1. Copyright © 2017, Elsevier Inc. All Rights Reserved.
Chapter 21
This chapter reviews the medical nutrition therapy (MNT) for people with various forms of kidney disease.
Dialysis extends the lives of patients with chronic kidney disease (CKD); however, it does so at an emotional, physical, and financial cost.
Kidney Disease
Copyright © 2017, Elsevier Inc. All Rights Reserved.

2. Lesson 21.1: Kidney Anatomy, Physiology, and Disease
Kidney disease interferes with the normal capacity of nephrons to filter waste products of metabolism.
Short-term kidney disease requires basic nutrition support for healing.
Lesson 21.1: Kidney Anatomy, Physiology, and Disease
Copyright © 2017, Elsevier Inc. All Rights Reserved. 2

3. Introduction
More than 114,000 Americans diagnosed with end-stage renal disease each year
Reduced kidney function often undiagnosed
Requires extensive medical nutrition therapy
Dialysis extends lives but carries high costs
The National Health and Nutrition Examination Survey found that 90% of individuals with more than two clinical markers for CKD are unaware of their condition.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 3

4. Basic Structure and Function of the Kidney
Kidneys filter about 1.2 L of fluid per minute
Structures
Nephron is the basic functional unit
Glomerulus: cluster of capillaries within the Bowman’s capsule filters the blood
Rate of filtration is the glomerular filtration rate (GFR)
Tubules: carry filtered fluid to kidney medulla
Basic Structure and Function of the Kidney
At the head of each nephron, a cup-shaped membrane referred to as Bowman’s capsule holds the entering blood capillary and its clump of smaller vessels.
Within Bowman’s capsule, the afferent arteriole branches into a cluster of capillaries to form the glomerulus.
Specific substances are reabsorbed and secreted by the four parts of the tubules.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 4

5. Basic Kidney Structure and Function
Anatomy of the kidney.
Top, Reprinted from Peckenpaugh NJ. Nutrition essentials and diet therapy. 11th ed. St. Louis, Saunders, Bottom, Reprinted from Thibodeau GA, Patton KT. Anatomy & physiology. 6th ed. St Louis: Mosby; 2007.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 5

6. Copyright © 2017, Elsevier Inc. All Rights Reserved.
From Thibodeau GA, Patton KT. Anatomy & physiology . 7th ed. St Louis: Mosby;
Basic Structure and Function (cont’d)
What is the glomerular filtration rate? (The rate at which blood is filtered through the glomerulus)
[Shown is Table 21-1, Reabsorption and Secretion in Parts of the Nephron.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 6

7. Proximal tubule: reabsorbs needed nutrients and returns them to blood
Loop of Henle: exchanges sodium, chloride, water
Distal tubule: secretes hydrogen ions as needed
Collecting tubule: produces concentrated urine
Influenced by
Antidiuretic hormone
Osmotic pressure
Tubules
The concentrated urine usually amounts to 1% or less of the filtered fluid.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 7

8. Function Excretory and regulatory functions
Filtration: removes most particles from blood except larger components of proteins and RBCs
Reabsorption: substances body needs are selectively reabsorbed and returned to blood to maintain electrolyte, acid-base, and fluid balances
Secretion: additional hydrogen ions secreted as needed to maintain acid-base balance
Excretion: waste materials excreted in the now concentrated urine
Function
At birth, each person has far more nephrons than are actually needed.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 8

9. Renin secretion: maintains hormonal control of body water balance
When the arteriole pressure falls, the kidneys activate and secrete renin.
Erythropoietin secretion: stimulate RBC production within bone marrow
Vitamin D activation: converts inactive form to final active vitamin D
Endocrine Functions
Renin initiates the renin-angiotensin-aldosterone system.
Parathyroid hormone activates the kidneys to convert vitamin D to its active form.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 9

10. Disease Process and Dietary Considerations
General causes of kidney disease
Infection and obstruction: bladder infections, kidney stones
Damage from other diseases: diabetes mellitus, hypertension, others less common
Toxins: environmental agents, animal venom, certain plants, heavy metals, some drugs
Genetic or congenital defects: cystic diseases, congenital abnormalities
Agents that are toxic to the kidneys are said to be nephrotoxic.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 10

