Nutrition of patients undergoing dialysis.. nutritional assessments..proteins, fats.. and others...

2. Introduction
Nutritional Aspects in Dialysis
• The results of cross-sectional studies throughout the world indicate that
dialysis patients are at very high risk of malnutrition.
• Malnutrition in renal failure is multifactorial, but inadequate oral intake is a
major contributing factor.
• Protein-energy intake is often reduced because of inappropriate dietary
restrictions, anorexia, emotional distress and taste alterations, promoting
malnutrition in most patients entering dialysis.
• In addition, losses of nutrients, including glucose, amino acids, proteins, and
vitamins, occur during the dialysis treatment.
• Gastrointestinal complaints are also frequently seen in this patient
population and contribute to decreased intake and malnutrition.
• Similarly, frequent blood sampling, sequestration of blood in hemodialyzer
and tubing, and accumulation of endogenous toxins can also be the reason.

3. Nutritional Assessment
• Nutritional assessment requires interpretation of a
combination of clinical and biochemical parameters.
• Physical examination for clinical signs of poor nutrition
or nutritional deficiency (appearance of skin, hair, lips,
tongue, gums, nails, and overall presence of
subcutaneous fat loss or muscle wasting) should be
looked for. Regular monitoring of dry weight is
essential to highlight changes in body weight over
time.

4. Body composition:
• Various methods include anthropometric
measurements using calipers and a tape
measure, commonly mid-upper arm
circumference (MUAC) and triceps skin
fold thickness (TSF); mid-arm muscle
circumference (MAMC) can then be
calculated. Comparison with standards
must use renal anthropometric tables.
Serial measurements are of more
significance to highlight changes in muscle
mass or fat. Other measures include
bioelectrical impedance (BIA), dual-
energy X-ray analysis (DEXA), and
magnetic resonance imaging (MRI).

5. Bioelectrical impedance test

6. Functional assessment:
• Review activities of daily living and the ease of basic physical activity
(stair climbing or walking). Muscle strength can be determined using
hand-grip dynamometry.

7. Subjective global assessment (SGA):
• Uses eight clinical measures including dietary intake, co-morbid
disease, or GI symptoms, physical examination, changes in body
weight, and functional capabilities to produce a semiquantitative
nutritional assessment. An overall assessment of nutritional status is
generated from the scores in each category.

8. Dietary Interviews and Diaries:
• Dietary interviews and/or diaries are valid and clinically useful for
measuring dietary protein and dietary energy intake in maintenance
dialysis patients.

9. Serum Albumin:
• Serum albumin is a valid and clinically useful measure of protein-energy
nutritional status in maintenance dialysis (MD) patients.
• The serum albumin at the time of initiation of chronic dialysis therapy or during
the course of maintenance dialysis is an indicator of future mortality risk.
• A predialysis or stabilized serum albumin equal to or greater than the lower limit
of the normal range (approximately 4.0 g/dL for the bromcresol green method) is
the outcome goal.
• Individuals with a predialysis or stabilized serum albumin that is low should be
evaluated for protein-energy malnutrition.
• The presence of acute or chronic inflammation limits the specificity of serum
albumin as a nutritional marker. Hence, hypoalbuminemia in MD patients does
not necessarily indicate protein-energy malnutrition (PEM). The patient’s clinical
status (eg. comorbid conditions, dialysis modality, acid-base status, degree of
proteinuria) must be examined when evaluating changes in the serum albumin
level.

10. Serum Prealbumin:
• An individual with pre-dialysis or stabilized serum prealbumin less
than 30 mg/dL should be evaluated for protein-energy malnutrition.
• The presence of acute or chronic inflammation limits the specificity of
serum prealbumin as a nutritional marker.
• But, It has been suggested that serum prealbumin may be more
sensitive than albumin as an indicator of nutritional status, since it
has a shorter half-life than albumin (2 to 3 days versus 20 days,
respectively).

11. Serum Creatinine and the Creatinine Index:
• The predialysis or stabilized serum creatinine and the
creatinine index reflect the sum of dietary intake of
foods rich in creatine and creatinine (eg. skeletal
muscle) and endogenous (skeletal muscle) creatinine
production minus the urinary excretion, dialytic
removal, and endogenous degradation of creatinine.
• Individuals with low predialysis or stabilized serum
creatinine (less than approximately 10 mg/dL) should
be evaluated for protein-energy malnutrition and
wasting of skeletal muscle.
• A low creatinine index and, in the absence of substantial
endogenous urinary creatinine clearance, a low serum
creatinine concentration suggest low dietary protein
intake (DPI) and/or diminished skeletal muscle mass and
are associated with increased mortality rates.

12. Serum Cholesterol
• Low or declining serum cholesterol concentrations are predictive of
increased mortality risk.
• Hypocholesterolemia is associated with chronic protein-energy deficits
and/or the presence of comorbid conditions, including inflammation.
• Individuals with low, low-normal (less than approximately 150 to 180
mg/dL), or declining serum cholesterol levels should be investigated for
possible nutritional deficits.

