Diseases of the Renal System

Transcription

1 Diseases of the Renal System Chapter 20 1

2 2

3 Kidneys - Anatomy Regulatory and metabolic functions Nephron - functional unit; approx. 1.2 million in each kidney Glomerulus within Bowman s capsule Afferent arteriole carries blood to glomerulus Efferent arteriole - carries blood from glomerulus 3

4 Kidneys - Anatomy Nephron Tubules see Fig Proximal convoluted tubule Loop of Henle Distal convoluted tubule Colleting duct 4

5 5

6 Kidneys - Anatomy Nephron Ultrafiltrate formed by glomerulus Similar to composition of blood Filters large proteins and blood cells Modified by tubules Reabsorption of amino acids, glucose, select minerals, water Secretion of solutes, water 65% of filtered sodium and water reabsorbed (active transport in proximal tubule) 6

7 Kidneys - Anatomy Nephron - functions Maintain extracellular environment for cell function Excretion of waste products of metabolism Maintain fluid, electrolyte and acidbase balance Vasopressin in response to blood volume, maintains fluid balance 7

8 Kidneys - Anatomy Nephron - functions Secretion of hormones that modulate hemodynamics Erythropoietin - red blood cell production Vitamin D bone metabolism 8

9 The Kidneys Diagnostic Procedures GFR - glomerular filtration rate; rate at which substances are cleared from plasma normal L/day Clearance calculations see p. 613 Tubular function tests Microscopic evaluation of the urine Radiologic evaluation (IVP, MRI, ultrasound) Biopsy 9

10 Nephrotic Syndrome Deficiency of albumin in blood and its excretion in the urine d/t altered glomerular function large-molecule proteins and RBCs leak into urine Proteinuria >3.5 Hyperlipidemia Hypoalbuminemia Result of underlying disease More prevalent in children 10

11 Nephrotic Syndrome Clinical Manifestations Frothy urine Anorexia, malaise, puffy eyelids, abdominal pain, muscle wasting Anascarca with ascites, plural effusion Altered blood pressure Oliguria d/t hypovolemia Edema Loss of zinc, copper, vitamin D; iron bound to proteins lost 11

12 Nephrotic Syndrome Treatment Treat underlying cause Reduce cholesterol Control blood pressure Reduce protein in urine ACE inhibitors and ARBs Check potassium levels 12

13 Nephrotic Syndrome Nutrition Therapy See Table 20.1 Control intake of protein g/kg/day Soy- or flaxseed-based proteins Protein supplementation no benefit 13

14 Chronic Kidney Disease (CKD) Syndrome in which progressive loss of kidney function occurs Not reversible Progression to end-stage renal disease (ESRD or CKD stage 5) Renal replacement therapy or transplant Requires medication and specialized diet 14

15 Chronic Kidney Disease (CKD) Risk factors Proteinuria Ethnicity African American with diabetes highest Gender males Smoking Heavy consumption of non-narcotic analgesics Obesity??? 15

16 Chronic Kidney Disease (CKD) Most frequent causes Diabetes Hypertension Glomerulonephritis Hereditary and cystic congenital renal disease Interstitial nephritis Neoplasm/tumor 16

17 Chronic Kidney Disease (CKD) Common complications Malnutrition CVD aggressive management recommended Bone and mineral disorders Anemia 17

18 Chronic Kidney Disease (CKD) Stages see Table 20.2 Stages 1 & 2 kidney damage with: Normal or increased GFR, mild decrease in GFR Stage 3 Moderate decrease: GFR ml/min Stage 4 Severe decrease: GFR ml/min Stage 5 Inadequate to sustain life 18

19 Chronic Kidney Disease (CKD) Pathophysiology Advanced impairment in control of fluid and electrolyte balance Uremia, hyperphosphatemia, azotemia, oliguria Kidney function < 15 ml/min Sodium retention, edema, hypertension Metabolic acidosis Hyperkalemia 19

20 Chronic Kidney Disease (CKD) Pathophysiology Microcytic anemia and iron deficiency Inadequate erythropoietin Renal osteodystrophy d/t impaired intestinal calcium absorption and secondary hyperparathyroidism 20

21 21

22 Chronic Kidney Disease (CKD) Treatment Treat underlying disease, delay progression Stages 1 & 2 EPO replacement, vitamin D supplementation Stage 5 renal replacement therapy, nutrition therapy crucial, transplant Post transplant immunosuppresants 22

23 Chronic Kidney Disease (CKD) Renal Replacement Therapy - Dialysis removal of excessive and toxic by-products of metabolism from the blood, replacing the filtering function of the kidney Fluid and electrolyte balance must be maintained Passing blood across selective membrane exposed to rinsing fluid (dialysate) 23