11. General Causes of Kidney Disease
Risk factors
Diabetes, hypertension, cardiovascular disease
>60 years, obese, family history of kidney disease
Can a person born with only one kidney lead a healthy life without treatment? (Yes. Because of the abundance of nephrons at birth, people born with one kidney often are unaware of their condition and lead full lives.)
[Review Box 21-1, Risk Factors and Common Causes of Kidney Disease.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 11

12. Case Study
Mrs. Hendricks is a 65-year-old female who has poor glycemic control with her Type 2 diabetes of 32 years, has hypertension, and smokes 1 pack of cigarettes per day.  Her most recent glomerular filtration rate is 22 mL/min.
Case Study
What questions would you have about Mrs. Hendricks’ condition?
Copyright © 2017, Elsevier Inc. All Rights Reserved. 12

13. Case Study (cont’d)
What are Mrs. Hendrick’s risk factors for chronic kidney disease (CKD)?
CKD is also called end-stage renal disease (ESRD).
Risk factors for CKD:
Older age
Race
Poor glycemic control/diabetes
Hypertension
Smoker
Decreased glomerular filtration rate
Copyright © 2017, Elsevier Inc. All Rights Reserved. 13

14. Case Study (cont’d)
What clinical assessment parameters would be useful to find out from Mrs. Hendricks?
Some clinical symptoms might include:
Polyuria/oliguria/anuria, electrolyte imbalances, nitrogen retention, anemia, hypertension, azotemia, weakness, shortness of breath, fatigue, thirst, appetite loss, bleeding, muscular twitching
Copyright © 2017, Elsevier Inc. All Rights Reserved. 14

15. Medical Nutrition Therapy in Kidney Disease
Based on the severity of the disease, presence of metabolic abnormalities, and treatment modality
Length of disease: acute or chronic
Acute infection usually controlled with antibiotics
Chronic: more specific nutrient modifications
Degree of impaired kidney function
Extensive: extensive nutrition therapy required
Individual clinical symptoms
When a patient is being treated with dialysis, working closely with an RD for customized nutrition therapy is especially important.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 15

16. Nephron Diseases Acute glomerulonephritis or nephritic syndrome
Disease process: inflammatory process that affects glomeruli
Clinical symptoms: hematuria, proteinuria, possible edema, mild hypertension
Oliguria and anuria may develop
Medical nutrition therapy: diet modifications usually not crucial for acute disease
Glomerulonephritis is one of the three most common causes of end-stage renal disease.
[Review Table 21-2, Glomerular Syndromes.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 16

17. Nephrotic Syndrome (Nephrosis)
Disease process: nephron tissue damage allows protein to pass into tubule
Clinical symptoms: hypoalbuminemia, edema, ascites, distended abdomen, reduced plasma protein level, with eventual malnutrition
Additional symptoms may include hyperlipidemia, lipiduria, blood clotting abnormalities, and imbalances in several minerals
With nephrosis, both filtration and reabsorption functions of the nephron are disrupted.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 17

18. Nephrotic Syndrome (cont’d)
Medical nutrition therapy:
Protein: moderate; total protein intake modifiable based on blood urea nitrogen and GFR
Energy: adequate to support nutrition status
Liberal complex carbohydrates to combat the catabolism of tissue protein and to prevent starvation ketosis
Fats: <30% total kcals
<200 mg cholesterol; limited trans fats
Sodium, potassium: sodium restricted at 1-2 g/day; both closely monitored
Calcium, phosphorus: 1 to 1.5 g/day calcium, maximum 12 mg/kg body weight per day phosphorus
Fluid: restricted according to output and losses
The primary goals of nutrition therapy are to control major symptoms and replace nutrients lost in the urine.
Sodium overload is difficult to treat because of the characteristic hypoalbuminuria and hypotension; therefore, careful monitoring is necessary.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 18

19. Lesson 21.2: Treatment of Kidney Disease
The progressive degeneration of chronic kidney disease requires dialysis treatment and nutrient modification in accordance with each individual’s disease status.
Current therapy for kidney stones depends more on basic nutrition and health support for medical treatment than on major food and nutrient restrictions.
Do you know someone with kidney disease? What do you notice about them?
Copyright © 2017, Elsevier Inc. All Rights Reserved. 19

