NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Chung M, Moorthy D, Hadar N, et al. Biomarkers for Assessing and Managing Iron Deficiency Anemia in Late-Stage Chronic Kidney Disease [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2012 Oct. (Comparative Effectiveness Reviews, No. 83.)

Cover of Biomarkers for Assessing and Managing Iron Deficiency Anemia in Late-Stage Chronic Kidney Disease

Biomarkers for Assessing and Managing Iron Deficiency Anemia in Late-Stage Chronic Kidney Disease [Internet].

Show details

Appendix DTest Performance of Newer Markers for Assessing Iron Status as Defined by Classical Laboratory Markers

Methods for Statistical Analyses—Relationships Between Analytic Sensitivity and Specificity, and Test Agreement)

There is a lack of a generally-accepted reference standard test for determining iron deficiency in the setting of CKD.1 Thus, we can expect that both newer and the classical laboratory biomarkers of iron status can err, i.e., the results of either test could be different than the “true” iron status. In such a case, assessing concordance may be the only meaningful option if none of the compared tests is an obvious choice for a reference standard, e.g., when both tests are alternative methodologies to measure the same quantity.

When the original studies used classical markers of iron status to define iron deficiency and used it as the reference standard in calculating the test accuracy (sensitivity and specificity) of newer markers of iron status, we considered these data are analytic sensitivity and specificity (or technical test performance) of newer markers.2 To facilitate the interpretation of analytic sensitivity and specificity, whenever possible, we calculated Cohen’s kappa statistic. The Cohen’s kappa statistic can be calculated based on the 2×2 contingency tables that were used to estimate the sensitivity and specificity comparing a newer marker of iron status with a “reference standard,” as defined by the classical markers of iron status in the original studies. We used the Landis and Koch3 interpretation of values of kappa to determine the level of agreement: <0, poor agreement; 0 to 0.20, slight agreement; 0.21 to 0.4, fair agreement; 0.41 to 0.60, moderate agreement; 0.61 to 0.80, substantial agreement; 0.81 to 1.0, almost perfect agreement.

When Cohen’s kappa statistic could not be calculated due to insufficient data in the original studies, we used a graph that visualized the relationships between sensitivity, specificity, and kappa to aid our interpretations of the test agreements, based on the reported sensitivities and specificities (Figure D1).4 This graph was produced based on the formulas describing the analytic relationship between sensitivity, specificity, kappa, and raw agreement for the 2×2 contingency tables. Four curves representing the ceiling of the four kappa coefficients were plotted on a squared space of sensitivity and specificity values. The curves provide all of the sensitivities and specificities pairs below which kappa cannot be achieved. For example, for k = 0.8 (which is considered to indicate substantial agreement), the line, sensitivity equal to specificity, intersects the elliptical curve for k = 0.8 exactly at (0.9, 0.9). Thus, these sensitivities and specificities, both of which are below 0.9, can never produce a kappa of 0.8 or greater.

Four curves representing the ceiling of the four kappa coefficients were plotted on a squared space of sensitivity values, on the horizontal axis, and specificity values, on the vertical axis. The curves provide all of the sensitivities and specificities pairs below which kappa cannot be achieved. For example, for k = 0.8 (which is considered to indicate substantial agreement), the line, sensitivity equal to specificity, intersects the elliptical curve for k = 0.8 exactly at (0.9, 0.9).

Figure D1

Relationships between statistical measures of test performance: analytic sensitivity and specificity, and kappa (k) statistic.

Results—Concordance Between Newer Markers and Classical Markers of Iron Status

In this section, we summarize the findings from 15 cross-sectional studies evaluating the test performance of newer markers for assessing iron status as defined by classical laboratory markers.519 Thirteen studies enrolled adult hemodialysis (HD CKD) patients. One study enrolled adult peritoneal dialysis (PD CKD) and nondialysis (ND CKD) patients,11 and another study enrolled pediatric HD and PD CKD patients.10 Many of these studies evaluated more than one newer marker, including content of hemoglobin in reticulocytes (CHr), percent hypochromic red blood cells (%HYPO), reticulocyte hemoglobin content (RetHe), soluble transferrin receptor (sTfR), and erythrocyte zinc protoporphyrin (ZPP). Studies used a variety of definitions for iron deficiency using classical laboratory markers, such as transferrin saturation (TSAT) or ferritin.

