Disorders of Renal Function PDF

Disorders of Renal Function  OBJECTIVES By the end of the lecture , the students will be able to : 1. List down the components of the renal system 2. List down the functions of the renal system 3. Explain the process of urine formation 4. Describe the pathophysio...

Disorders of Renal Function  OBJECTIVES By the end of the lecture , the students will be able to : 1. List down the components of the renal system 2. List down the functions of the renal system 3. Explain the process of urine formation 4. Describe the pathophysiology of Disorders of the renal system 2  3 RENAL SYSTEM Components of the renal system: kidneys, ureters, bladder, and urethra. 1.The kidneys - located retroperitoneally in the lumbar area Functions: ⮚ Produce and excrete urine to maintain homeostasis. ⮚ Regulate the volume, electrolyte concentration, and acid-base balance of body fluids. ⮚ Detoxify the blood and eliminate wastes. ⮚ Regulate blood pressure. ⮚ Support red blood cell production (erythropoiesis).  4 RENAL SYSTEM 2.The ureters - tubes that extend from the kidneys to the bladder ⮚ Function: transport urine to the bladder. 3.The bladder- a muscular bag ⮚ Function: serves as reservoir for urine until it leaves the body through the urethra.  5 NEPHRON Nephron is the functional unit of kidney Consists of: Renal Corpuscle, Renal Tubules Renal Corpuscle contains: Bowman’s capsule: Part of collecting system Glomerulus: Afferent arteriole, Efferent arteriole Renal/Nephron Tubules 1. Proximal convoluted tubule 2. Loop of Henle 3. Distal convoluted tubule 4. Collecting tubule  6 FOUR SEGMENTS OF THE RENAL/NEPHRON TUBULE Proximal Convoluted Tubule A highly coiled segment; drains into the Bowman capsule Loop of Henle A thin looped structure Distal Convoluted Tubule A distal coiled portion Collecting Tubule Joins with several tubules to collect the filtrate Functions of the Nephron: 1. Glomerular filtration - Three layers of filtration 2. Reabsorb water, electrolytes, and other substances 3. Secrete other unneeded materials into the tubular filtrate for elimination  7 URINE FORMATION 1. Glomerular Filtration Occurs in renal corpuscle, All solutes in the glomerular capillaries, except for macromolecules like proteins, pass through by passive diffusion. Glomerular filtration rate (GFR) is the volume of glomerular filtrate formed per minute (125ml/min) by the kidneys. 2. Reabsorption Occurs in proximal convoluted tubule and distal convoluted tubule Movement of substances from tubular fluid to blood. 3. Secretion Occurs in distal convoluted tubule Movement of substances from blood to tubular fluid. 4. Concentration Occurs in collecting tubules  8 FACTORS AFFECTING URINE PRODUCTION Two key factors determine volume of urine produced. 1. Glomerular filtration rate (GFR) - Determined by the unique arrangement of blood vessels. 3 factors control this: (1) Autoregulation -Local feedback from muscle tension in afferent arteriole (2) Sympathetic nervous system (3) Renin 2. Hormonal secretion - Hormones help control the volume of urine via fluid & electrolyte balance 1. Aldosterone: From adrenal cortex, Causes H2O & Na+ retention 2. Atrial natriuretic hormone(ANH):From atrial wall of heart, Causes H2O & Na+ loss 3. Antidiuretic hormone: From posterior pituitary, Causes reabsorption of H2O (Na+ goes with it)  Urinary Tract Infections Urinary tract infections (UTIs) are extremely common, it is estimated that 6 million Americans are affected annually. Urine generally provides an excellent medium for growth of microorganisms. Cystitis and urethritis are considered infections of the lower urinary tract, whereas pyelonephritis is an upper tract infection. Most infections are ascending, arising from organisms in the perineal area and traveling along the continuous mucosa in the urinary tract to the bladder and then along the ureters to the kidneys. Occasionally pyelonephritis results from a blood-borne infection. The common causative organism is Escherichia coli, which is one of the resident flora of the intestine (approximately 85%). 