24 CKD - Renal Replacement Therapy Serum creatinine 6 mg/dl for nondiabetics or Creatine clearance < 15 ml per minute for diabetics Definite indicators: Pericarditis, uncontrolled fluid overload, pulmonary edema, uncontrolled and repeated hyperkalemia, coma, lethargy 24

25 CKD - Renal Replacement Therapy Hemodialysis (HD) or Peritoneal Dialysis (PD) Type based on underlying kidney disease and co-morbid factors See Box role of health team Both require selective, permeable membrane Allows passage of water and small molecules Excludes larger molecules such as protein 25

26 CKD - Renal Replacement Therapy Hemodialysis(HD) Membrane is manmade dialyzer artificial kidney See Fig. 20.5, 20.7 Preferred access site AVF, AVG Typical regimen 3 days/week for 4 hrs/treatment 26

27 27

28 28

29 CKD - Renal Replacement Therapy Peritoneal dialysis (PD) Lining of patient s peritoneal wall is the selective membrane see Fig Types CAPD - continuous ambulatory CCPD - continuous cycling Access via catheter into peritoneal cavity Range of dextrose concentrations Dwell time and number of exchanges 29

30 30

31 CKD - Stages 1 & 2 Nutrition Therapy Focus on co-morbid conditions: diabetes, hypertension, hyperlipidemia, progression of CVD K/DOQI guidelines for GFR 20 SGA every 1 3 mo. Dietary interviews and food intake, or npna every 3-4 mo. More frequent if GFR 15 Protein: g/kg Energy: kcal/kg 31

32 CKD - Stages 3 & 4 Nutrition Therapy See ADA guidelines Nutrition assessment recommendations see p. 624 Nutrient recommendations see Table 20.4 Protein (inc), energy, sodium (dec), potassium, phosphorus, calcium, vitamins, minerals, fluid may need adjustment Emphasize usual foods 32

33 CKD - Stages 3 & 4 Outcome measures Clinical Biochemical see Table 20.3 Anthropometrics Clinical signs and symptoms Behavioral Meal planning, meeting nutrient needs, awareness of food/drug interactions, exercise See Table

34 CKD - Stage 5 Nutrition Assessment On dialysis measures not different Dietary intake Biochemical: serum albumin See Table 20.7 for other indicators Goals: meet nutritional requirements, prevent malnutrition, minimize uremia, minimize complications Maintain blood pressure, fluid status 34

35 CKD - Stage 5 Nutrition Intervention HD high in protein, control intake of potassium, phosphorus, fluids and sodium Modifications in fat, cholesterol, TG if warranted PD more liberalized; higher in pro., sodium, potassium and fluid, limit phosphorus See Table 20.8 nutrients to monitor 35

36 CKD - Stage 5 Nutrition Intervention Protein g/kg (HD), at least 50% HBV PD same except during peritonitis increase protein Losses increase % and may remain elevated 36

37 CKD - Stage 5 Nutrition Intervention Energy to prevent catabolism; needs slightly higher; individualized PD - account for kcal in dialysate Caloric load PET Box kcal/kg/day average intake 37

38 CKD - Stage 5 Nutrition Intervention Adjusted Edema-Free Body Weight should be used to calculate body weight for calculating protein and kcal For those < 95% or > 115% median standard weight NHANESII For maintenance in HD and PD pts. Obtained postdialysis for HD pts., and after drainage for PD patients 38

39 CKD - Stage 5 Nutrition Intervention Fat - increased risk for CAD and stroke HD typically have normal LDL, HDL, TG PD higher TC, LDL, TG Recommend TLC diet guidelines for both 39

40 CKD - Stage 5 Nutrition Intervention Fluid and Sodium highly individualized based on residual urine output and dialysis modality Interdialytic weight gain (HD) should not exceed 5% of body weight 2 gram sodium diet Not more than 1 L fluid daily If urine output > 1 L/day sodium and fluid can be liberalized to 2-4 g and 2 L 40

41 CKD - Stage 5 Nutrition Intervention Fluid and Sodium PD based on ultrafiltration; kg fluid/day Fluid 2 L Sodium 2-4 g Fluid overload: shortness of breath, htn., CHF, edema 41

42 CKD - Stage 5 Nutrition Intervention Phosphorus Hyperphospatemia - GFR ml/min Dietary phosphorus restriction: mg/day, < 17 mg/kg body IBW See Table Phosphate binders; calcium salts Limit calcium intake 42

43 CKD - Stage 5 Nutrition Intervention Calcium requirements higher in CKD Restrict foods high in calcium Take supplements on empty stomach Limit to 2000 mg/day from all sources 43

44 CKD - Stage 5 Nutrition Intervention Vitamin Supplementation Water-soluble vitamins Daily requirements Table Renal vitamins include B 12, folic acid, vitamin C Avoid high doses of vitamins A & C May need vitamin K if on antibiotics 44