As described in the Methods, “reference standard” tests for determining iron deficiency in the context of CKD are lacking, and both newer and classical laboratory markers are subject to measurement errors. Thus, whenever it is possible, we either calculated Cohen’s kappa statistic based on the 2×2 contingency tables or estimated kappa based on a graph depicting the relationships between sensitivity, specificity, and kappa to aid our interpretation of test agreements (Figure D1).4

Summary of Key Points

  • Among adult HD CKD patients:
    • Content of hemoglobin in reticulocytes (CHr) and classical laboratory markers (TSAT or ferritin, alone or in combination) have poor to moderate test agreements.
    • Percent hypochromic red blood cells (%HYPO) and classical laboratory markers (TSAT or ferritin, alone or in combination) have poor to fair agreements.
    • Soluble transferring receptor (sTfR) and classical laboratory markers (TSAT or ferritin, alone or in combination) have poor to fair agreements.
    • Erythrocyte zinc protoporphyrin (ZPP) and classical laboratory marker (TSAT<20%) have poor to fair agreements for assessing iron status in HD CKD patients with normal iron store as indicated by serum ferritin concentrations (>100 ng/mL). Higher ZPP cutoffs were associated with better agreements with TSAT <20%.

Content of Hemoglobin in Reticulocytes

Key Points

Seven cross-sectional studies, enrolling a total of 911 adult HD CKD patients (individual counts ranged from 22 to 217 patients in each study),6,7,9,15,16,18,19 and one cross-sectional study with 19 PD CKD patients,11 evaluated the test performance of CHr for assessing iron status as defined by classical laboratory markers. Studies enrolled primarily older patients who received maintenance ESA treatment; however, maintenance ESA doses varied across studies. Baseline iron status (based on mean serum ferritin and TSTA concentrations) also varied across studies.

CHr and classical laboratory markers (TSAT or ferritin) have poor to moderate agreements for assessing iron status in HD CKD patients.

Detailed Synthesis

(Table D1 to D3)

Seven cross-sectional studies, enrolling a total of 833 adult HD CKD patients (individual counts from 22 to 217 patients in each study),6,7,9,15,16,18,19 and one cross-sectional study with 19 PD CKD patients,11 evaluated the test performance of CHr for assessing iron status as defined by classical laboratory markers. Four studies were conducted in Japan, two in the U.K., one in Germany, and one in South Korea. Studies enrolled primarily older men and women (mean age ranged from 49 to 62 years old). Baseline mean Hb concentrations ranged from 9.4 to 10.3 g/dL (reported in 5 studies). Four of the eight studies reported a mean ferritin concentration less than 100 ng/mL (indicating an insufficient iron store status),6,7,18,19 while the other four reported a mean ferritin concentration greater than 100 ng/mL at baseline (ranging from 198 to 427 ng/mL).9,11,15,16 Baseline mean TSAT ranged from 20 to 32 percent. Most patients received maintenance ESA treatment (one study enrolled 29 patients who had not received ESA treatment), but the maintenance ESA doses varied across studies (Table D1).

Table D1. Characteristics of cross-sectional studies evaluating the test performance of reticulocyte hemoglobin content (CHr) for assessing iron status as defined by classical laboratory markers.

Table D1

Characteristics of cross-sectional studies evaluating the test performance of reticulocyte hemoglobin content (CHr) for assessing iron status as defined by classical laboratory markers.

The test performance of CHr was assessed using four different reference standards of iron status as defined by classical laboratory markers: 1) TSAT ≤15%;9 2) TSAT ≤20%;6,7,15,19 3) ferritin ≤100 ng/mL;7 and 4) TSAT ≤20% or ferritin ≤100 ng/mL.11,15,16,18 Seven studies used variable CHr cutoffs to define iron deficiency (ranging from <26 to <35 pg),6,7,9,15,16,18 of which only two both used cutoffs of CHr <31 and <32 pg.16,18 One study analyzed the test performance of CHr as a continuous measure.19

The reported sensitivity and specificity pairs at different CHr cutoffs, as well as the estimated agreements between CHr and classical markers of iron status, are summarized in Tables D2 and D3. Seven studies (6 studies in HD CKD patients and 1 study in PD CKD patients) showed poor to moderate test agreements between CHr and classical markers of iron status.6,7,9,11,15,16,18 Most studies were small in sample size (N<100) and thus cannot provide precise test agreement estimates. Moreover, the heterogeneity in the test comparisons, iron status of the study populations, and background treatment may explain the inconsistencies in the test agreements across studies.

