renal diseases and disorders

8/12/2019 Renal Diseases and Disorders

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Renal Diseases and Disorders

I. Structure of KidneysNephron approximately one million in each kidney A. Glomerulus capillaries; Bowmans capsule B. Proximal convoluted tubule major nutrient reabsorptionC. Loop of Henle water and sodium balanceD. Distal tubule acid-base balanceE. Collecting tubules water reabsorption

II. Hormones A. Vasopressin (anti-diuretic hormone or ADH)

1. From the pituitary glands2. Exerts pressor effect; elevates blood pressure3. Acts on the distal and collecting tubules to reabsorb water

B. Renin1. Enzyme secreted by the renal cortex2. Secreted in response to:

a. Decreased sodium intakeb. Sodium lossc. Hypovolemia or decreased fluid volume

3. Acts on angiotensin (protein substrate from the liver) to form angiotensin I & II

C. Angiotensin II active pressor substance1. Increases heart beat2. Retention and reabsorption of Na3. Excretion of K

D. Aldosterone

1. Acts on distal tubule2. Retention and reabsorption of Na3. Excretion of K

E. Erythropoietin stimulates erythropoiesis in the bone marrow*a hormone secreted by the kidney which acts on stem cells of the bone marrow

F. Activation of vitamin D3 to its active metabolite 1,25 dihydroxycholecalciferol1. Under the influence of parathyroid hormone (PTH)2. Absorption of Ca and P for bone mineralization

III. Renal Functions A. Filtration red blood cells and protein remain in the bloodB. Reabsorption 100% glucose and amino acids; 80-85% water, Na, Cl, KC. Secretion additional ions to maintain acid-base balance; hormones that control B.P. blood componentsD. Excretion wastes, urea, excess ketones, excess water

IV. Renal Solute Load solute excreted in 1L urine*mainly measures urea (nitrogen) and electrolytes (Na)


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V. Laboratory Tests in Renal Diseases A. Decreased glomerular filtration rate (GFR), creatinine clearanceB. Elevated serum creatinine, BUN

*The manifestations of renal disease are direct consequences of the portions of the urinary tract system that is mostaffected. These manifestations include:

1. Glomerular diseases2. Acute renal failure (ARF)

3. Tubular defects4. End-stage renal disease (ESRD)5. Renal stones

Acute Renal Failure sudden shutdown of renal function following metabolic insult or traumatic injury to normal kidn

Renal failure the inability of kidneys to carry out their many functions such as excretion of more than 200 wasproducts, excess fluid and drugs or poisons; regulation of blood pressure; maintenance of acid-base balance andbone health; and production of the hormone erythropoietin which stimulates red blood cell production

Consequences of Renal Failure:

a. Edema d. Bone diseaseb. Uremia e. metabolic acidosisc. Anemia

I. Characteristics of ARF- Sudden reduction in glomerular filtration rate (GFR) and an alteration in the ability of the kidney to exc

metabolic waste excreted daily

II. Etiology: severe injury as in burns, traumatic shock; infections such a peritonitis; toxic agents; obstruction

III. Categories

A. Prerenal (hypoperfused kidney) reversible; nutrition intervention not requiredB. Postrenal (obstructed kidney) reversible; nutrition intervention not requiredC. Intrinsic renal disease (diseased kidney) damage to glomerular and tubular epithelium

Acute tubular necrosis (ATN) most common form of intrinsic renal diseaseThree phases1. Oliguric2. Diuretic3. Convalescent

IV. Symptoms: uremia, metabolic acidosis, fluid and electrolyte imbalance-often associated with oliguria or anuria, but can occur with normal urine flow

V. Nutritional Care Aim: to reduce the accumulation of uremic toxins, control electrolyte abnormalities, and correct fluid retentmaintain nutritional status with or without dialysis treatment


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Diet1. Protein (0.5g/kg BW, high biologic value); increase as GFR returns to normal; should not be severely

restricted with temporary dialysisFor children: protein should never be restricted below 1.0-2.0g/kg BW of high biologic value

2. Kilocalories high35-45 kcal/kg minimum50-60 kcal/kg maximum to attain nitrogen balance

For children: 1.5-2 times normal energy expenditure3. Sodium: 3 g or vary according to fluid retention and hydration status4. Potassium: 30-50 mEq/day5. Phosphorus: depends on frequency of dialysis treatment6. Replace fluid output plus 500 ml

Chronic Renal Failure (CRF) or Chronic Kidney Disease (CKD) this results from the progressive deterioration ofkidneys over a period of months or years, with permanent impairment of renal functions

I. Etiologya. Glomerulonephritis and other renal vascular and tubular disease

b. Diabetes mellitusc. Exposure to toxic substancesd. Infections, venereal diseasee. Congenital abnormalities of both kidneys

