Urinary system disorders Chapter 29

Transcription

1 Urinary system disorders Chapter 29 1

2 The Nephron Anatomy 2

3 Physiology 1.25 L per minute blood flow 25% of Cardiac Output Kidney compensates if one is lost - 2 weeks 3

4 Urine Formation 1. Filtration 2. Reabsorption w Diffusion w Osmosis w Active Transport 3. Secretion w Diffusion w Osmosis w Active Transport 4. Excretion 4

5 Glomerular Filtration w Driven by pressure through glomerular membrane 5

6 Glomerular Filtration w Through 3 Selectively Permeable Layers w Capillary endothelium w Basement membrane w Epithelium of Bowman s capsule w podocytes 6

7 Glomerular Filtration w Basement Membrane w Selective Filter w Slightly porous w Repels proteins (negative charge) w Allows only water, ions, and small molecules 7

8 Renin-Angiotensin-Aldosterone System Angiotensinogen Renin Angiotensin I ACE Vasoconstriction Efferent Arterioles Systemic Arteries Angiotensin II Aldosterone Release 8

9 Renin-Angiotensin-Aldosterone System 9

10 Renal Cystic Disease w Fluid filled sacs or Dilated nephrons w Four types w Simple kidney cysts w Acquired cystic disease w Medullary sponge kidney w Polycystic kidney disease w Result of tubular obstruction w Enlarging cysts w Compresses vessels and renal tissue 10

11 Polycystic Kidney Disease w Autosomal dominant disorder characterized by multiple bilateral grapelike cysts that enlarge and replace functioning kidney tissue w Grossly enlarged kidneys w Slowly progressive w Destruction of renal tissue 11

12 Polycystic Kidney Disease w Complications w Pain from enlarging cysts w Hematuria from bleeding into a cyst w Pyelonephritis from ascending UTI w Hypertension due to compression of intrarenal blood vessels and activation of R-A-A System w End stage renal failure after age 40 12

13 Polycystic Kidney Disease w Diagnosis and Treatment w Ultrasonography w Abdominal CT scanning w Supportive treatment w Control hypertension w Prevention of ascending UTIs w Dialysis and Transplant 13

14 Obstruction w Urine accumulates behind blockage w Infection w Damage due to backpressure w Classification w Site of obstruction w Degree of obstruction w Duration of obstruction 14

15 Obstruction w Site of Obstruction w Renal Pelvis w Ureter w Bladder and Urethra 15

16 Obstruction w Common Causes of Obstruction w Stones (Renal Calculi) w Pregnancy w Ureteral Stricture w Prostatic Hyperplasia or Cancer 16

17 Obstruction w Mechanisms of Damage w Stasis of urine w infection w stone formation w Back pressure w interferes with blood flow w destroys renal tissue w kidney atrophies 17

18 Obstruction w Back Pressure (location is important) w Urethral Obstruction w Accommodated in the bladder w Mild discomfort, Frequency w Bladder or Ureter Obstruction w More severe w Pressure can irreversibly stretch the ureters and renal pelvis w (hydroureter & hydronephrosis) w May alter tubular transport and compromises blood flow to the kidney 18

19 Hydronephrosis 19

20 Obstructive Disorders w Clinical Features w Vary depending on site, cause and rapidity of onset w Pain w UTIs w Indications of Renal Dysfunction w Hypertension 20

21 Kidney Stones w Most Common Cause of Obstruction w Nephrolithiasis stone within the kidney w Urolithiasis stone anywhere in the urinary system w Calcium Stones are Most Common w Theories of Stone Formation? w Calcium: idiopathic, hypercalciuria, alkaline urine w Struvite: from urease-producing bacteria, acidic urine w Contributing Factors w immobilization w bone disease w vitamin D intoxication w decreased fluid intake 21

22 Staghorn Kidney Stones 22

23 Renal Colic w Pain that accompanies urinary obstruction caused by kidney stones w Symptoms: acute, intermittent, excruciating, upper quadrant/flank pain that may radiate to other areas; nausea/vomiting; cool, clammy skin 23

24 Lower Urinary Tract Obstruction w Neurogenic bladder often due to injury of urinary system or neurologic dysfunction w Dyssynergia : dyscoordination of the detrusor muscles of the bladder and the external urethral sphincter muscles w Detrusor hyperreflexia: AKA overactive bladder. Lesions above C2, pontine micturation center, upper motor neuron disease, Guillain-Barre w Detrusor areflexia: muscle fails to contract in response to the stretch of filling urine. MS, spinal lesion below S1, lower motor neuron disorder 24