Table D2. Summary of results for the test agreements between reticulocyte hemoglobin content (CHr) and classical markers of iron status.

Table D2

Summary of results for the test agreements between reticulocyte hemoglobin content (CHr) and classical markers of iron status.

Table D3. Study results for reticulocyte hemoglobin content (CHr)—assessing iron status as defined by classical laboratory markers.

Table D3

Study results for reticulocyte hemoglobin content (CHr)—assessing iron status as defined by classical laboratory markers.

Another study of 149 HD CKD patients performed multivariate analyses, and showed that Chr was the most significant predictor among the markers examined (including hematocrit, %HYPO, log ferritin, sTfR, and epoetin user status). The multivariate analyses also showed that each 1 pg decrease in CHr and one standard deviation decrease (equivalent to 2.25 pg) in CHr were associated with a 1.88 (95 percent CI, 1.39 to 2.53) and 4.11 (95 percent CI, 2.10 to 8.05) fold increase, respectively, in the odds of iron deficiency (defined as TSAT < 20 percent).19

Percent Hypochromic Red Blood Cells

Key Points

Four cross-sectional studies, with a total of 495 adult HD CKD patients (per study enrollment ranged from 72 to 202 patients) evaluated the test performance of CHr for assessing iron status as defined by classical laboratory markers.7,9,17,19 Studies enrolled primarily older patients who received maintenance ESA treatment, although the maintenance ESA doses varied from study to study. Baseline iron status, based on mean serum ferritin and TSAT concentrations, also varied across studies.

Overall, %HYPO and classical laboratory markers (TSAT or ferritin) have poor to fair agreements for assessing iron status in HD CKD patients.

Detailed Synthesis

(Table D4 to D6)

Four cross-sectional studies, with a total of 495 adult HD CKD patitents, evaluated the test performance of %HYPO for assessing iron status as defined by classical laboratory markers.7,9,17,19 Studies were conducted in several different countries: the U.K., Germany, Poland, and Japan. All studies enrolled primarily older men and women (mean age ranged from 55 to 64 years old). Baseline mean Hb concentrations ranged from 8.8 to 10.2 g/dl (reported in 3 studies). Of the four included studies, two reported a mean ferritin concentration less than 100 ng/mL (indicating an insufficient iron store status),7,19 and the other two reported a mean ferritin concentration of 274 and 427 ng/mL at baseline.9,17 Baseline mean TSAT ranged from 20 to 38 percent across studies. Most patients received maintenance ESA treatment (a total of 74 patients did not received ESA treatment), although the maintenance ESA doses varied across studies (Table D4).

Table D4. Characteristics of cross-sectional studies evaluating the test performance of percent hypochromic red blood cell (%HYPO) for assessing iron status as defined by classical laboratory markers.

Table D4

Characteristics of cross-sectional studies evaluating the test performance of percent hypochromic red blood cell (%HYPO) for assessing iron status as defined by classical laboratory markers.

The test performance of %HYPO was assessed using three different reference standards of iron status (as defined by classical laboratory markers): 1) TSAT ≤ 15%;9 2) TSAT ≤ 20%;7,17,19 and 3) ferritin ≤100 ng/mL.7 Three studies used variable %HYPO cutoffs to define iron deficiency ranging from >1.5% to >10%,9,17 with two studies using the same cutoffs of >5% and >10%. One study analyzed the test performance of %HYPO as a continuous measure.7

The reported sensitivity and specificity pairs at different %HYPO cutoffs, as well as the estimated agreements between %HYPO and classical markers of iron status, are summarized in Tables D5 and D6. Three studies showed poor to fair test agreements between %HYPO and classical markers of iron status in HD CKD patients,7,9,17 one of which also reported that %HYPO “failed to show as a strong performance as measure of iron deficiency” based on ROC analyses.7 The heterogeneity in the test comparisons, iron status of the study populations, and background treatment may explain the inconsistencies in the test agreements across studies.

