Nutrition Renal Disease (13)

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mse263
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253125
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Nutrition Renal Disease (13)
Updated:
2013-12-14 13:02:08
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Nutrition
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MBS,Nutrition
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Final Exam
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  1. Functions of the Kidney
    • helps maintain fluid balance in the body by removing excess sodium & fluid
    • eliminates waste (urea, drug metabolites, etc)
    • maintains acid-base balance through production & excretion of hydrogen & bicarbonate
    • produces hormones
  2. How does the kidney regulate the volume & composition of fluid in the body?
    by altering the osmolality, or concentration of sodium particles, of the fluid passing through the filtering system
  3. What happens if the body has a low plasma volume (dehydrated)?
    • low plasma volume results in decreased afferent arterial blood pressure & increased activity of the renal sympathetic nerves
    • these events stimulate juxta. renal granular cells to secrete RENIN
    • renin converts angiotensinogen into angiotensin I
    • angiotensin I is cleaved in the lungs by ACE into angiotensin II
    • angiotensin II stimulates the adrenal cortex to release aldosterone
    • aldosterone increases reabsorption of ions & water at the distal tubules & collecting ducts of the nephron
    • result: increased water & sodium retention
  4. What happens if a person has ingested excess water (overhydration)?
    • excess water results in decreased body-fluid osmolarity & an increased concentration of H2O
    • these events stimulate osmoreceptors in the hypothalamus (brain gets involved)
    • which activate the posterior pituitary to decrease production of ADH (WANT to diurese)
    • less ADH means less water reabsorption by the collecting ducts
    • result: increased water excretion
  5. Acid-Base Balance of the Kidney
    • Bicarbonate is reabsorbed in the proximal tubule w/ sodium
    • *common for patients with CKD (malfunctioning proximal tubule) to have acidosis due to low bicarbonate levels (inability to reabsorb)
    • this common acidosis with CKD can facilitate PROTEIN BREAKDOWN
    • Hydrogen secretion in the collecting duct
  6. Erythropoietin (EPO)
    • stimulates RBC production in the bone marrow
    • EPO deficiency can be seen as a result of kidney disease & is the underlying cause of severe anemia commonly seen in conjunction with renal failure
  7. Vitamin D
    • enzyme found in the kidney converts a vitamin D precursor into its active form
    • 1,25-dihydroxy-vitamin D3 stimulates intestinal Ca2+ & PO43- absorption
    • in ESRD (CKD) vitamin D is NOT converted
    • ↓ active vitamin D leads to ↑ PTH → ↑Ca2+ resorption from bone
  8. Secondary Hyperparathyroidism
    • excessive secretion of PTH in response to hypocalcemia (low blood calcium levels) & associated hypertrophy of the glands OFTEN seen in renal disease
    • a malfunctioning kidney can't convert vitamin D to its active form, resulting in low blood calcium levels
    • blood calcium is important for proper nerve & muscle function
    • low blood calcium levels stimulates the release of PTH to draw on bone Ca2+ stores to rejuvenate & maintain appropriate blood Ca2+ levels
  9. Why do people with end-stage kidney disease (stage 5) often have elevated phosphorous levels?
    • because unhealthy kidneys are no longer able to remove phosphorus from the blood & filter any excess in urine for excretion
    • when PTH breaks down bone to liberate Ca2+ & replenish its blood levels, free phosphorous may bind to the Ca2+ (they're highly attracted to each other), preventing Ca2+ blood levels from returning to normal
    • this only worsens secondary hyperparathyroidism
  10. Chronic Kidney Disease (CKD)
    • kidney damage for or over 3 months which causes structural or functional abnormalities (possibly with decreased GFR)
    • manifestations include either pathological damage OR blood or urine markers of kidney damage
    • can also be detected via imaging



    *it's not unusual for people in the early stages of the disease to NOT KNOW they have CKD

    CKD becomes more prevalent in older individuals
  11. What are a person's options at Stage 5 CKD after kidney failure?
    • kidney transplant or dialysis is required
    • dialysis is MORE common than transplant for treatment
    • most transplants don't last a lifetime (5-15 years); not unusual for a patient on dialysis to have HAD a transplant
    • there are different type of dialysis: hemodialysis (HD), peritoneal dialysis (PD), or continuous renal replacement therapy (CRRT)
  12. continuous renal replacement therapy (CRRT)
    designed for acutely ill patients in the hospital
  13. What are the 3 main components of treating kidney disease?
    • 1. delay its progression
    • 2. treat any complications: to prevent illness/symptoms
    • 3. RRT: Renal Replacement Therapy
  14. What CAUSES renal failure?
    • 1. primarily metabolic diseases that involve the kidneys (eg. DM or lupus)
    • 2. hypertension → nephroschlerosis → damage to the renal blood vessels
    • 3. disease of the glomeruli causing glomerulonephritis
    • 4. obstructive diseases (eg. kidney stones or polycystic kidney disease)