25 Urinary Tract Obstruction w Compensatory hypertrophy: the functional side increases in size and makes up for the loss of function on the other side. Due to w Obligatory growth: due to growth hormone w Compensatory growth: hormones unknown w Postobstructive diuresis:large increase in excretion of urine after obstruction is removed 25

26 Urge incontinence: I feel like I need to go but the bladder is not as full as it feels, maybe nervous or inflammatory stimulus Stress incontinence: weak muscles and fascia so coughing, laughing, jumping results in urine leaks Overflow incontinence: bladder is just too full to hold that much urine, you waited too long to void Functional incontinence: urinary system and nerves going to and from it work, but you are cognitively demented (Alzheimer s) 26

27 Urinary Tract Infections w Etiology w Escherichia coli (E. coli) w Any microorganism that has contaminated or colonized in the urethra, vaginal or perineal area can cause an UTI 27

28 Urinary Tract Infections Acute Cystitis Lower UTI of the bladder Symptoms: increased frequency of urination, burning & pain on urination, lower abdominal discomfort Also associated with urethritis or vaginitis Acute Pyelonephritis Upper UTI that affects the tubules and interstitium of the kidneys Bacterial infection caused by catheterization and urinary instrumentation, vesicoureteral reflux, pregnancy, neurogenic bladder 28

29 Urinary Tract Infections w Host Defenses w Washout phenomenon w Protective mucin layer of the bladder and urethra w Estrogen may play a role in women w Local immune response w IgA as an antibacterial defense w Prostatic secretions in men w Genetic polymorphism increases E. coli ability to attach in some women 29

30 Urinary Tract Infections Women Shorter urethra Urethra proximity to openings of vagina and rectum leads to easy contamination Hormonal and anatomical changes during puberty and sexual activity contribute to UTI Common during pregnancy Men Longer urethra Prostatic secretions help protect from UTI until age 50 when prostatic hypertrophy leads to obstruction and UTI 30

31 Urinary Tract Infection (UTI) w Nonbacterial infectious cystitis: viral, fungal, chlamydia w Interstitial cystitis: cause??? unknown, though several theories have been put forward (these include autoimmune theory, nerve theory, mast cell theory, leaky lining theory, infection theory and a theory of production of a toxic substance in the urine. Other theories are neurologic, allergic, genetic and stress-psychological w Manifestations w Most common in women 20 to 30 years old w Bladder fullness, frequency, small urine volume, chronic pelvic pain w Treatment w No single treatment effective, symptom relief 31

32 Glomerulonephritis w Bilateral inflammation of the glomeruli w Most common cause of chronic renal failure w Uncertain cause but immune mechanism is likely (Type 2 cell lysis Strep A ab, Type 3 SLE immune complex) w Injury to Glomeruli (Glomerulopathies) w Allows Proteins to enter tubules with filtrate w Proteinuria w Allows RBC s to enter tubules with filtrate w Hematuria 32

33 Glomerular Disorders w Increased glomerular capillary permeability and loss of negative ionic charge barrier result in passage of plasma proteins into the urine w Resulting hypoalbuminemia encourages plasma fluid to move into the interstitial spaces w Edema 33

34 Structure of the Glomerulus w Glomerular capillaries and Bowman s capsule are both made of epithelial cells sitting on a basement membrane w They are so tightly attached to each other that they share one basement membrane w The epithelial cells of Bowman s capsule stand up from the basement membrane on foot processes, leaving pores between the feet for filtration Urine Epithelial cell Foot processes Basement membrane Blood in capillary 34

35 Immune Damage to the Glomerulus Antibodies to glomerular basement membrane proteins Circulating immune complexes lodge in glomerular membrane 35

36 Acute Proliferative Glomerulonephritis w The most common form of glomerulonephritis w Follows infections caused by strains of group A Strep w Inflammatory response due to an immune reaction w Capillary membrane swells w Becomes permeable to plasma proteins and cells w Also called post-streptococcal glomerulonephritis w Occurs 7 12 days post infection w Oliguria is first sign followed by proteinuria and hematuria w Approximately 95% full recovery - spontaneously 36