Table D5. Summary of results for the test agreements between percent hypochromic red blood cell (%HYPO) and classical markers of iron status.

Table D5

Summary of results for the test agreements between percent hypochromic red blood cell (%HYPO) and classical markers of iron status.

Table D6. Study results for percent hypochromic red blood cell (%HYPO)—iron status as defined by classical laboratory markers.

Table D6

Study results for percent hypochromic red blood cell (%HYPO)—iron status as defined by classical laboratory markers.

Another study, enrolling149 HD CKD patients, showed that, when compared to a %HYPO ≤1.5 percent, a %HYPO ≥4.1% and a %HYPO between 1.6 and 4.0% were associated with a respective 8.53 (95 percent CI, 3.42 to 21.26) and 2.20 (95 percent CI, 0.88 to 5.48) fold increase in the odds of iron deficiency (defined as a TSAT < 20 percent).19 However, %HYPO was not a significant predictor of iron deficiency in a multivariate model including other markers (including hematocrit, CHr, log ferritin, sTfR, and epoetin user status).

Reticulocyte Hemoglobin Equivalent

Key Points

Three cross-sectional studies, enrolling more than 270 adult HD CKD patients (one study included 1500 samples from an unclear number of patients),8,14,18 and one cross-sectional study with 19 PD CKD patients and an unclear number of ND CKD patients,11 evaluated the test performance of RetHe for assessing iron status as defined by classical laboratory markers. Studies enrolled primarily older patients who received maintenance ESA treatment, although the maintenance ESA doses varied across studies. Baseline iron status, based on mean serum ferritin and TSTA concentrations, also varied across studies.

One study examined the test performance of RetHe using two different reference standards, and showed that the test performance of RetHe was less favorable for assessing functional iron deficiency than for assessing traditional parameters for iron deficiency in HD CKD patients.8

Detailed Synthesis

(Table D7 to D9)

Three studies, enrolling more than 270 adult HD CKD patients (one study included 1500 samples from an unclear number of patients),8,14,18 and one cross-sectional study with 19 PD CKD patients and an unclear number of ND CKD patients11 evaluated the test performance of RetHe for assessing iron status as defined by classical laboratory markers. Two studies were conducted in Japan, one in the U.S., and one in Bosnia and Herzegovia. Studies enrolled primarily older men and women (mean age ranged from 49 to 65 years old). One study did not report any information on patients’ background treatment or anemia or iron status.8 In the other three studies, baseline mean Hb concentrations ranged from 9.8 to 11.3 g/dL. One study reported a mean ferritin concentration of less than 100 ng/mL (indicating an insufficient iron store status),18 while the other two reported a mean ferritin concentration greater than 100 ng/mL at baseline (139 and 559 ng/mL).11,14 Baseline mean TSAT ranged from 20 to 39 percent across studies. All patients received maintenance ESA treatment, although the maintenance ESA doses varied across studies (Table D7).

Table D7. Characteristics of cross-sectional studies evaluating the test performance of reticulocyte hemoglobin equivalent (RetHe) for assessing iron status as defined by classical laboratory markers.

Table D7

Characteristics of cross-sectional studies evaluating the test performance of reticulocyte hemoglobin equivalent (RetHe) for assessing iron status as defined by classical laboratory markers.

The test performance of RetHe was assessed using four different reference standards of iron status (as defined by classical laboratory markers): 1) TSAT ≤20% and ferritin ≤100 ng/mL;11,14 2) TSAT ≤20% or ferritin ≤100 ng/mL;18 3) serum iron < 40 μg/dL, TSAT<20%, ferritin <100 ng/mL, and Hb <11 g/dL;8 and 4) TSAT<20%, ferritin 100–800 ng/mL, and Hb <11 g/dL.8 No two studies used the same reference standard in the same patient population (i.e., HD CKD, PD CKD, or ND CKD patients). The RetHe cutoffs that were used to define iron deficiency ranged from <27.2 to < 35 pg, and no studies used the same cutoffs of RetHe. Thus, the consistencies of study findings cannot be assessed.