20. Kidney Failure
Acute kidney injury is life threatening and thus a medical emergency.
Disease process
Prerenal: inadequate blood flow to kidneys and subsequent reduced GFR
Intrinsic: damage to a part of the kidney
Postrenal obstruction: obstruction of urine flow
Healthy kidneys may suddenly shut down after metabolic insult or traumatic injury, thereby causing a life-threatening situation.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 20

21. Acute Kidney Injury
Clinical symptoms: RIFLE classification system assesses severity of
Risk
Injury
Failure
Loss
End-stage kidney disease
Acute Kidney Injury Network (AKIN) criteria also used to classify AKI
Diagnostic criteria
Increase in serum creatinine and oliguria
Diminished urine output may be accompanied by proteinuria or hematuria.
Other symptoms include nausea, vomiting, fatigue, muscle weakness, swelling in the lower extremities, itchy skin, confusion, uremia, and malnutrition.
Water balance also becomes a crucial factor.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 21

22. Acute Kidney Injury (cont’d)
Continuous renal replacement therapy, which is a type of dialysis, may be needed to support kidney function for critical patients.
Medical nutrition therapy
Basic objective: improve or maintain nutrition status
Principle: prevent protein catabolism, electrolyte and hydration disturbance, acidosis, uremic toxicity
Enteral or parenteral nutrition may become necessary.
Highly individualized therapy focuses on the following: (1) treating the underlying cause; (2) preventing further kidney damage and complications from nutrient deficiencies; and (3) correcting any fluid, electrolyte, or uremic abnormalities.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 22

23. Chronic Kidney Disease (CKD)
Disease process:
Progressive breakdown of kidney tissue
Most often results from
Metabolic diseases with kidney involvement
Primary glomerular disease
Inherited diseases or congenital abnormality
Other causes: immune diseases, obstruction, infection, long-term use of nephrotoxic medications
Modifiable risk factors include blood pressure, glycemic control, and addressing dyslipidemia; reducing sodium intake; making necessary dietary adjustments to potassium, phosphorus, and protein intake; increasing physical activity; achieving a healthy body weight; and quitting smoking.
[Review Table 21-3, Stages of Chronic Kidney Disease.]
[Review Table 21-4, Recommended Nutrition Guidelines for Adults with Chronic Kidney Disease.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 23

24. Water balance: large amounts of dilute urine (polyuria) in early stages, followed by oliguria and finally anuria as disease progresses
Nitrogen retention of urea, producing azotemia
Electrolyte and mineral balance: metabolic acidosis
chronic kidney disease-mineral and bone disorder (CKD-MBD) or osteodystrophy
Anemia
Hypertension
CKD Clinical Symptoms
Anemia results because the kidneys cannot perform their normal function of stimulating RBC production through erythropoietin.
When blood flow to the kidney tissues is increasingly impaired, renal hypertension develops.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 24

25. CKD General Signs and Symptoms
Progressive weakness
Shortness of breath
Fatigue
Anemia
Swelling in the extremities
Itchy skin rashes
Possible anorexia, nausea, and vomiting worsening malnutrition and weight loss
CKD General Signs and Symptoms
Nervous system involvement may cause muscular twitching and peripheral neuropathy.
[Review Clinical Applications, Case Study: a Patient with Chronic Kidney Disease.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 25

26. Medical Nutrition Therapy
Monitor at regular intervals
Therapy:
Protein: usually limited to 0.6 to 0.8 g/kg body weight per day for those not on dialysis with a GFR < 30 mL/min
Energy: 23 to 35 kcal/kg/day
Sodium/potassium: may be restricted if indicated through blood values
Phosphorus/calcium: phosphorus may be restricted, generally to 800 to 1000 mg/day
Vitamins/minerals: MNT goal is to help patients meet needs for B-complex vitamins, vitamin C
Supplements of fat-soluble vitamins contraindicated
Fluid: intake balanced with output
Medical Nutrition Therapy
Some recommendations vary depending on whether the patient is receiving dialysis.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 26

27. Case Study (cont’d)
Mrs. Hendricks is in what stage of chronic kidney disease?
Mrs. Hendricks is in stage 4: Severely decreased GFR 15 to 29 mL/min. Mrs. Hendrick’s is at 22 mL/min.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 27