37 Glomerulonephritis w Rapidly progressing glomerulonephritis w Antiglomerular basement membrane disease (Goodpasture syndrome: glomerulonephritis and hemorrhaging of the lungs), autoimmune Type II hypersensitivity reaction w Chronic glomerulonephritis, diabetes mellitus, SLE 37

38 Rapidly Progressive Glomerulonephritis w Unknown cause w Perhaps - immunologic mechanism w Immune complex: Strep A w Anti-glomerular membrane: Goodpasture s w Rapidly progressive w Treatment w Plasmapheresis w Immunosuppressive drugs 38

39 IgA Nephropathy w Primary glomerulonephritis w IgA containing immune complexes w Unknown cause w Possible defect in IgA molecule w Slowly progressive w No known treatment 39

40 Nephritic Syndrome w Glomerular disorders in which inflammatory process damages the glomerular membrane w Mild protein loss w Red and white blood cells escape into the urine w Hematuria with red and white cell casts w Hemodynamic changes can decrease permeability of glomerular membrane and decreases the GFR w Low proteinuria 40

41 Nephritic Syndrome w Complications w Renal Failure w Pulmonary edema w Heart failure w Hypertension 41

42 Nephrotic Syndrome w Collection of clinical findings associated with glomerular disease characterized by marked proteinuria, hypoalbuminemia, hyperlipidemia and edema w Increased glomerular permeability causes massive loss of plasma proteins w proteinuria w Edema is common w Hypoalbuminemia allows plasma to leak into tissues w Reduced intravascular volume lowers GFR triggering Angiotensin II and Aldosterone which increase sodium and water retention 42

43 Nephrotic Syndrome w Other proteins lost in urine: Immunoglobulins and complement à immune suppression Clotting and anti-clotting proteins à thrombosis Proteins that carry other blood components à imbalances in blood components; altered drug dosages 43

44 Nephrotic Syndrome Glomerular Damage Permeability to Protein Proteinuria > 3.5 g/24hr Hypoproteinemia (Albumin < 3 g/100ml) Compensatory Protein Synthesis including Lipoproteins Plasma Osmotic Pressure Hyperlipidemia Plasma leaks into tissues Plasma Volume GFR ñ Na / Water Retention EDEMA Aldosterone 44

45 Nephrotic Syndrome w Complications w Malnutrition w Infection w Coagulation disorders w Thromboembolic vascular occlusion w Accelerated atherosclerosis w Acute renal failure 45

46 Nephrotic Syndrome w Treatment w Correct underlying cause w Diuretics 46

47 Nephrotic Syndrome w Membranous glomerulonephritis:one of the more common forms of nephrotic syndrome. Caused by immune complexes binding to the glomerular basement membrane w Focal glomerulosclerosis: common in kids, scarring of some of the glomeruli, there are several genetic causes w Minimal change disease (lipoid nephrosis): in kids, cause is idiopathic, diffuse loss of (podocyte) foot processes., vacuolation, and growth of microvilli on the visceral epithelial cells. 47

48 Tubulointerstitial Disorders w Damage to tubules and surrounding tissues w Generally due to: w Pyelonephritis w Toxic substances such as medications or ischemic injury w Urinalysis is neither nephrotic nor nephritic in Character w Mild Proteinuria ( < 1 gm/day ) 48

49 Renal Failure w Inability of kidney to maintain homeostasis and eliminate nitrogenous wastes w Decline in GFR leading to azotemia w Creatinine w Urea w Generally a decline in urine output w Oliguria = < 500 ml/day w Anuria = < 100 ml/day w Non-oliguric failure is possible 49

50 Acute Renal Failure w Sudden interruption of renal function w Classified as prerenal, postrenal & intrarenal w Often reversible if treated early w Three phases w Oliguric phase w Diuretic phase w Recovery phase 50

51 Acute Renal Failure w Oliguric phase w Lasts for a few days to several weeks w Urine output drops to below 400 ml/day w Patient may become fluid overloaded w Cellular injury and necrosis of kidney w Diuretic phase w Lasts days to weeks w Kidneys become unable to conserve sodium & water w Urine output increases 51

52 Acute Renal Failure w Recovery Phase w Lasts 3 to 12 months w Renal function gradually returns to normal 52

53 Acute Renal Failure w Prerenal failure: most common w Caused by diminished blood blow to the kidney w Kidney becomes ischemic w Damages kidney tubules 53

54 Acute Renal Failure w Intrinsic failure (intrarenal failure) w Damage to the filtering structures of the kidney w May be nephrotoxic, inflammatory or ischemic 54