II. Symptoms: anorexia, weakness, weight loss, nausea, vomiting, anemia, uremia, malnutrition

III. Nutritional Care Aim: to meet nutritional requirements, minimize uremic complications, maintain acceptable blood chemistrblood pressure, and fluid status

Diet1. Energy for CRF without dialysisa. Adults below 60 years of age: 35 kcal/kg DBW to meet requirementsb. Adults above 60 years: 30-35 kcal/kg DBWc. Underweight patient: 40-45 kcal/kg DBWd. Obese patient: 20-30 kcal/kg DBW

2. No added salt or 2-3 g Na with edema3. Protein restricted when GFR falls

GFR Grams protein/kg/day15-20


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Chronic Renal Insufficiency partial or mild kidney failure characterized by less than normal urine excretionLaboratory findings indicative of early renal damage:a. Hypoalbuminemia c. a decrease of glomerular filtration rateb. Albuminuria

Nutrition care Aim: to slow the progression of kidney disease and possibly delay the need for maintenance dialysis

Diet (Predialysis diet)1. Protein restricted: 0.6-0.6g/kg IBW, high biologic value depending on creatinine clearance to help preserve

residual renal function2. Phosphorus restricted: 5-10mg/kg IBW to help retard progression of renal disease3. Energy

a. Normal weight: 35 kcal/kg IBWb. Underweight/catabolic: 45 kcal/kg IBWc. Obese: 20-30 kcal/kg BDW*adequate kilocalories to maintain somatic and visceral protein stores and body weight

4. Fat: >30% of total kilocalories; PUFA; primary energy source5. Sodium restricted: 1000-3000 mg

6. Potassium not restricted unless serum K is elevated and urine output


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Nephrotic Syndrome (NS) or Nephrosis*a group of symptoms characterized by marked proteinuria, hypoalbuminemia, edema, and hyperlipidemia*characterized by inflammation of the capillary loops of the glomerulus*the primary manifestation of these diseases is hematuria (blood in the urine) due to the capillary inflammationdamages the glomerular barrier to blood cells*presence of hypertension and mild loss of renal function

I. Etiology-progressive glomerulonephritis; associated with diabetes, connective tissue disorder or collagen disease, drreactions from exposure to heavy metals; allergic reaction to bee sting

II. Characteristics1. Massive edema ascites, pedal edema, striae (stretch marks) on the skin of the extremities2. Massive proteinuria as much as 30 g protein/24 hours lost in the urine3. Hypoalbuminemia due to excretion of albumin4. Elevated serum lipids cholesterol >300mg/dL5. Hematuria and anemia due to RBS and iron losses6. Sodium retention7. Fatty liver as a result of malnutrition

8. Loss of appetite or anorexia9. Vitamin D deficiency

III. Nutritional Care Aim: to control the major symptoms of edema and malnutrition that result from the massive protein loss

Diet1. Protein: 0.6 g/kg/day; 80% from high biologic value and 1 gm protein to counteract nitrogen deficit

replace losses2. Kilocalories: high (35-50 kcal/kg) to promote positive nitrogen balance; tissue synthesis3. Sodium: restricted (1-3 g) to reduce edema; to help initiate dialysis

4. Iron and vitamin supplements may be helpful5. Fluid intake: balance with your fluid output; if less than 1L/day6. Cholesterol (


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III. Treatmenta. Urine examination, chemical analysisb. Change urine pH to increase acidity or alkalinity, depending on stone composition

*an acid-ash diet can increase the acidity of the urine and inhibit bacterial growth

IV. Diet*high fluid to dilute urine; prevent formation of stones

Renal Calculi (Kidney Stones)*Kidney stones form when stone constituents become concentrated in the urine and form crystals that grow*Urolithiasis formation of urinary calculi or insoluble constituents in the urine that precipitate as stones in the

urinary passages*excessive intakes of sodium, calciu, oxalates, and protein tend to increase the risk for stone formation

Composition of stonesa. Calcium stones characterized by excretion of normal or excessive (hypercalciuria) amounts of

calcium in the urineb. Uric acid stones this is often associated with gout; uric acid stones form when the urine is persisten

acid and/or contains excessive uric acid

c. Cystine stones this is a consequence of cystinuria (an inhibited disorder of amino acid metabolisminability to metabolize the amino acid cysteine

d. Magnesium stones this is associated with recurring urinary tract infections; stones of magnesiumammonium phosphate (struvite) are formed

Urinary risk factors for stone developmentIncreased Risk Decreased RiskLow urine volumeOxalateUric acidSodium

Acid pHStasisCalcium

High urine volume and flowCitrateGlycoproteinsMagnesium

Dietary factors associated with risk of calcium stonesIncreased Risk Decreased Risk Animal proteinOxalateSodium

CalciumPotassiumMagnesiumFluid intakeFiber

Vitamin B6

I. Factors leading to calculi formationa. Hyperfunction of the parathyroid glandb. Vitamin A deficiencyc. Systemic infectionsd. Inadequate fluid intakee. Metabolic distrubancesf. Prolonged bed restg. Obstruction in the renal flow, producing stasis of the urineh. Excessive vitamin C intake can result in oxalate stone formation