28. Case Study (cont’d)
Outline appropriate medical nutrition therapy plan of care for Mrs. Hendricks.
Goals
Reduce protein breakdown
Avoid dehydration or excess hydration
Correct acidosis
Correct electrolyte imbalances
Control fluid and electrolyte losses
Maintain optimal nutritional status
Maintain appetite and morale
Control complications of hypertension, bone pain, nervous system involvement
Slow rate of renal failure
Principles
Provide enough protein therapy to maintain tissue integrity while avoiding excess
Provide amino acid supplements for protein supplementation as necessary
Reserve protein for tissue synthesis by ensuring adequate carbohydrates and fats
Maintain adequate urine volume with water
(Possibly) restrict sodium, phosphate, calcium as necessary
Supplement diet with B vitamins and vitamin C as necessary
Copyright © 2017, Elsevier Inc. All Rights Reserved. 28

29. End-Stage Renal Disease (ESRD)
Disease process
Patient, family, physician face life-support decisions
Irreversible damage to majority of nephrons
Options are long-term dialysis or kidney transplant
Two types of dialysis: hemodialysis and peritoneal dialysis
Dialysis is the chief treatment for end-stage renal disease.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 29

30. Copyright © 2017, Elsevier Inc. All Rights Reserved.
Hemodialysis
Artificial kidney machine removes toxins and restores metabolites and nutrients to normal blood levels
Usually 3 treatments per week , 3-4 hours each
Medical nutrition therapy
Protein: major concern of patients on dialysis to prevent protein malnutrition; g/kg/d typical
Energy: 25 to 35 kcal/kg/day
Sodium/potassium: 2-3 g/d for sodium; 2-4 g/d for potassium
Phosphorus/calcium: mg/d for phosphorus; 2 g/d maximum for calcium
Vitamins/minerals: achieve the DRI
Fluid: limited to 1 L/day plus amount equal to urine output
Medical nutrition therapy involves registered dietitians specializing in renal care.
Protein-energy malnutrition is considered one of the most significant predictors of overall malnutrition and adverse outcomes.
Iron and vitamin D intakes are individualized per patient on the basis of biochemical markers.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 30

31. Hemodialysis (cont’d)
Hemodialysis cleans and filters blood with a special filter called a dialyzer that functions as an artificial kidney.
Blood travels through tubes into the dialyzer, which filters wastes and extra water, and then the cleaned blood flows through another set of tubes and back into the body.
From National Institute of Diabetes and Digestive and Kidney Diseases. Treatment methods for hemodialysis. National Institutes of Health Publication No Bethesda, Md: National Institutes of Health; 2006.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 31

32. Hemodialysis (cont’d)
From National Institute of Diabetes and Digestive and Kidney Diseases. Kidney failure: choosing a treatment that's right for you. National Institutes of Health Publication No Bethesda, Md: National Institutes of Health; 2007.
Hemodialysis (cont’d)
The three basic kinds of vascular access for hemodialysis are arteriovenous fistula, arteriovenous graft, and a venous catheter.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 32

33. Peritoneal Dialysis About 9% of patients
Exchange of fluids occurs within the body (in peritoneal cavity), allows mobility
Medical nutrition therapy
Sodium/potassium: intake slightly more liberal
Same as for hemodialysis:
Protein and energy
Phosphorus/calcium,
Vitamins/minerals
Exception is thiamin, of which patients may need mg/d
Fluid
The treatment is a daily intensive therapy, and some patients experience more symptoms of depression and poorer self-reported physical health than patients treated with hemodialysis.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 33

34. Peritoneal Dialysis (cont’d)
Continuous ambulatory peritoneal dialysis.
[Review text Figure 21-5 (Part A is shown here).]
A soft tube catheter is used to fill the abdomen with a cleansing dialysis solution.
From National Institute of Diabetes and Digestive and Kidney Diseases. Treatment methods for kidney failure: peritoneal dialysis. National Institutes of Health Publication No Bethesda, Md: National Institutes of Health; 2006.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 34

35. Transplantation Improves quality of life and survival rates
More cost effective than maintenance dialysis
Waiting lists can be long and donor matches difficult to find, even when using expanded-criteria donors (matches with more liberal criteria).
Medical nutrition therapy for patients awaiting kidney transplantation is highly individualized.
[Review Drug-Nutrient Interaction, Immunosuppressive Therapies after Kidney Transplantation.]
[Review Cultural Considerations, Cultural Disparities in Kidney Transplant Availability and Success in Certain Ethnic and Racial Groups.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 35

