity Pathophysiology Acute tubular necrosis from ischemia or other direct injury to glomerulus and surrounding structures 9  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Postrenal Acute Kidney Injury Urinary tract obstruction that affects kidneys bilaterally Causes Kidney stones (calculi) Bladder outlet obstruction Pathophysiology Obstruction causes increased pressures in glomerular capsule and decreased GFR 10  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Clinical Consequences and Manifestations of Acute Renal Failure Oliguria Mechanisms (see Fig. 38-11, p. 1362, 7th Ed.) Alterations in renal blood flow Renal tubular obstruction Renal tubular back leak Elevated plasma creatinine Elevated blood urea nitrogen (BUN) Elevated plasma potassium (hyperkalemia) Metabolic acidosis Fluid overload & hypertension 11  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Chronic Kidney Disease Progressive (and irreversible) loss of renal function Common Etiologies Diabetes mellitus Hypertension Pathophysiology & Clinical Manifestations of Stages Stage 1 CKD (GFR > 90 mL/min) Stage 2 CKD (GFR 60-89 mL/min) Stage 3 CKD (GFR 30-59 mL/min) Stage 4 CKD (GFR 15-29 mL/min) Stage 5 CKD (GFR < 15 mL/min) 12  NURS 7053 – Advanced Pathophysiology for DNP Students Alterations of Renal Function - Class Notes Clinical Manifestations of Chronic Kidney Disease Hypertension Anemia Hyperparathyroidism Hyperphosphatemia Hyperkalemia Metabolic acidosis Sodium and Fluid Imabalance Proteinuria Uremia 13