45 CKD - Stage 5 Nutrition Intervention Mineral supplementation Avoid Mg-containing phosphate binders, antacids, and supplements Iron Zinc 45

46 Comorbid Conditions - Nutrition Therapy Cardiovascular Disease - more likely to die from CVD than progress to Stage 4 CKD Heart failure, LVH, atherosclerosis Accelerated atherogenesis Other non-traditional risk factors Elevated CRP 46

47 Comorbid Conditions - Nutrition Therapy Secondary Hyperparathyroidism (SHPT) Can progress to severe, intractable forms of bone disease Prolonged PTH exposure osteitis fibrosa More prone to fracture Restrict dietary phosphorus Supplementation of vitamin D 47

48 Comorbid Conditions - Nutrition Therapy Anemia d/t low Hgb from inadequate endogenous erythropoietin Treatment with rhuepo and iron 48

49 Medicare Coverage for MNT Part B Medicare, renal disease dg of GFR ml/min or kidney transplant qualify Dialysis patients excluded 49

50 Post Transplant Nutrition therapy differs between: Acute phase up to 8 weeks Chronic phase after 9 weeks See Table for summary 50

51 Post Transplant Protein and Energy Increased for up to 6 8 weeks After 8 weeks: RDA for protein and low in saturated fat Carbohydrate Glucose intolerance common; insulin or OHA may be warranted Emphasize dietary fiber 51

52 Post Transplant Fat Low-fat diet Sodium Hypertension common; restrict sodium Potassium Potassium restriction in acute period 52

53 Post Transplant Immunosuppressants Used to prevent acute rejection Avoid grapefruit and grapefruit juice Cardiovascular Disease TLC Lipid-lowering agents Hypomagnesemia Supplementation of Mg to lower LDL and apolipoprotein B 53

54 Post Transplant Obesity Weight gain common; may complicate hyperlipidemia and glucose intolerance Emphasize diet, behavior modification, exercise 54

55 Post Transplant Calcium, Phosphorus, Altered Bone Metabolism Osteoporosis and altered vitamin D Hypercalcuria from corticosteroids Supplement with calcium, vitamin D, anti-resorptive agents Increase phosphorus Monitor serum potassium 55

56 Acute Renal Failure ARF - when kidneys suddenly stop functioning and abrupt cessation or reduction in GFR and accumulation of nitrogenous wastes occurs Stress or injury induced hypercatabolic state Status declines rapidly, loss in lean body mass, toxicity-related symptoms 56

57 Acute Renal Failure Clinical manifestations Fluid and electrolyte disorders, azotemia, wasting Electrolytes increases or decreases in potassium, Mg, phosphorus; monitor frequently BUN and creatinine elevated even if ratio is normal; maintain BUN mg/dl 57

58 Acute Renal Failure Treatment Treat underlying cause Nutrition therapy depends on type of dialysis or CRRT 58

59 Acute Renal Failure Nutrition Implications Trace Minerals and Vitamins May develop trace mineral toxicity Daily infusion not recommended Vitamins A, D, K and C may need to be adjusted Triglycerides May need lipid-free formula 59

60 Acute Renal Failure Nutrition Interventions Energy and protein May need enteral nutrition Protein.6 to 1.4 g/kg/d; essential and nonessential amino acids Kcal kcal/kg/d 60% CHO, 20-35% fat TPN > 5 days; g lipids as emulsion 60

61 Acute Renal Failure Nutrition Interventions Fluid status should be monitored Supplementation of minerals, electrolytes, and trace elements Monitor serum and urine levels Vitamin A not recommended Vitamin K recommended B 12 ; 10 mg pyridoxine Limit ascorbic acid to mg/d 61

62 Nephrolithiasis Kidney stones form when calcium, oxalate or uric acid in urine in higher than normal amounts Can become lodged in urinary tract and obstruct urine flow Typically consist of calcium salts, cystine, uric acid or struvite 62

63 Nephrolithiasis Risk factors: family hx, hypercalciuria, hyperuricosuria, hyperoxaluria and low urine volume Other causes: gout, excess intake of vitamin D, UTIs, and urinary tract blockages Asymptomatic until blockage occurs Acute pain, hematuria, nausea, vomiting, pain with urination, urgency to urinate 63

64 Nephrolithiasis Treatment/Nutrition Therapy Most can pass with plenty of fluid and pain medications Medical procedures if unable to pass ESWL most common Increase fluid intake by 3 L/day in divided doses Avoid calcium supplementation, dairy OK 64

65 Nephrolithiasis Treatment/Nutrition Therapy Limit oxalate intake to mg/d Avoid foods that increase urinary oxalate beets, chocolate, cola, coffee/tea, nuts, berries, wheat bran, spinach, rhubarb 65