9 10  Urinary Tract Infections Etiology Women are anatomically more vulnerable to infection than men because of the shortness and width of the urethra, its proximity to the anus The frequent irritation to the tissues caused by sexual activity, bubble bath, and deodorants. Improper hygiene practices during defecation or menstruation also increased risk. Older men with prostatic hypertrophy and retention of urine frequently develop infection. Congenital abnormalities are a common cause of infection in children, particularly where obstructions to flow or reflux are present Incontinence with incomplete emptying of the bladder, retention of urine in the bladder, and any obstruction to urine flow, which tends to result in growth of organisms Pregnancy, scar tissue, and renal calculi (kidney stones) 11  Pathophysiology Cystitis With cystitis, the bladder wall and urethra are inflamed, red, and swollen, and in some cases, ulcerated. The bladder wall is irritated and hyperreactive and bladder capacity is usually reduced. Signs and symptoms In some cases, the manifestations are very mild and may be unnoticed. Pain is common in the lower abdomen. Dysuria (painful urination), urgency (need to void immediately), frequency (short intervals between voiding), and nocturia (need for urination during sleep period) occur as the inflamed bladder wall is irritated by urine. Systemic signs of infection may be present (fever, malaise, nausea, and leukocytosis). The urine often appears cloudy and has an unusual odor. Urinalysis indicates bacteriuria (more than 100,000 organisms per milliliter of urine), pyuria, and microscopic hematuria 12  Incontinence and Retention Incontinence, or the loss of voluntary control of the bladder, has many causes. Young children must learn voluntary control as the nervous system matures. Enuresis defines involuntary urination by a child after age 4to 5, when bladder control can be expected. Most children have nocturnal enuresis only. Most cases appear to be related to factors such as a developmental delay, sleep pattern, or psychosocial aspects rather than to a physical defect. Types of incontinence: 1) Stress incontinence occurs when increased intra-abdominal pressure forces urine through the sphincter. This can occur with coughing, lifting, or laughing, but occurs more frequently in women after the urogenital diaphragm has become weakened by multiple pregnancies or age. 13  Incontinence and Retention 2) Overflow incontinence results from an incompetent bladder sphincter. In the elderly, a weakened detrusor muscle may prevent complete emptying of the bladder, leading to frequency and incontinence. Spinal cord injuries or brain damage frequently cause a neurogenic bladder, which may be spastic or flaccid, due to interference with central nervous system (CNS) and autonomic nervous system control of the bladder emptying. 3) Retention: is an inability to empty the bladder. It may be accompanied by overflow incontinence. Note that a spinal cord injury at the sacral level blocks the micturition reflex, resulting in retention of urine or failure to void. Retention also may occur after anesthesia, either general or spinal. Inability to control urine flow may be managed by wearing pads or briefs that contain the urine. Catheters prevent kidney damage due to backup of urine, collect urine, and prevent skin breakdown in the incontinent client. 