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Chapter 21Kidney DiseaseChapter 21Lesson 21.1Key ConceptsKidney disease interferes with the normal capacity of nephrons to filter waste products of body metabolism. Key Concepts, cont’dShort-term kidney disease requires basic nutrition support for healing rather than dietary restriction.Kidney Disease3.8 million Americans have some form of kidney disease.42,000 persons die from such diseases each year.Kidney Disease, cont’dDual Role of the KidneysKidneys make urine, through which they excrete most of the waste products of metabolism.Kidneys control the concentrations of most constituents of body fluids, especially blood.Basic Structure and FunctionStructuresBasic unit is the nephronGlomerulusTubulesFunctionExcretory and regulatoryEndocrineBasic StructureRenal NephronsBasic functional unit of the kidneyMajor nephron functionsFiltration of materials in bloodReabsorption of needed substancesSecretion of hydrogen ions to maintain acid-base balanceExcretion of waste materialsAdditional functionsRenin secretion (for body water balance)Erythropoietin secretion (for red cell production)Vitamin D activationNephron StructuresGlomerulusCluster of branching capillariesCup-shaped membrane at the head of each nephron forms the Bowman’s capsuleFilters waste products from bloodGlomerular filtration rate: Preferred method of monitoring kidney functionTubulesProximal tubuleLoop of HenleDistal tubuleCollecting tubuleTubulesCauses of Kidney DiseaseInfection and obstructionDamage from other diseasesToxinsGenetic defectRisk factorsCauses of Kidney Disease, cont’dRisk Factors and Causes of Kidney DiseaseSociodemographic factorsOlder ageRacial or ethnic minority statusExposure to certain chemical and environmental conditionsLow income or educationRisk Factors and Causes of Kidney Disease, cont’dClinical factorsPoor glycemic control in diabetesHypertensionAutoimmune diseaseSystemic infectionsUrinary tract infectionsUrinary stonesRisk Factors and Causes of Kidney Disease, cont’dClinical factorsLower urinary tract obstructionNeoplasiaFamily history of chronic kidney diseaseRecovery from acute kidney failureReduction in kidney massExposure to certain nephrotoxic drugsLow birth weightFrom Eknoyan G, Levin NW: K/DOQI clinical practice guidelines for chronic kidneydisease: evaluation, classification, and stratification, Am J Kidney Dis 39(2 suppl):1; 2002.Copyright National Kidney Foundation. Medical Nutrition TherapyBased on the nature of the disease process and individual responsesLength of diseaseLong term: More specific nutrient modificationsDegree of impaired renal functionExtensive: Extensive nutrition therapy requiredIndividual clinical symptomsAcute Glomerulonephritis or Nephritic SyndromeClinical symptoms: Hematuria, proteinurea, edema, mild hypertension, depressed appetite, possible oliguria or anuriaAcute Glomerulonephritis or Nephritic Syndrome, cont’dMedical Nutrition TherapyAcute glomerulonephritisUncomplicated disease: Antibiotics and bed restAdvanced disease: Possible restriction of protein, sodiumLiberal intake of carbohydratesPotassium intake may be monitoredFluid intake may be restrictedNephrotic SyndromeClinical symptoms: Massive edema, ascites, proteinurea, distended abdomen, reduced plasma protein level, body tissue wastingMedical Nutrition TherapyNephrotic syndromeProtein intake to meet nutrition/growth needs (without excess)CarbohydrateLipidsSodium (~3 g/day)PotassiumWaterOther minerals and vitaminsChapter 21Lesson 21.2Key ConceptsThe progressive degeneration of chronic renal failure requires dialysis treatment and modification according to individual disease status. Key Concepts, cont’dCurrent therapy for renal stones depends more on basic nutrition and health support for medical treatment than on major food and nutrient restrictions.Kidney Disease3.8 million Americans have some form of kidney disease.42,000 persons die from such diseases each year.Acute Kidney FailurePrerenalIntrinsicPostrenal obstructionAcute Renal FailureClinical symptoms: Oliguria, proteinurea, hematuria, loss of appetite, nausea/vomiting, fatigue, edema, itchy skinShort-term dialysis may be neededMay progress to chronic renal failureMedical Nutrition TherapyAcute kidney failureGoal is to improve or maintain nutritional statusParenteral nutrition therapy may be requiredRecommendations for protein intake have been debatedIndividualized therapy based on renal function (indicated by glomerular filtration rate)Medical Nutrition TherapyChronic Kidney FailureCaused by progressive breakdown of renal tissue, which impairs all renal functionsDevelops slowlyNo cure (other than kidney transplant)Clinical symptoms: Polyuria/oliguria/anuria, electrolyte imbalances, nitrogen retention, anemia, hypertension, azotemia, weakness, shortness of breath, fatigue, thirst, appetite loss, bleeding, muscular twitchingMedical Nutrition Therapy ObjectivesReduce protein breakdownAvoid dehydration or excess hydrationCorrect acidosisCorrect electrolyte imbalancesControl fluid and electrolyte lossesMaintain optimal nutritional statusMaintain appetite and moraleControl complications of hypertension, bone pain, nervous system involvementSlow rate of renal failureMedical Nutrition Therapy PrinciplesProvide enough protein therapy to maintain tissue integrity while avoiding excessProvide amino acid supplements for protein supplementationReserve protein for tissue synthesis by ensuring adequate carbohydrates and fatsMaintain adequate urine volume with water(Possibly) restrict sodium, phosphate, calciumSupplement diet with multivitaminStages of Chronic Kidney