13. Protein Equivalent of Total Nitrogen Appearance (PNA):
• The protein equivalent of total nitrogen appearance (PNA) or UNA can be
calculated by adding together urinary and dialysate nitrogen and the
changes in total body urea nitrogen.
• Nitrogen Balance= DNI - UNA - NUN - DNPL – UNPL
Where, DNI = dietary nitrogen intake, estimated as DPI/6.25; UNA = urea
nitrogen appearance; NUN = non-urinary nitrogen, estimated as 31 mg/kg;
DNPL = dialysate nitrogen protein losses; UNPL = urinary nitrogen protein
losses.
• When nitrogen balance is zero in the steady state, the difference between
nitrogen intake and total nitrogen losses is zero or only slightly positive (ie,
up to about 0.5 g nitrogen/d because of unmeasured nitrogen losses).
• Hence, in the clinically stable patient, PNA provides a valid estimate of
protein intake.

14. Adjusted Edema-Free Body Weight (aBWef)
• The body weight to be used for assessing or prescribing protein or
energy intake is the aBWef. For hemodialysis patients, this should be
obtained post dialysis. For peritoneal dialysis patients, this should be
obtained after drainage of dialysate.
Where, BWef is the actual edema-free body weight and SBW is the
standard body weight

15. • The adjusted edema-free body weight should be used for
maintenance dialysis patients who have an edema-free body weight
less than 95% or greater than 115% of the median standard weight.
• For individuals whose edema-free body weight is between 95% and
115% of the median standard weight, the actual edema-free body
weight may be used.

16. Acid-base status:
• Serum bicarbonate should be measured in maintenance dialysis
patients once monthly.
• Pre dialysis or stabilized serum bicarbonate levels should be
maintained at or above 22 mmol/L.

17. Protein requirements
• The NKF K/DOQI (The National Kidney Foundation Disease Outcomes
Quality Initiative) Clinical Practice Guidelines on Nutrition in CRF
recommend 1.2 g protein/kg body weight/d for clinically stable
patients on maintenance hemodialysis (MHD).
• This level of protein intake should maintain neutral or positive
balance in almost all clinically stable patients undergoing MHD thrice
weekly.
• In patients on chronic ambulatory peritoneal dialysis, protein intake
should be 1.2–1.4 g/kg/d.

18. • Essential amino acids may be supplemented or can be administered
as their ketoanalogs.

19. Sodium and fluids
• Patients undergoing MHD or chronic peritoneal dialysis(CPD)
frequently are oliguric or anuric. For hemodialysis patients,
sodium and total fluid intake generally should be restricted to
1000–2000 mg/d and 1000–1500 mL/d, respectively.
• Because sodium and water can be removed easily with CAPD
or other forms of CPD, a more liberal salt and water intake is
usually allowed. Indeed, by maintaining a larger dietary
sodium and water intake, the quantity of fluid removed from
the CPD patient, and hence the daily dialysate outflow
volume can be increased.

20. Potassium
• Dietary potassium is generally restricted to
2000–3000 mg/d for patients requiring
hemodialysis and 3000–4000 mg/d for patients
requiring peritoneal dialysis.

21. Phosphorus
• The rationale for controlling dietary phosphorus and the use of GI binders of
phosphate is to prevent and treat hyperphosphatemia, a high serum calcium–
phosphorus product, calcium phosphate deposition in soft tissue, and
hyperparathyroidism.
• A dietary phosphorus restriction of 800–1000 mg/d should be implemented
when serum phosphorus rises to >4.6 mg/dL.
• A dietary phosphorus restriction of 800–1000 mg/d decreases the PTH levels
and may reduce bone resorption in those patients with elevated PTH.
• The National Kidney Foundation recommends that serum calcium–
phosphorus product be maintained at <55 mg/dL to prevent soft tissue
calcification. Calcium from phosphorus binders should be maintained below
1500 mg/d, and total calcium intake (supplements and diet) should not exceed
2000 mg/d.

22. Vitamins
• These deficiencies are severe after institution of dialysis therapy
because of the loss of water-soluble vitamins in dialysate on a thrice-
weekly regimen.
• 75–90 mg/d of vitamin C, 10–50 mg/d of pyridoxine, and 1–5 mg/d of
folate should be prescribed.
• Supplemental vitamin A is not recommended.
• Vitamin K often is not needed.
• Vitamin D should be supplemented to a plasma level >30 pg/mL.

23. Conclusion
• The estimation of nutritional needs and dietary modifications in
patients with CKD and dialysis, although challenging, can become
fairly easy with a close co-ordination between nephrologist, dietician,
and pharmacist.

24. Reference
1. Bajwa SS, Kwatra IS. Nutritional needs and dietary modifications in patients on dialysis and chronic
kidney disease. J Med Nutr Nutraceut 2013;2:46-51.
2. https://www.kidney.org/sites/default/files/docs/kdoqi2000nutritiongl.pdf
3. S. Mandolfo, A. Zucchi, L. Cavalieri D'Oro, B. Corradi and E. Imbasciati (1996) 'Protein nitrogen
appearance in CAPD patients: what is the best formula?', Nephrol Dial Transplant, 11(1), pp. 1592-1596.