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MNT for Renal Disorders

MNT for Renal Disorders

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MNT for Renal Disorders

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  1. MNT for Renal Disorders ND 437/537 Chapter 39 Karen White, MS, RD, LDN

  2. Renal Outline • Functions of the kidneys • Normal urine output • Nephrotic syndrome • Nephritic Syndrome • Acute renal failure • ESRD & Characteristics of renal failure • Dialysis & lab values for assessment with ESRD • MNT • Kidney stones

  3. Functions of the Kidneys • Filtration of blood: remove fluid and wastes (NH3, urea, Cr, P, Na, K, H+,water) • maintain blood pressure: secrete renin (in response to  BV) to stimulate the angiotensin system (vasocontstriction),  aldosterone (Na reabsorption)   BP • secrete erythropoietin - a hormone needed for rbc production • Ca-P homeostasis by activating vitamin D & excreting Ca & P

  4. Filtration Filtration: • filtration (into tubules) • reabsorption • secretion • 125 ml ultrafiltrate made per minute • 124 ml reabsorbed • 1 ml urine per minute x 60 x 24 = 1500 ml urine/d • kidneys control the amount of water, electrolyes, acid, P, & Nitrogenous wastes excreted • our 3L of blood is filtered over & over 500x/d!

  5. Filtration, continued • Each kidney has ~ 1 million nephrons, which consist of the glomerulus connected to tubules • Glomerulus = capillary mass surrounded by a membrane, Bowman’s capsule. • Glomerulus produces 180 L ultrafiltrate/d, which the remaining tubules modify through reabsorption & secretion. • Ultrafiltrate  blood – blood cells & proteins • Filtration is passive & relies on perfusion pressure • Tubules reabsorb most of ultrafiltrate, leaving 1.5L urine/d. Reabsorption is active.

  6. Urine Production - Filtration, cont. • Normal glomerular filtration rate (GFR) 125ml/min • Urine can be very dilute (50 mOsm) or very concentrated (1200 mOsm) depending on the concentration of wastes in the blood and the amount of water in which to dilute the waste • Minimum urinary volume to excrete wastes of a fixed concentration (600 mOsm) is 500 ml! • Urine output of < 500ml/d = oliguria • Anuria = no urine output (< 50ml/d)

  7. Nephritic Syndrome aka glomerulonephritis Nephrotic syndrome Both of the these conditions are characterized by an impairment in the integrity of the glomerulus, which allows inappropriate components to pass into the filtrate & thus the urine. Renal failure, in contrast, is a decrease in the ability to filter blood. Glomerular Diseases

  8. Nephritic Syndrome (glomerulonephritis) • inflammation of capillary loops of glomerulus. • Characterized by: • hematuria - loss of glomerular barrier to blood cells, • HTN • mild  renal fxn • Etiology: streptococcal infection is most common. • usually completely resolve (quickly), but can progress to nephrotic syndrome or even ESRD. • MNT: Na restriction with HTN. Otherwise, maintain good nut'l status & hope it resolves. NO need to restrict protein or potassium (K).

  9. Loss of the glomerular barrier to protein. (Filter's holes became too large) Characterized by proteinuria, hypoalbuminemia, edema & hyperlipidemia. Dx by proteinuria Etiology: diabetes, lupus, amyloidosis, & other diseases of the kidneys. Can be chronic, and occasionally can progress to CRF. MNT: goal is to replenish albumin w/o exacerbating proteinuria. 0.8 gm/kg – ¾ HBV  calories (35cal/kg+)  Na mildly (2400 - 3000 mg/d) with edema normal fluid b/c blood vol  with  albumin if chronic,  saturated fat. can give albumin IV. Nephrotic Syndrome

  10. Acute Renal Failure (ARF) • Sudden  in GFR & thus  ability of kidneys to excrete wastes. • Can occur with oliguria or a normal urine flow! • Duration: few days – several weeks • mortality: varies greatly depending on cause: very low with drug toxicity, up to 70% with trauma or sepsis. • causes: see Box 39-1 pg. 967 (severe dehydration, trauma, sepsis, toxicity from drugs, glomerularnephritis, obstruction d/t prostate cancer or hypertrophy, etc.)

  11. ARF – typical progression • Anuria or oliguria • Recovery • Increase in urine output, but still not filtering wastes • Gradual recovery in waste filtration & excretion

  12. MNT for ARF • protein: • oliguric phase -  (0.5 - 0.8) • diuretic phase or dialysis - (0.8 - 1.0) • calories: 30-40 cal/kg of dry weight (fluid retention) • fluid, Na, K • oliguric phase  • fluid: output + 500ml (monitor I/O!) • Na 500mg - 1g (20-40 mEq) -------- • K 1200 - 2g (30-50 mEq) • diuretic phase - replace losses (monitor labs; gradually progress to normal diet) • Patients often “fed” parenterally initially when N/V mEq = mg  atomic wt x valence atomic wt of Na = 23 atomic wt of K = 39