14  15 ACUTE PYELONEPHRITIS Also known as acute infective tubulointerstitial nephritis is A sudden inflammation caused by bacteria that primarily affects the interstitial area and renal pelvis or, less commonly, the renal tubules. More common in females, probably because of: ⮚ A shorter urethra ⮚ The proximity of the urinary meatus to the vagina ⮚ A lack of the antibacterial prostatic secretions produced in males CAUSES Bacterial infection of the kidneys, including normal intestinal and fecal flora that grow readily in urine ⮚ Escherichia coli (E. Coli) is the most common causative organism ⮚ Other causative organisms : Enterococcus faecalis, Klebsiella, Staphylococcus aureus  16 ACUTE PYELONEPHRITIS Pathophysiology: Typically, the infection spreads from the bladder to the ureters, and then to the kidneys, such as in vesicoureteral reflux. Causes : ❖ congenital weakness at the junction of the ureter and bladder ❖ instrumentation, such as catheterization ❖ from a hematogenic infection, such as in septicemia ❖ inability to empty the bladder ❖ urinary obstruction due to tumors. Bacteria refluxed to intrarenal tissues may create colonies of infection within 24 to 48 hours. Recurrent episodes of acute pyelonephritis can eventually result in chronic pyelonephritis.  17 CHRONIC PYELONEPHRITIS Persistent kidney inflammation that can scar the kidneys and may lead to chronic renal failure. Causes: bacterial, metastatic, or urogenous. Most common in patients who are predisposed to recurrent acute pyelonephritis such as those with urinary obstructions or vesicoureteral reflux. Signs/symptoms: childhood history of unexplained fevers or bed- wetting, flank pain, anemia, low urine specific gravity, proteinuria, leukocytes in urine and, especially in late stages, hypertension.  18 GLOMERULONEPHRITIS Bilateral inflammation of the glomeruli, typically following a streptococcal infection Acute glomerulonephritis is most common in boys ages 3 to 7, but it can occur at any age Chronic glomerulonephritis is a slowly progressive disease characterized by inflammation, sclerosis, scarring and, eventually, renal failure  19 GLOMERULONEPHRITIS PATHOPHYSIOLOGY The epithelial layer of the glomerular membrane is disturbed. Results from the entrapment and collection of antigen-antibody complexes in the glomerular capillary membranes Glomerular injury occurs and increase membrane permeability which causes a loss of negative charge across the glomerular membrane as well as enhanced protein filtration. The inflammatory response decreases the GFR, which causes fluid retention and decreased urine output  20 GLOMERULONEPHRITIS Signs/symptoms: Decreased urination or oliguria due to a decreased GFR Smoky or coffee-colored urine due to hematuria Dyspnea and orthopnea due to pulmonary edema secondary to hypervolemia Periorbital edema due to hypervolemia Mild to severe hypertension due to a decreased GFR, sodium or water retention  21 RENAL FAILURE A condition in which the kidneys fail to remove metabolic end products from the blood and regulate the fluid, electrolyte, and pH balance of the extracellular fluids Causes: Renal disease Systemic disease Urologic defects of non-renal origin Types: Acute Renal Failure Abrupt in onset Often is reversible if recognized early and treated appropriately Chronic Renal Failure The result of irreparable damage to the kidneys It develops slowly, usually over the course of a number of years  22 ACUTE RENAL FAILURE Abrupt decrease in renal function Prerenal Causes : Hypovolemia Heart failure and cardiogenic shock Decreased renal perfusion Intrarenal Causes : Prolonged renal ischemia Exposure to nephrotoxic drugs, metals, organic solvents Acute renal disease Postrenal Causes : Bilateral ureteral obstruction Bladder outlet obstruction  23 CHRONIC RENAL FAILURE Slow progressive loss of neurons, Usually irreversible Causes: Hypertension Diabetes Mellitus Polycystic kidney disease Obstructions of the urinary tract Glomerulonephritis Cancers  24 CHRONIC RENAL FAILURE The pathophysiology of prerenal, intrarenal, and postrenal failure differs A. Prerenal failure: Occurs when a condition that decreases blood flow to the kidneys (hypo perfusion). Azotemia (excess nitrogenous waste products in the blood) develops in 40% to 80% of acute renal failure cases. When renal blood flow is interrupted, so is oxygen delivery. The ensuing hypoxemia and ischemia can rapidly and irreversibly damage the kidney tubules. The impaired blood flow results in decreased glomerular filtration rate (GFR) and increased tubular reabsorption of sodium and water. A decrease in the GFR causes electrolyte imbalance and metabolic acidosis.  