DiseaseEnd-Stage Kidney DiseaseOccurs when patient’s glomerular filtration rate decreases to 15 ml/minIrreversible damage to most nephronsDialysis or transplant are only optionsHemodialysisUses an artificial kidney machine to remove toxic substances from blood, restore nutrients and metabolitesTwo to three treatments per week typically requiredPatient’s blood makes several “round trips” through machineDialysis solution (dialysate) removes excess waste materialHemodialysis, cont’dHemodialysis, cont’dHemodialysis PatientMedical nutrition therapyMaintain protein and energy balancePrevent dehydration or fluid overloadMaintain normal serum potassium and sodium levelsMaintain acceptable phosphate and calcium levelsHemodialysis Patient, cont’dOther dietary concernsAvoid protein energy malnutrition by careful calculation of protein allowanceMaintain body mass index of 25 to 28 kg/m2 Fluid intake: 1000 ml/day, plus amount equal to urine outputSodium: 2000 mg/dayPotassium: 2000-3000 mg/daySupplement of water-soluble vitamins (e.g., B complex, C)Peritoneal DialysisPerformed at homePatient introduces dialysate solution directly into peritoneal cavity four to five times per daySurgical insertion of permanent catheter is requiredDisposable bag containing dialysate solution is attached to catheterDiet is more liberal than with hemodialysisPeritoneal Dialysis, cont’dPeritoneal Dialysis, cont’dPeritoneal Dialysis, cont’dMedical nutrition therapyIncrease protein intake to 1.2 to 1.5 g/kg body weightIncrease potassium with a wide variety of fruits and vegetablesEncourage liberal fluid intake of 1500 to 2000 ml/dayAvoid sweets and fatsMaintain lean body weightComorbid ConditionsOsteodystrophyBone disease resulting from defective bone formationFound in about 40% of patients with decreased kidney function and 100% of patients with kidney failureNeuropathyCentral and peripheral neurologic disordersFound in up to 65% of patients at the initiation of dialysisKidney StonesBasic cause is unknownFactors relating to urine or urinary tract environment contribute to formationPresent in 5% of U.S. women and 12% of U.S. menMajor stones are formed from one of three substances:CalciumStruviteUric acidKidney Stones, cont’dRisk FactorsCalcium Stones70% to 80% of kidney stones are composed of calcium oxalateAlmost half result from genetic predispositionOther causesExcess calcium in blood (hypercalcemia) or urine (hypercalciuria)Excess oxalate in urine (hyperoxaluria)Low levels of citrate in urine (hypocitraturia)InfectionExamples of Food Sources of OxalatesFruits: Berries, Concord grapes, currants, figs, fruit cocktail, plums, rhubarb, tangerinesVegetables: Baked/green/wax beans, beet/collard greens, beets, celery, Swiss chard, chives, eggplant, endive, kale, okra, green peppers, spinach, sweet potatoes, tomatoesNuts: Almonds, cashews, peanuts/peanut butter Beverages: Cocoa, draft beer, teaOther: Grits, tofu, wheat germStruvite StonesComposed of magnesium ammonium phosphateMainly caused by urinary tract infections rather than specific nutrientNo diet therapy is involvedUsually removed surgicallyOther StonesCystine stonesCaused by genetic metabolic defectOccur rarelyXanthine stonesAssociated with treatment for gout and family history of goutOccur rarelyKidney Stones: Symptoms and TreatmentClinical symptoms: Severe pain, other urinary symptoms, general weakness, feverSeveral considerations for treatmentFluid intake to prevent accumulation of materialsDietary control of stone constituentsAchievement of desired pH of urine with medicationUse of binding agents to prevent absorption of stone elementsDrug therapy in combination with diet therapyNutrition Therapy: Calcium StonesLow-calcium diet (~400 mg/day) recommended for those with supersaturation of calcium in the urine and who are not at risk for bone lossIf stone is calcium phosphate, sources of phosphorus (e.g., meats, legumes, nuts) are controlledFluid intake increasedSodium intake decreasedFiber foods high in phytates increasedNutrition Therapy: Uric Acid StonesLow-purine diet sometimes recommendedAvoid:Organ meatsAlcoholAnchovies, sardinesYeastLegumes, mushrooms, spinach, asparagus, cauliflowerPoultryMedical Nutrition Therapy: Cystine StonesLow-methionine diet (essentially a low-protein diet) sometimes recommendedIn children, a regular diet to support growth is recommendedMedical drug therapy is used to control infection or produce more alkaline urineGeneral Dietary Principles: Kidney StonesSummaryThe nephrons are the functional units of the kidneys. Through these unique structures the kidney maintains life-sustaining blood levels of materials required for life and health. The nephrons accomplish their tremendous task by constantly “laundering” the blood many times each day, returning necessary elements to the blood and eliminating the remainder in concentrated urine.Summary, cont’dVarious diseases that interfere with the vital function of nephrons can cause kidney disease.At its end stage, chronic kidney disease is treated by dialysis or kidney transplantation. Dialysis patients require close monitoring for protein, water, and electrolyte balance. Summary, cont’dKidney diseases have predisposing factors (e.g., recurrent urinary tract infections may lead to renal calculi, and progressive glomerulonephritis may lead to chronic nephrotic syndrome and kidney failure). Kidney stones may be formed from a variety of substances. For some patient, a change in dietary intake of the identified substance (e.g. fluid, sodium, oxalate, purine) may decrease stone formation. ................
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