36. ESRD
Complications
Complications of ESRD and dialysis: bone disorders, malnutrition, anemia, hormonal and blood pressure imbalances, depression, reduced quality of life
Nutrition support: when medically necessary, enteral or parenteral feedings customized to dialysis; reference American Society for Parenteral and Enteral Nutrition for specific guidelines
Nutrition support for kidney transplantation patients is highly individualized.
[Osteodystrophy and neuropathy are reviewed on the next slide.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 36

37. ESRD Complications (cont’d)
Bone disease and disorders common with CKD
Decreased activation of vitamin D has cascading effect
Osteodystrophy
Toxic substances accumulate in the blood, resulting in a uremic state, damaging nerves
Central and peripheral disturbances may be present at initiation of dialysis
Patients should be periodically assessed
Neuropathy
Patients with any level of kidney dysfunction should be evaluated for bone disease.
Addressing pain management is an important aspect of health care to maintain quality of life in patients with ESRD.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 37

38. Kidney Stone Disease Etiology of nephrolithiasis is unknown
Factors relating to urine or urinary tract environment contribute to formation
Affects ~7% of U.S. women and 11% of U.S. men
Majority of stones are formed from one of three substances:
Calcium
Struvite
Uric acid
[Review Box 21-2 for the risk factors for kidney stone development.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 38

39. Kidney Stone Disease (cont’d)
Renal calculi: stones in the kidney, renal pelvis, and ureter.
[Review Box 21-3, High-Oxalate Foods and Drinks.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 39

40. Calcium Stones Most common type: 80% of cases Possible causes:
Excess calcium in the blood (hypercalcemia) or urine (hypercalciuria)
Excess oxalate (hyperoxaluria) or uric acid in the urine (hyperuricosuria)
Low levels of citrate in the urine (hypocitraturia)
Long-term megadosing (more than 2 grams/day) of vitamin C a possible factor
Dietary calcium intake inversely related to calcium oxalate stone formation
It is a common error to limit calcium intake in persons who form calcium oxalate stones.
Individuals with a low dietary intake of calcium are at a higher risk for calcium oxalate stone formation than those who consume the DRI for calcium.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 40

41. Struvite Stones 10% of all stones
Caused primarily by urinary tract infection
No diet therapy is needed
Usually surgically removed
These are often called “infection stones.”
They are composed of magnesium ammonium phosphate and carbonate apatite.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 41

42. Hyperuricosuria may be caused by impairment of purine metabolism with some diseases
~9% of stones
Risk factors:
Overly acidic urine
Excess urinary excretion of uric acid
Low urine volume
Other stones
From inherited disorders or complications of medications
Uric Acid Stones
Uric acid stones may occur with gout; rapid tissue breakdown during wasting disease; or with diarrheal illness, type 2 diabetes, obesity, and metabolic syndrome.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 42

43. Clinical Symptoms of Kidney Stones and Medical Nutrition Therapy
Severe pain, urinary symptoms, weakness, + fever
Medical nutrition therapy depends on type of stone
Energy: customized to achieve an ideal body weight
Protein: no more than DRI
Calcium: normal calcium intake
Sodium: <2300 mg/day
Potassium: >4.7 g/day
Oxalates: avoid!
Vitamins/minerals: limit vitamin C to DRI; others meet DRI
Fluid: high intake
A large fluid intake helps to dilute urine and prevent the accumulation of materials that form stones.
Excessive protein intake from animal sources is a risk factor for stone formation.
[Table 21-5, Summary of Dietary Principles In Kidney Stone Disease.]
Copyright © 2017, Elsevier Inc. All Rights Reserved. 43

44. Objectives Specific to Type of Stone
Calcium oxalate stones: reduce dietary intake of oxalate; consider fiber intake
Calcium phosphate stones: control sources of phosphorus consider fiber intake
Uric acid stones: raise urinary pH and maintain healthy weight by consuming vegetarian-type diet and limiting animal protein
Cystine stones: reduce intake of cystine and methionine, reduce sodium intake, increase the intake of vegetables high in organic anions; and dilute the urine
A variety of medications are useful for the treatment of kidney stones in combination with diet therapy.
For medications to be most effective, the specific type of stone must be identified.
This is not always possible and therefore limits drug therapy in some individuals.
Copyright © 2017, Elsevier Inc. All Rights Reserved. 44