25 CHRONIC RENAL FAILURE B. Intrarenal failure: results from damage to the filtering structures of the kidneys. Causes are classified as nephrotoxic, inflammatory, or ischemic. When the damage is caused by nephrotoxicity or inflammation, the delicate layer under the epithelium becomes irreparably damaged, typically leading to necrosis and chronic renal failure. Severe or prolonged lack of blood flow caused by ischemia may lead to renal damage (ischemic parenchymal injury) and excess nitrogen in the blood (intrinsic renal azotemia). The ischemic tissue generates toxic oxygen-free radicals, which cause swelling, injury, and necrosis. Postrenal failure: Bilateral obstruction of urine outflow leads to damage of renal parenchyma. The cause may be in the bladder, ureters, or urethra.  26 CHRONIC RENAL FAILURE Phases: The three types of acute renal failure (prerenal, intrarenal, or postrenal) usually pass through three distinct phases: oliguric, diuretic, and recovery. 1. Oliguric phase : ⮚ Necrosis of the tubules can cause sloughing of cells and ischemic edema and a decrease in the GFR. ⮚ Urine output may remain at less than 30 ml/hour or 400 ml/day for a few days to weeks. 2. Diuretic phase: ⮚ Kidneys become unable to conserve sodium and water. ⮚ Increased urine secretion of more than 400 ml/24 hours, may last days or weeks.. 3. Recovery phase: ⮚ If the cause of diuresis is corrected, azotemia gradually disappears, and recovery occurs. ⮚ The recovery phase is a gradual return to normal or near normal renal function over 3 to 12 months.  27 CHRONIC RENAL FAILURE Clinical manifestations Early signs include oliguria , azotemia, electrolyte imbalance and metabolic acidosis GI—anorexia, nausea, vomiting, diarrhea or constipation Central nervous system (CNS)— headache, drowsiness, irritability, confusion, seizures, coma Cutaneous—dryness, pruritus Cardiovascular—early in the disease, hypotension; later, hypertension, arrhythmias, fluid overload, heart failure, systemic edema, anemia, altered clotting mechanisms Respiratory—pulmonary edema,.  28 NEPHROTIC SYNDROME Results from a defect in the permeability of glomerular vessels. About 75% of all cases result from primary glomerulonephritis. Marked proteinuria, hypoalbuminemia, hyperlipidemia, and edema characterize nephrotic syndrome. CAUSES Allergic reactions Circulatory diseases, such as heart failure Sickle cell anemia Collagen-vascular disorders, such as systemic lupus erythematosus Hereditary nephritis Infections, such as tuberculosis  29 NEPHROTIC SYNDROME The pathophysiology The injured glomerular filtration membrane allows the loss of plasma proteins, especially albumin and immunoglobulin. In addition, metabolic, biochemical, or physiochemical disturbances in the glomerular basement membrane result in the loss of negative charge as well as increased permeability to protein. Hypoalbuminemia stimulates the liver to synthesize lipoprotein, with consequent hyperlipidemia. CLINICAL MANIFESTATIONS ⮚ Periorbital edema due to fluid overload ⮚ Mild to severe dependent edema of the ankles or sacrum ⮚ Orthostatic hypotension due to fluid imbalance ⮚ Ascites due to fluid imbalance & Respiratory difficulty due to pleural effusion  30 RENAL CALCULI Renal calculi, or stones (nephrolithiasis), can form anywhere in the urinary tract, although they most commonly develop on the renal pelves or calyces. They may vary in size and may be solitary or multiple. CAUSES Changes In Urine pH Dehydration Dietary Factors Gout Immobilization Obstruction To Urine Flow Leading To Stasis In The Urinary Tract Renal disease  31 RENAL CALCULI Pathophysiology: Calculi form when substances that are normally dissolved in urine, such as calcium oxalate and calcium phosphate, precipitate. Dehydration may lead to renal calculi as calculus-forming substances concentrate in urine. Calculi may either enter the ureter or remain in the renal pelvis, where they damage or destroy renal parenchyma and may