  13. Progressive Nature of Renal Failure • Once 2/3 - ¾ of kidney function is lost, further loss will ensue, and ESRD is unavoidable. • Sometimes progression to ESRD is rapid • Other times progression can take months – years, with persons in pre-end-stage renal disease for a long time. • 90% of ESRD is caused by: • DM • Glomerulonephritis • HTN

  14. fluid retention (edema)  Na, K (irregular heartbeat)  H - acidosis  BP  Hct (anemia)  vit D conversion renal osteodystrophy: Calcium pulled from bones (b/c  Ca abs & to P balance with  P excretion), Ca & P precipitate and are deposited on blood vessels!  BUN, Cr, NH3 - build up of N2 wastes = azotemia  uremia: Malaise, weak N/V muscle cramps, itching anorexia, dysguesia neurologic/cognitive impairment. Happens when BUN > 100, Cr 10-20. Cr > 8 qualifies for dialysis (6 if DM) Correlates with GFR < 10 ml/min. Characteristics of Chronic Renal Failure (CRF)

  15. Transplant Dialysis: separating substances in a solution by selective diffusion using semi-permeable membrane. Hemodialysis Peritoneal dialysis CAPD CCPD – multiple exchnages at night by a machine; one exchange during the day Hemodialysis blood passes through semi-permeable membrane of artificial kidney & waste produces are removed by diffusion. 3-5 hours 3x/wk Peritoneal dialysis diffusion carries wastes from the blood through the semi-permeable peritoneal membrane and into dialysate solution that is infused into the peritoneal cavity. The dialysate = sugar water. CAPD - exchange solution 4-5x/d everyday. More efficient but less common Medical Treatment for ESRD

  16. Hemodialysis vs. Peritoneal dialysis

  17. MNT for Pre-ESRD, Hemodialysis, Peritoneal Dialysis Pre-ESRD Hemodialysis CAPD or CCPD Protein (g/kg) 0.6-0.8 1.0-1.2 1.2-1.5 Energy 35-40 30-35 25+ (kcal/kg IBW) Phosphorus 8-12 <17 <17 (mg/kg IBW) Sodium 1000-3000 2000-3000 2000-4000 (mg/d) Potassium Unrestricted ~ 40 Unrestricted (mg/kg IBW) Fluid Unrestricted 500-750 + 2000 + (ml/d) urine output (1000 if anuric) Calcium 1200-1600 based on serum based on serum (mg/d) level level In General most strict most liberal

  18. Monitor Patient Status 1. BP >140/90 2. Edema 3. Weight changes 4. Urine output 5. Urine analysis: • Albumin • Protein

  19. Monitor Patient Status—cont’d 6. Kidney function • creatinine clearance • Glomerular filtration rate (GFR) 7. Blood values • BUN 10 to 20 mg/dl (<100 mg/dl) • Creatinine 0.7 to 1.5 mg/dl (10-15 mg/dl) • Potassium 3.5 to 5.5 mEq/L • Phosphorus 3.0 to 4.5 mg/dl • Albumin 3.5-5.5 g/dl • Calcium 9-11 mg/dl • See table 39-5 p 977-979 for more info on lab values

  20. Kidney Transplant 1. Types: related donor or cadaver 2. Posttransplant management: Corticosteroids Cyclosporine 3. Diet while on high-dose steroids: 1.3 to 2 g/kg BW protein 30 to 35 kcal/kg BW energy 80 to 100 mEq Na 4. Diet after steroids: 1 g/kg BW protein Kcal to achieve IBW Individualize Na level

  21. Kidney Stones - Nephrolithiasis • Ca salts (Ca oxalate or Ca phosphate) • Uric acid • Cystine • Ca salts —Rx: high fluid; evaluate calcium from diet; may need more! • Calcium intake & kidney stones inversely related! • low-oxalate diet may be needed (avoid rhubarb, spinach, strawberries, chocolate, wheat bran, nuts, beets & tea) Apndx 45 • acid-ash diet is sometimes useful but not proven totally effective

  22. Kidney Stones—cont’d 4. Uric acid stones Alter pH of urine to more alkaline Use high-alkaline-ash diet 5. Cystine stones (rare)

  23. Acid-Ash Diet • Increases acidity of urine (contains chloride, phosphorus, and sulfur) • Meats, cheese, grains emphasized • Fruits and vegetables limited (exceptions are corn, lentils, cranberries, plums, prunes)

  24. Alkaline-Ash Diet • Increases alkalinity of urine (contains sodium, potassium, calcium, and magnesium) • Fruits and vegetables emphasized (exceptions are corn, lentils, cranberries, plums, prunes) • Meats and grains limited

  25. Pyelonephritis (UTI) • High fluid intake • Cranberry juice can decrease bacteria

  26. Foods high in potassium • Fruits and vegetables • potatoes, legumes, greens, oranges, banana, watermelon, dry fruits, cantaloupe, avocado