The association between dietary protein and serum phosphate level on chronic hemodialysis patients

Taipei Medical University

T

he

a

ssociation

b

etween

d

ietary

p

rotein

a

nd

s

erum

p

hosphate

l

evel

o

n

c

hronic

h

emodialysis

p

atients

I

ntroduction

O

bjective

Dietary phosphorus always exists with protein food.

To have daily protein intake above 1.2 g/kg to achieve

the K/DOQI recommends may conflict with phosphorus

restriction on chronic hemodialysis (CHD) patients.

S

ubjects and Methods

R

esults and Discussion

C

onclusion

Lin WC

_{, Jin MY}

_{, Chen TH}

_{, Yang SH}

1

_{School of Nutrition and Health Sciences, Taipei Medical University}

_{Department of Nutrition, Wanfang Hospital}

_{Department of Internal Medicine, Wanfang Hospital}

_{Nutrition research center, Taipei Medical University Hospital}

To evaluate the association between dietary protein

and serum phosphate level on CHD patients.

Eighty three subjects were recruited from CHD

patients in Wanfang Hospital in 2010. We collected

demographic data, anthropometric and laboratory

measurements over 6 months and conducted

knowledge, attitude and practice (KAP) questionnaires to

evaluate subjects’ awareness of adequate nutrition,

dietary phosphorus and food choice.

Table1. Comparison of KAP scores between younger and older subjects (n=73). score Younger (n = 39) Older (n = 34) p Knowledge score 20 10.9 ± 0.7* 5.6 ± 1.0 0.001 Attitude score 40 28.9 ± 1.6* 13.2 ± 2.7 0.000 Practice score 40 20.4 ± 1.2 19.7 ± 1.5 0.678 Total score 100 60.2 ± 3.0* 38.5 ± 4.2 0.000

Values are expressed as mean ±SE. Values with different superscripts are significantly different at p < 0.05 by Student’s t test.

Younger CHD patients has higher knowledge and

attitude scores, but no good compliance (table1). Over 6

months, protein intake (nPCR) increased significantly and

maintained nutritional status (includes GNRI and serum

albumin), while elevated serum phosphate and potassium

levels (table 2). Serum phosphate and Ca × P level

significantly correlated with nutritional parameters (includes

total protein level, albumin and protein intake). Most of

processed foods are enriched with phosphorus and

potassium. Subjects with poor food choice of high-protein

food may lead to improper control of serum phosphate and

potassium.

High protein with lower phosphorus food choice is

important for controlling serum phosphate level among

CHD patients. We suggest that fresh and high biological

value (HBV) protein food should be substituted for

processed food.

Table3. Correlation of serum phosphate and calcium phosphate product (Ca × P) and univariate variables, adjust age and sex.

Serum phosphate Ca × P r p r p Total protein 0.15* 0.032 0.19* 0.006 Albumin 0.23* 0.001 0.32* 0.000 GNRI 0.27* 0.000 0.35* 0.000 nPCR 0.24* 0.001 0.26* 0.000

Values are correlation coefficients and p value. GNRI, geriatric nutritional risk index; nPCR, normalized protein catabolic ration.Values with different superscripts are significantly different at p < 0.05 by using partial correlation.

Table2.Comparison of anthropometric, laboratory and indicator of nutritional status between 6 months.

Subjects (n=83) _p

Baseline Month1 Month2 Month3 Month4 Month5 Month6

BUN, mg/dL 76.2 ± 2.3c _{79.8 ±2.2}b _{82.3 ± 2.1}b _{85.9 ± 2.2}a _{84.2 ± 2.3}ab _{84.7 ±2.2}ab _{84.4 ± 2.2}ab _0.000 Cr, mg/dL 11.5 ± 0.3bc _{11.4 ±0.3}b _{11.5 ± 0.3}b _{12.1 ± 0.3}a _{11.5 ± 0.3}b _{11.7 ±0.3}b _{11.3 ± 0.3}b _0.002 UA, mg/dL 8.7 ± 0.8 - - 7.9 ± 0.1 - - 8.1 ± 0.2 0.376 TP, g/dL 6.6 ± 0.1 - - 6.6 ± 0.1 - - 6.6 ± 0.1 0.228 Albumin, g/dL 3.8 ± 0.0b _{3.7 ±0.0}b _{3.8 ± 0.0}ab _{3.8 ± 0.0}ab _{3.8 ± 0.0}ab _{3.9 ±0.0}a _{3.8 ± 0.0}ab _0.122 GNRI 95.6 ± 0.8b _{95.1 ±0.9}b _{95.9 ± 0.9}ab _{96.2 ± 0.9}a _{95.4 ± 0.9}ab _{96.9 ±0.8}a _{96.3 ± 0.8}ab _0.130 nPCR, g/kg 1.06 ± 0.03b _{- - 1.14 ± 0.03}a _{- - 1.12 ± 0.04}a _0.009 TG, mg/dL 182 ± 14a _{- - 172 ± 14}ab _{- - 159 ± 13}b _0.064 TC, mg/dL 159 ± 4 - - 160 ± 4 - - 162 ± 5 0.847 HGB, mg/dL 10.0 ± 0.2b _{10.1 ±0.1}ab _{10.3 ± 0.2}ab _{10.3 ± 0.1}a _{10.3 ± 0.1}a _{9.9 ±0.2}b _{10.0 ± 0.1}b _0.006 Ferritin, ng/mL 641 ± 57a _{- - 602 ± 60 - - 582 ± 55}b _0.084 Ca, mg/dL 9.0 ± 0.1b _{9.1 ±0.1}a _{9.1 ± 0.1}a _{8.9 ± 0.1}b _{9.1 ± 0.1}b _{8.8 ±0.1}c _{8.9 ± 0.1}bc _0.000 P, mg/dL 5.2 ± 0.1b _{5.3 ±0.2}ab _{5.3 ± 0.2}ab _{5.6 ± 0.2}ab _{5.7 ± 0.2}ab _{5.7 ±0.2}a _{5.6 ± 0.2}ab _0.164 Ca × P, mg2_/dL2 _{47.1 ± 1.4 48.6 ±1.7 48.8 ± 1.6 50.2 ± 1.6 51.6 ± 1.9 51.0 ±1.7 50.3 ± 1.8 0.382} K, mEq/L 4.7 ± 0.1b _{4.7 ±0.1}b _{4.7 ± 0.1}b _{4.8 ± 0.1}b _{5.0 ± 0.1}a _{4.9 ±0.1}a _{4.8 ± 0.1}b _0.000 Kt/V 1.70 ± 0a _{1.67 ±0.03}ab _{1.62 ± 0.04}ab _{1.64 ± 0.03}b _{1.63 ± 0.03}ab _{1.61 ±0.04}b _{1.64 ± 0.04}b _0.076 Values are expressed as mean ± SE. BUN, blood urea nitrogen; Cr, creatinine; UA, uric acid; BMI, body mass index; TP, total protein; GNRI, geriatric nutritional risk index; nPCR, normalized protein catabolic ratio; TG, triglyceride; TC, total cholesterol; HGB, hemoglobin; Ca, calcium; P, phosphate; Ca × P, calcium phosphate product; K, potassium. Values with different superscripts are significantly different at p < 0.05 by one-way repeated measures ANOVA.