    • Diabetes - 45%
    • Hypertension and RAS - 27%
    • Other/unknown – 10%
    • Glomerular Diseases - 8%
    • Interstitial Diseases - 4%
    • Cystic Diseases (PKD) - 3%
    • Lupus - 2%
    • Other glomerulonephritis - 2%
  15. What would a dietician's overarching goals be for a person with kidney disease?
    • 1. assist nutritionally in the preservation of renal function
    • 2. assist in control of uremic symptoms
    • 3. ensure nutritional adequacy & preservation of lean body mass
  16. Causes of Malnutrition in CKD Patients
    • unpalatable or inadequate diets
    • delayed gastric emptying (vomiting is often a problem)
    • taste changes
    • inflammation, infection, sepsis (often hospitalized)
    • endocrine disorders of uremia (insulin resistance, hyperparathyroidism)
    • medications
    • underlying illness or hospitalization
    • loneliness, depression, ignorance, poverty
    • metabolic acidosis (can lead to protein breakdown, will contribute to malnutrition)
  17. What are the biochemical markers important to measure when assessing a persons GFR?
    • albumin*
    • urea
    • creatinine
    • potassium
    • phosphate
    • as the disease progresses ALL of these will INCREASE
  18. Albumin & CKD
    • in this population, INCREASED albumin levels are HIGHLY associated with mortality
    • however a confounding factor is albumin's linked to hydration status: as fluid levels, increase → albumin levels decrease
    • a patient with kidney disease could easily have edema, therefore lowered albumin levels that wouldn't be indicative of their disease state
  19. What type of diet is a person with CKD Stages 3-4 on?
    • Protein: .6 - .75 g/kg of SBW & > 50% HBV (high biological value) protein
    • Energy: 35 cal/kg SBW (<60 y/o, is higher), 30-35 kcal/kg SBW (>60 y/o, is lower)
    • Na+: varies from 1-3 g to NAS (no added salt diets)
    • Fluid: unrestricted UNLESS someone's peeing less
    • K+: Usually unrestricted unless serum level is high
    • Calcium 1000-1500mg/d
    • Phosphorus 800 mg/d
  20. Protein Intake w/ CKD
    • diet should be protein controlled
    • 0.6-0.8 g/kg is recommended for patients with CKD if they are NOT on dialysis
    • *protein restricted diets can slow GFR decline & maintain stable nutrition status in non-diabetic patients with CKD
    • *difficult to restrict protein in diabetics w/ CKD b/c it might be better for THEM to eat protein over carbs & fats
    • also don't want to restrict protein in someone who's malnourished - this applied to people on normal diets without serious conflicting factors
  21. Uremia
    urea & other waste products normally excreted into the urine are retained in the blood
  22. How should a patient's diet who is NOT eating because of uremia be modified?
    • their protein intake should be LESS restricted - they should eat more protein
    • restriction of protein isn't necessary because they need more nutrients & in this condition they're ALREADY not eating enough protein already (by not eating…)
  23. Sodium & CKD
    • the kidneys can't maintain proper fluid & sodium levels w/ renal failure
    • this leads to abnormal sodium & water RETENTION
    • extra sodium in the body further increases fluid reabsorption, leading to edema, hypertension, dyspnea (shortness of breath), & stress on the heart
    • easy to teach but hard to follow a low sodium diet
  24. Dry Weight
    • the weight at which all or most excess body fluid will have been removed & a patient is normotensive (neither hyper or hypotensive)
    • this is the weight used to make decision about what and how much therapy to use (eg. diuretics, ultrafiltration, dietary [low fluid/sodium] modifications)
  25. Potassium Regulation & CKD
    • failing kidneys have a reduced capability to excrete K+ → hyperkalemia, a life-threatening condition that affects heart rhythm & pumping ability
    • *an URGENT reason a person might need treatment
    • if a patients serum K+ levels are increasing their potassium should be restricted
    • high K+ levels can lead to cardiac arrhythmia
  26. Phosphorus Regulation & CKD
    • higher levels of serum phosphorus are seen with a lower GFR
    • hyperphosphatemia develops when the GFR falls below 25 ml/min
    • hyperphosphatemia can cause soft tissue (joints, muscles, blood vessels) calcification & secondary hyperparathyroidism
    • free phosphorus will bind to serum calcium, deposit, & develop calcifications under the skin because the body can't process phosphorus-calcium complexes
  27. How can hyperphosphatemia be prevented?
    • by making sure a person gets adequate calcium (to stem efflux from the bones) & limiting phosphorous to 800 mg/day
