Renal Disease

Kidney Function: to maintain normal composition and volume of the blood

Anatomy of Kidney

❧1 million Nephrons: Consists of● Glomerulus connected to a series of tubules

which can be broken into functional segments• proximal convoluted tubule• loop of Henle• distal tubule• collecting duct

● Glomerulus surrounded by Bowman’s capsule• mass of capillaries: blood is filtered to produce

ultrafiltrate

Kidney Function

❧Ultrafiltrate contains blood material that is less than 6500 molecular weight

❧No blood cells❧No protein❧No other large molecules

Kidney Function

❧Water and electrolyte conservation● Antidiuretic Hormone (ADH) secreted by

posterior pituitary when osmolality of blood rises

• Shuts off when osmolality falls● Kidney can concentrate urine as much as 1200

mOsm or as dilute as 50 mOsm● Urinary volumes vary based on need to excrete

extra fluid

Kidney Function

❧ADH: Diseased kidney doesn’t respond to ADH as well and tends to allow water retention

● Reduced urine output in Renal patients● oliguria: less than 500 ml/day

Kidney Function

❧Other Waste Products accumulate with renal failure

❧Azotemia: Build up of urea, uric acid, creatinine and ammonia

Kidney Function: Blood Pressure

❧Renin-Angiotensin System:● Decreased blood pressure induces glomerular

cells to secrete renin• Acts in plasma to form angiotensin I• converted to angiotensin II

– vasoconstrictor: elevates BP– stimulates aldosterone secretion by adrenal glands

» Causes kidneys to retain water and sodium

● In diseased kidney, this mecahism may be less functional: high or low blood pressure/water retention

Kidney Function: RBC Formation

❧Erythropoietin: kidney produces this hormone

● Acts on bone marrow to produce RBC’s● In diseased kidney, lack of Erythropoietin:

• results in severe anemia● Renal patients are given injections of

erthyropoietin to stimulate RBC rpduction

Kidney Function: Ca, P

❧Vitamin D activation happens in kidney❧With diseased kidney, this is slowed down❧Less active vitamin D

● Results in less absorption of Ca in gut● more bone release of Ca and weak bones

• Poor bone status

Diseases of the Kidney

❧Glomerular Diseases● Nephrotic syndrome● Nephritic syndrome

❧Tubule and interstitium diseases● Acute renal failure (ARF)● Other tubular diseases● Pyelonephritis

Nephrotic Syndrome

❧Group of diseases cause● Protein loss through glomeruli● hypoalbuminemia with edema

• concentrates blood● hypercholesterolemia● hypercoagulability● abnormal bone metabolism

Nephrotic Syndrome

❧Most often caused by:● Diabetes● systemic lupus eryththematosus(SLE)

• connective tissue disorder of immune origin• causes damage to many systems and noted by skin

eruptions, arthritis, neurological problems● amyloidosis:abnormal deposits of amyloid in

tissues• a starch-like glycoprotein primary cause unknown• secondary due to TB and rheumatoid arthritis

Nephrotic Syndrome: Nut Care

❧Objective: replace lost protein in urine❧High Biological Value Protein from 0.6 to

1.5 g/kg/d❧Energy 35 to 50 kcal/kg/d for adults; 100 to

150 kcal/kd/d for kids● to spare protein

❧Edema: mild sodium restriction❧Hypercholesterolemia: lipid lowering drugs

with chronic Nephrotic Syndrome

Nephritic Syndrome

❧Inflammation of capillary loops of glomerulus caused by several disease states

● acute glomerulonephritides: often caused by streptococcal infection damaging glomerular barrier to blood cells

• Blood in urine• Sudden onset/short duration• May proceed to complete recovery, chronic

nephrotic syndrome, End Stage Renal Disease(ESRD)

Nephritic Syndrome: Nut Care

❧Objectives: maintain good nutritional status❧Often focus is on treating underlying cause❧Usually no need to restrict protein, or K

unless uremia or hyperkalemia exists❧Sodium restriction with HTN

Diseases of Tubules & Interstitium

❧Acute Renal Failure: Sudden reduction in Glomerular Filtration Rate (GFR)

❧GFR: the quantity of glomerular filtrate formed per unit of time by the kidneys

❧Results in the inability to filter wastes from the blood

❧Causes are many

ARF : Causes 3 Categories

❧Prerenal❧Intrinsic❧Postrenal Obstructive❧Treatment: remove underlying problem❧Course of the problem depends on

underlying cause

ARF: Intrinsic Problems

❧Possible causes:● toxic drugs● allergy to drugs● progressive glomerulonephritis● ischemia leading to acute tubular necrosis