55 Acute Renal Failure w Postrenal failure w Bilateral obstruction to urine outflow 55

56 Acute Renal Failure Causes of Acute Renal Failure Prerenal Hypovolemia Decreased vascular filling Heart failure Vasoconstrictive drugs Postrenal Bilateral ureteral obstruction Bladder outlet obstruction Intrinsic (ATN) Prolonged ischemia Nephrotoxins Acute renal disease 56

57 Acute Renal Failure w Complications w Infection w Heart failure w Hypertensive crisis w Electrolyte imbalance w Diagnostic test findings w Elevated BUN, creatinine and potassium w Abnormal urinalysis 57

58 Acute Renal Failure w Treatment w Reverse the cause w Electrolyte and I.V. therapy 58

59 Acute Tubular Necrosis w Intrarenal acute renal failure w Injury to the nephron s tubular segment w Resulting from ischemia or nephrotoxic injury 59

60 Acute Tubular Necrosis w Causes w Ischemic injury w Hypotension w Trauma, hemorrhage, dehydration w Shock w Nephrotoxic injury w Toxic chemical ingestion or inhalation w Hypersensitivity reaction to antibiotics etc. 60

61 Acute Tubular Necrosis w Pathophysiologic Changes w Decreased urine output, hyperkalemia and elevated renal function tests w Complications w Heart failure w Pulmonary edema w Anorexia and vomiting 61

62 Acute Tubular Necrosis w Diagnostic test findings w Abnormal urinalysis w Abnormal blood tests of renal function w Treatment w Reverse cause w Long term fluid management 62

63 Chronic Renal Failure w End result of gradual tissue destruction and loss of renal function w Occasionally due to acute destruction of kidney w Fatal without treatment w Nephron damage is progressive and permanent w Relatively asymptomatic until 75% loss of nephrons 63

64 Chronic Renal Failure w w w w Diminished renal reserve w Nephrons are working as hard as they can w GFR is 50 89% of normal Renal insufficiency w Nephrons can no longer regulate urine density w GFR is 20 50% of normal Renal failure w Nephrons can no longer keep blood composition normal w GFR is 5 20% of normal End-stage renal disease w GFR is Less than 5% of normal 64

65 Chronic Renal Failure w As GFR decreases azotemia and uremia develops w Azotemia = accumulated nitrogenous wastes in blood w Early asymptomatic sign of renal failure w Elevated BUN w Uremia = urea and other nitrogenous wastes increase in blood w Constellation of symptoms due to systemic complications attributed chronic renal failure (increased BP, edema, nausea, vomiting, neurological problems due to toxic levels of nitrogenous wastes) w These appear when azotemia becomes significant 65

66 Chronic Renal Failure w Renal filtering function decreases w Altered fluid and electrolyte balance w Acidosis, hyperkalemia, salt wasting, hypertension w Wastes build up in blood w Increased creatinine and BUN w Toxic to CNS, RBCs, platelets w Kidney metabolic functions decrease w Decreased erythropoietin w Decreased Vitamin D activation 66

67 Chronic Renal Failure These are not usually seen in Acute Renal Failure Body System Hematologic Cardiovascular Gastrointestinal (GI) Musculoskeletal Neurologic Body fluids Genitourinary Manifestations Anemia, bleeding tendencies, immunocompromised Hypertension, CHF, pulmonary edema, arrhythmias Anorexia, nausea, vomiting, GI bleeding Muscle weakness, bone pain, spontaneous fractures Headache, anorexia, lethargy, delirium, coma, seizures Metabolic acidosis, hyperkalemia, hypocalcemia Impotence, amenorrhea, loss of libido 67

68 Chronic Renal Failure w Causes w Endocrine disease (diabetes) w Chronic glomerular disease (glomerulonephritis) w Chronic infection w Congenital anomalies w Vascular disease (hypertension etc.) w Obstruction w SLE 68

69 Chronic Renal Failure w Treatment w Low protein, high calorie, fluid restricted diet w Medications w Dialysis w Kidney transplant 69

70 Acute Renal Failure (ARF) 70

71 Chronic Renal Failure 71

72 Tumors w Renal tumors w Renal adenomas w Renal cell carcinoma (RCC) w Bladder tumors w Transitional cell carcinoma w Gross, painless hematuria w Most common in males older than 60 years w Chronic heavy smokers 72