cause pressure necrosis. In ureters, calculi cause obstruction with resulting hydronephrosis and tend to recur. CLINICAL FINDINGS Mild to severe flank pain resulting from obstruction Nausea with or without vomiting Fever and chills from infection  Hydronephrosis This occurs as a secondary problem, a complication of calculi, but also of tumors, scar tissue in the kidney or ureter, and untreated prostatic enlargement. Developmental defects are common in the urinary tract and may cause obstruction by kinking or stenosis of a ureter. Obstructive uropathy can be diagnosed by ultrasonography in the fetus, allowing for immediate or neonatal corrective surgery, thus preventing major kidney damage. Urine is continually forming. Any prolonged interference with urine outflow through the system results in back pressure and a dilated area filled with urine in the ureter or kidney In the kidney, continued buildup of urine, particularly over a prolonged period of time, causes necrosis of the tissue 32  Hydronephrosis Because of direct pressure and compression of the blood vessels. Hydronephrosis is frequently asymptomatic unless mild flank pain occurs as the renal capsule is distended, or unless infection develops. It can be diagnosed with ultrasonography, radionucleotide imaging, CT scan or IVP. If the cause is not removed, bilateral hydronephrosis could lead to chronic renal failure. 33  TUMORS Benign tumors are rare in the urinary tract. Malignant tumors occur primarily after age 50 years, in males by a ratio of 3 : 2. Smoking is a major predisposing factor. Renal Cell Carcinoma ✓ Renal cell carcinoma (adenocarcinoma of the kidney) is a primary tumor arising from the tubule epithelium, more often in the renal cortex. ✓ It tends to be asymptomatic in the early stage and often has metastasized to liver, lungs, bone, or CNS at the time of diagnosis. This cancer occurs more frequently in men and smokers. ✓ The initial sign is usually painless hematuria, either gross or microscopic. ✓ Other manifestations include dull, aching flank pain; a palpable mass; unexplained weight loss; and anemia or erythrocytosis. Paraneoplastic syndromes such as hypercalcemia (increased parathyroid hormone) or Cushing’s syndrome (increased adrenocorticotropic hormone) are common. ✓ This tumor tends to be silent; therefore, diagnosis is made in one third of cases after metastasis to lungs, liver, or bone has occurred. ✓ Removal of the kidney (nephrectomy) is the treatment because the tumor is usually unresponsive to radiation or chemotherapy. 34  Bladder Cancer Malignant tumors of the bladder commonly arise from the transitional epithelium lining the bladder in the trigone area. This cancer often develops as multiple tumors and tends to recur. It is diagnosed by urine cytology (malignant cells in the urine) and biopsy. The tumor is invasive through the wall to adjacent structures, and it metastasizes through the blood to pelvic lymph nodes, liver, and bone. The early sign is hematuria, gross or microscopic. Dysuria or frequency may develop and infection is common. Bladder cancer has a high incidence in individuals working with chemicals in laboratories or industry, particularly with dyes, rubber, and aluminum. More than 50% of patients are cigarette smokers. Other predisposing factors are recurrent infection and heavy intake of analgesics. Treatment includes surgical resection of the tumor in 90% of cases, chemotherapy, and radiation. 35  References: ▪ NORRIS, T. (2019). Porth’s Pathophysiology Concepts of Altered Health States. 10th ed. Wolters Kluwer ▪ Ian Peate, (2021) Fundamentals of applied pathophysiology: an essential guide for nursing & healthcare students. 4th ed. ▪ Hoboken, NJ : Wiley-Blackwell Dignle, M., Mulvihill, M., Zelman, M. & Tompary, E. (2011). Introductory pathophysiology for nursing & healthcare professionals. |Pearson ▪ Nair, M., & Peate, I. (2015). Pathophysiology for nurses at a glance (nursing and healthcare). Publisher: West Sussex, England: John Wiley & Sons, Inc PATH200/MACHS 36