    • limiting high protein foods, nuts/legumes, diary products, whole grains, & cola drinks, all of which are high in phosphorous
    • is also used as an additive in some drinks (tropicana, hawaiian punch)
  28. Phosphate Binders
    • a group of meds used to reduce the absorption of phosphate and therefore treat hyperphosphatemia in CKD patients
    • they're taken with food
    • Al based binders were used in 80’s but are associated w/ osteomalacia, adynamic bone disease, myopathy, & dementia
    • Ca2+ based binders are currently used but are associated w/ hypercalcemia
  29. Anemia of Renal Disease
    • in renal disease, the decrease in production of erthropoeitin causes the majority of patients to develop normocytic or normochromic anemia (too few RBCs)
    • normochromic anemia leads to impaired tissue oxygen delivery, lethargy, congestive heart failure, angina, impaired cognition, & worsening of dyspnea if already present
  30. How are normocytic & normochromic anemia treated?
    • 1. Epogen (recombinant human erythropoeitin), a synthetic form of erythropoietin
    • during HD or IM
    • 2. iron supplementation: erythropoeisis requires an adequate iron supply
    • increased hematocrit brings about better appetite and intake
  31. Lipid Disorders & CKD
    • with renal dysfunction there is a derangement of lipid metabolism including increased TAGs, decreased HDL, but increased total cholesterol
    • cardiovascular disease is often seen in these patients & increases morbidity & mortality in CKD patients
    • need to maximize the polyunsaturated to saturated fat ratio
  32. IN TOTAL what monitor in a person with renal disease
    • 1) their dietary intake: look for uremia, appetite changes, nausea, vomiting
    • 2) anthropometry: weight changes, skinfolds, muscle circumference
    • 3) biochemical levels: albumin*, creatinine, urea, phosphate, potassium
    • to NOTE disease progression
  33. What GFR corresponds to CKD Stage 5, & therefore kidney transplant or dialysis?
    a GFR less that 15
  34. Hemodialysis (HD)
    • removes large volumes of blood, filters out the toxins, then returns it 3x a week
    • is a time consuming and exhaustive process
    • there is a large potential for hemodynamic instability - hypotension is common in this procedure, as is cardiovascular instability, nausea, vomiting, post HD fatigue, & protein losses of about 6-8g per treatment
    • *patients need to eat more protein once the therapy begins if they were previously protein restricted
  35. What are some counterintuitive dietary changes for a person receiving hemodialysis?
    • fiber is added/important (constipation is a problem in this population)
    • Ca2+ should be monitored more closely, especially if phosbinders are being used
    • renal vitamin supplement is recommended (B vitamins are especially important)
    • fluid = urine output + 1 Liter
    • intuitive: protein decreases (should be mostly HBV), energy is exactly the SAME, and sodium, potassium, & phosphorous all decrease
  36. Peritoneal Dialysis (PD)
    • dialysate (fluid) sits within the abdomen & the peritonium acts as a filter; the dialysate is eventually excreted into a drain bag
    • happens on a daily basis or multiple times a day usually at home
    • CAPD: continuous ambulatory
    • CCPD: continuous cyclic
  37. What are the side-effects of peritoneal dialysis?
    • Abdominal discomfort
    • Glucose Absorption: b/c fluid has dextrose, some of dialysate gets absorbed & increases satiety
    • Peritonitis: inflammation of the peritoneum due to its constant use
    • Protein losses of 8-10 g/day (MORE than with hemodialysis)
  38. What are some counterintuitive dietary changes for a person receiving peritoneal Dialysis?
    • protein is increased: difficult to manage b/c of satiety that comes along with the glucose fluid
    • more LIBERAL diet (more fluid, Na+, K+)
    • same thing about fiber & Ca2+
  39. Why do nutritionist WANT nutritional biochem markers such as BUN & creatinine to be high in dialysis patients?
    • because that's indicative of their TRUE renal function
    • if they're lower, patients aren't eating adequate protein
    • Serum BUN (Blood Urea Nitrogen), Serum & Creatinine SHOULD REMAIN ELEVATED IN DIALYSIS PATIENTS
  40. Which can dialysis remove from the blood, phosphorous or potassium?
    • POTASSIUM
    • phosphorous is not well filtered by dialysis machines
    • blood levels of these molecules are checked to make sure they're not too high
    • high levels can cause cardiac or bone issues
  41. Compare & Contrast

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