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II. Treatmenta. Liberal fluid intake to dilute the urine and prevent concentration of stone-forming substances

-ensure a minimum urine output (about 2L/day for women; 2.5L/day for men) by consuming 3L of fluidb. Control urine for acidity or alkalinity based on stone type

III. Types of Stones and Diet1. Calcium stones: calcium oxalate, calcium phosphate

Diet: Low calcium (400mg), low oxalate (40-50mg/day)

Limit calcium sources if stones are caused by excess calcium: omit milk, cheese, sardines, shellfishcalcium-rich vegetables

Limit oxalate sources: fruits (berries, grapes, figs, rhubarb, tangerines); (beans, beets, celery, greensokra, spinach, peepers, sweet potatoes, tomatoes); beverages (cocoa, tea, beer); nuts (almonds,cashews, peanuts, nut butters); and grains ( (wheat germ, soy products including tofu, grits)

2. Uric acid stonesDiet: Low purine; alkaline-ash vegetable, milk, fruits

3. Cystine stonesDiet: Low methionine omit milk, eggs, fish and cheese; strictly limit meat; alkaline-ash

Hemodialysis the removal of toxic materials from metabolism from the blood and body fluids by mechanical means; an artificial kidney and extracorporeal dialysis method

I. Characteristics A. Minimal protein losses into the dialysateB. Loss of amino acids 5 to 8 g/dayC. Loss of water-soluble vitamins

II. Nutritional Care Aim:

A. To provide sufficient protein to replace amino acids and nitrogen lost during dialysis, to maintain nitrogbalance, and to prevent excessive accumulation of waste productsB. Provide adequate kilocalories to prevent weight lossC. Limit Na, K, P and fluids

Diet dietary recommendations are based on the frequency of dialysis, renal function, and size of the patient1. Protein 1-1.2g/kg BW, adjusted according to dialysis treatment2. Kilocalories: adequate to maintain weight, mostly supplied by non-protein kcals from fats, oils, and simple 3. Sodium: 60-120 mEq to control HPN and edema4. Potassium: 60-70 mEq to control hyperkalemia5. Fluid limited to an amount equal to urine output plus 1000mL (sources include beverages and foods that are

liquid at room temperature, water content of non-liquid foods, water from oxidation of food)6. Phosphorus: restricted to prevent hyperphosphatemia; use of calcium carbonate or calcium acteate (taken wmeals) as phosphate binders

7. Calcium supplements if with hypocalcemia8. Cholesterol- and fat-controlled, preferably MUFA and PUFA to control hypercholesterolemia and/or

hypertriglyceridemia

III. Supplementary Management A. Intradialytic Parenteral Nutrition (IDPN) for continued weight loss and decline in albumin levelsB. Human recombinant erythropoietin (EPO) a drug recently introduced for the treatment of anemia in ESR


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Peritoneal Dialysis the removal of toxic materials from metabolism from the blood and body fluids by mechanical meand uses the peritoneal membrane

I. Characteristics1. Protein losses (9g/day)2. Loss of amino acids (2-4 g/day)3. Loss of water-soluble vitamins

II. Types1. Continuous Ambulatory Peritoneal Dialysis (CAPD)

a. Self-dialysis technique: machine not requiredb. Patient performs exchanges of dialysate into the peritoneal cavity 4 to 5 timesc. Advantage: mobility; liberalized diet; increased sense of well-beingd. Disadvantage: risk of peritonitis with hospitalization

2. Continuous Cyclic Peritoneal Dialysis (CCPD)a. Home dialysis technique; requires an automated machine to maintain nitrogen balanceb. Patient performs five to six 2L exchanges (1.5 hours duration) at night; one 1L exchangec. Advantage: less risk of peritonitis

III. Nutritional Care1. Provide sufficient protein to replace large losses in the dialysate and to maintain nitrogen balance2. Prevent excessive weight gain3. Control hyperlipidemia, hypertension, edema, hyperphosphatemia, and renal osteodystrophy

Diet1. Protein: 1.2-1.5g/kg BW to replace losses, maintain nitrogen balance2. Kilocalories computed as:

a. Dietary kcal = TER kcal from dialysateb. Kcal from dialysate = Glucose concenteration (g/L) x 3.7 kcal/g x 0.8 x volume (L)

3. Sodium: 90-120mEq for CAPD; not restricted in CCPD4. Potassium: 60-70mEq if serum P is elevated; not restricted in CCPD5. Calcium supplement as needed6. Simple CHO restricted if with hypertriglyceridemia and overweight7. Cholesterol and saturated fat low if with hypercholesterolemia8. Fluid restriction not necessary; up to 2L may be tolerated

renal diseases and disorders

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