• infections, severe trauma, surgical accidents• mortality about 70 %• treated with hemodialysis to reduce acidosis• Diuretic phase then return of waste elmination

ARF: Nut Care

❧Early: TPN may be used to maintain nutritional status

❧Hemodialysis, peritoneal dialysis or continuous arteriovenous filtration (CAVH)

● CAVH uses small ultra filtration membranes to produce an ultrafiltrate

• this is replaced with parenteral nutrition fluids to prevent fluid overload

ARF: Nut Care

❧Protein:Early, TPN with Glucose and some protein in form of essential A.A.s such as Aminosyn-RF(Abbot Labs)

❧Amount of Protein dependent on pt● 0.3 g/kg and progress toward 0.8 to 1 as pt

improves

❧Energy needs are high: 50 kcal/kg most from CHO and lipids via TPN or enterally with addition of formulas (Polycose, Ross)

Pyelonephritis: UTI

❧No specific nutritional management❧Chronic cases: cranberry juice

● Reduced adherence of E.coli to epithelial walls of urinary tract

Nephrolithiasis: Kidney Stones

❧10 % of men and 3 % of women have a stone during adulthood

❧Formed in kidney when substances in urine reach levels that cause crystallization

❧May be made from calcium salts, uric acid, cystine, struvite (ammonium, magnesium, and phosphate)

Kidney Stones: treatment

❧In all cases: High fluid intake (1.5 to 2 liter/day) to keep urine dilute

❧Other intervention depends on the cause❧80% of stones composed of Ca oxalate or

Ca phosphate❧Causes are multiple:

● hyperparathyroid ism, hyperuricosuria, renal tubule acidosis (RTA)

Kidney Stones: Treatment

❧Remove underlying cause:● e.g.: remove parathyroid adenoma if

Hyperparathyroid● Treat RTA with medications to reduce acidity● Hypercalciuria seldom treated with low Ca diet

❧Nutrition: Reduce Oxalate in diet, add additional Ca to diet to tie up oxalate in gut

Kidney Stones: Uric Acid

❧Associated with gout, an acid urine❧Treatment with raising urine pH to 6 to 6.5

through high alkaline-ash diet● milk, nuts, vegetables except corn and lentils,

all fruits except cranberries, prunes, plums, molassess

● avoid breads, meats, cheese, pnut butter, and vegies and fruits above

Glomerular Filtration Rate (GFR)

❧Defn: total plasma volume filtered by the kidney per unit of time

❧Normal is 120 ml/min

❧GFR = Urineinulin X Urine volume

❧ _____________________

❧ Plasmainulin

❧Can also be done with creatinine

Normal Kidney Function

❧How long does it take to filter all of a person’s blood? HINT: 6 L of blood

Other Labs Used to Determine Kidney Function

❧Blood Urea Nitrogen(BUN): How well urea is cleared by the kidney

● Normal is 8 to 23 mg/dl● High is indication of poor fxn

❧Creatinine: end product of creatine metabolism in muscle; cleared in urine

● Normal is 0.6 to 1.6 mg/dl● High is indication of poor function

Progressive Nature of Renal Disease

❧Slow, steady, decline in renal function❧Nutrition intervention depends on Renal

Function determined by GFR❧Protein Intake: major concern❧Protein GFR❧0.8 g/kg(60%HBV) >55 ml/min❧0.6g/kg(60% HBV) 25-55 ml/min

Progressive Renal Disease

❧Protein restriction: individualized● Must be weighed against possible protein

malnutrition● If elected, careful monitoring of protein status

must be made with anthropometric and lab values

End-Stage Renal Disease

❧Can be caused by several disease states❧90 % have Db, glomerulonephritis, or HTN❧Problems include:

● inability to remove wastes● maintenance of fluid and electrolyte balance● problems with hormone production

❧Uremia: high BUN, a major problem

Uremia: Symptoms

❧With BUN at 100 and Creatinine at 10-12 symptoms usually show up

❧Generally: weakness, nausea, cramping, itching, metallic taste

❧Further intervention required

ESRD: Treatment

❧Transplantation❧Dialysis

● Hemo● Peritoneal

• intermittent peritoneal dialysis (IPD)• Continuous ambulatory PD(CAPD)

Transplantation: Nut Care

❧Based on metabolic effects of immunosuppressive meds: corticosteroids and cyclosporine

❧Corticosteroids:● increase PRO metabolism, hyperlipidemia, Na

retention, wt gain, glucose intolerance, reduced Ca and Vit D metabolism

❧Cyclosporine: hyperkalemia, HTN, ^ lipids

Transplant Nutrition Care

❧First month Post-transplant:● PRO: 1.5 to 2 g/kg● Energy: 30 to 35 kcal/kg● moderate Na restriction to prevent fluid

retention (80-100 mEq/d); monitor K and P

❧After one month:● PRO: 1 g/kg● Adjust Kcal to maintain/achieve Ideal weight

Hemodialysis

❧Most common form of dialysis❧Fistula created by surgery connects an

artery and a vein usually on the forearm● may require an artificial vessel to enlarge the

vessel● Large needles are temporarily inserted to allow

blood to exit the body and circulate through the dialysis machine

● Usually required 3 x / week for 3 to 5 hours

Hemodialysis: Nut Care

❧Energy: 35 kcal/kg IBW❧PRO: 1 to 1.2 g/kg; 1.2 to 1.5 if needed❧Fluid: 800 ml/d + urine output❧Na: 2-3 grams/day❧K: 2-3 grams/day❧P: 1 to 1.2 g/d

Peritoneal Dialysis

❧Makes use of the semi permeable membrane of the tissues in the peritoneal cavity

❧Catheter surgically implanted in the abdomen

❧Dextrose containing dialysate is instilled into abdomen

● wastes diffuse into dialysate

Peritoneal Dialysis

❧Fluid is withdrawn and discarded; new fluid is then instilled

❧Less efficient then hemo❧10 to 12 hrs, 3 x week❧PRO: 1.2 to 1.5 g/kg due to larger Pro loss❧Energy: 30 kcal/kg (40-50 for repletion)❧Fluid, Na, K, and P same as hemo

Continuous Ambulatory Peritoneal Dialysis(CAPD)

❧Similar to peritoneal but the dialysate is exchanged manually without the help of a machine

❧Exchanged 4 to 5 x /day for 24-hour treatment

❧Increased loss of Protein, increased absorption of Dextrose, up to 800 kcal/d

CAPD Nut Care

❧PRO: 1.2 to 1.5 g/kg❧Energy: 25 kcal/kg❧Fluid: ad lib❧Na: 6 - 8 grams / d❧K: 3-4 g/d❧P: 1.5 to 3 g/d❧Weight gain is the norm for CAPD patients

ESRD: Other concerns

❧Psychological Support: large life changes● Depression: lack desire to eat● Thirst, lack of taste and taste changes due to

uremia

❧Vitamin D status: activation of Vit D happens in the kidney

● loss of function results in low status● Vit D supplements

Complications

❧Low Vit D results in low Ca in blood● Triggers release of PTH; this removes Ca from

bone● Results in osteitis fibrosa cystica: a

demineralized bone disease causing dull bone pain

● Serum P remains high because it is not cleared by kidney

● Calcium intake should be high, P should be low

Complications of Renal Disease

❧Calcium supplements help bind P in the gut● Ca carbonate, acetate, lactate or gluconate● Ca citrate is avoided because it helps absorb Al

❧Vit D orally or intravenous helps with hypocalcemia

❧Fluoride serum levels often high in dialysis pt: contributes to decalcification of bone

● Deionized Fl containing water before used in dialysis

Iron/Hemoglobin status

❧Kidney produces erythropoietin which induces bone to produce RBCs

● Synthetic EPO injections are used to treat

❧Vitamin deficiencies may occur● Reduced intake with P restriction: many P rich

foods are also vitamin rich, e.g.: fruits and vegetables

● Water soluble vitamins are dialyzed off

Complications

❧Vitamin supplements given: some specially formulated for dialysis pts

● Nephrocaps: Fleming and Co.

❧Carbohydrate: glucose intolerance due to tissue resistance to insulin

● may require control of glucose in diet in hyper● may require addition of dextrose to dialysate in

hypoglycemic

Complications

❧Atherosclerosis: most frequent cause of death in hemodialysis

● Caused by underlying disease: HTN, diabetes, nephrotic disease

● Plus abnormal lipid metabolism in ESRD● Increased synthesis of VLDL and decreased

clearance● diet restriction of fat; and use of lipid lowering

drugs may be used with high risk ESRD pts

Use of Parenteral Nutrition

❧When pt is too sick to eat, TPN may be required

❧More on TPN later

Renal Assignment

❧Page 801 Hemodialysis case study #1❧Do a nutrition assessment on pt❧Write in up in SOAP format that includes

Problem list in ‘A’ and solutions in ‘P’❧Include in the solution list a one day diet

based on appropriate intake of Kcal, fluid, Pro, K, P, and Na

❧Use exchange list on p 792 to help❧In addition, answer questions presented