The reported sensitivity and specificity pairs at different RetHe cutoffs, as well as the estimated agreements between RetHe and classical markers of iron status are summarized in Tables D8 and D9. The three studies in HD CKD patients showed poor to moderate test agreements between RetHe and classical markers of iron status.8,14,18 One study examined the test performance of RetHe using two different reference standards: “traditional parameters for iron deficiency” (serum iron < 40 μg/dL, TSAT<20%, ferritin <100 ng/mL, and Hb <11 g/dL) and “functional iron deficiency” (TSAT<20%, ferritin 100–800 ng/mL, and Hb <11 g/dL). This study showed that the test performance of RetHe was less favorable for assessing functional iron deficiency than for assessing traditional parameters for iron deficiency in HD CKD patients (areas under the curve were 0.657 vs. 0.913, respectively).8 However, this study had an unclear descriptions of the study population and incorrect statistical analyses due to nonadjustment for within-patient correlation.

Table D8. Summary of results for the test agreements between reticulocyte hemoglobin equivalent (RetHe) and classical markers.

Table D8

Summary of results for the test agreements between reticulocyte hemoglobin equivalent (RetHe) and classical markers.

Table D9. Study results for reticulocyte hemoglobin equivalent (RetHe)—iron status as defined by classical laboratory markers.

Table D9

Study results for reticulocyte hemoglobin equivalent (RetHe)—iron status as defined by classical laboratory markers.

One cross-sectional study evaluated the test performance of RetHe for assessing iron status in 19 PD CKD and 84 ND CKD patients, separately.11 The test agreement between RetHe and classical markers of iron status was poor. However, had a potential for selection bias, an unclear description of the study population (including how 85 samples were drawn from 19 patients), and a bias in results due to nonadjustment for within-patient correlation.

Soluble Transferrin Receptor

Key Points

Four cross-sectional studies, enrolling a total of 325 adult HD CKD patients,5,12,13,19 and 1 cross-sectional study with 27 pediatric HD and PD CKD patients10 evaluated the test performance of sTfR for assessing iron status as defined by classical laboratory markers. Of these studies, two were rated as being at a medium risk of bias, and three at a high risk of bias. Four studies enrolled primarily older HD CKD patients (mean age ranged from 43 to 62 years old), and one study enrolled 11 pediatric HD CKD patients (mean age 16 years old) and 16 pediatric PD CKD patients (mean age 13 years old). Baseline iron status, based on mean serum ferritin and TSTA concentrations, varied across studies.

Overall, sTfR and classical laboratory markers (TSAT or ferritin) have poor to fair agreements for assessing iron status in adult HD CKD patients.

Detailed Synthesis

(Table D10 to D12)

Four cross-sectional studies, enrolling a total of 325 adult HD CKD patients,5,12,13,19 and 1 cross-sectional study with 27 pediatric HD and PD CKD patients10 evaluated the test performance of sTfR for assessing iron status as defined by classical laboratory markers. Studies were conducted in different countries: Belgium, Italy, India, Japan, and Germany. Four studies enrolled primarily older HD CKD patients (mean age ranged from 43 to 62 years old),5,12,13,19 and one study enrolled 11 pediatric HD CKD patients (mean age 16 years old) and 16 pediatric PD CKD patients (mean age 13 years old).10 One study did not report any information on background treatment or patients’ anemia or iron status.13 In the other four studies, baseline mean Hb concentrations ranged from 10.2 to 11.5 g/dL. One of the four studies reported a mean ferritin concentration less than 100 ng/mL (indicating an insufficient iron store status),19 while the other three reported a mean ferritin concentration greater than 100 ng/mL at baseline (ranging from 124 to 353 ng/mL).5,10,12,13 Patients in two studies received maintenance ESA treatment,12,19 while the other three5,10,13 did not report information on background ESA treatment (Table D10).

Table D10. Characteristics of studies evaluating the test performance of soluble transferring receptor (sTfR) for assessing iron status as defined by classical laboratory markers.

Table D10

Characteristics of studies evaluating the test performance of soluble transferring receptor (sTfR) for assessing iron status as defined by classical laboratory markers.

The test performance of sTfR was assessed using three different reference standards of iron status (as defined by classical laboratory markers): 1) TSAT <20% and ferritin <100 ng/mL;12,13,19 2) TSAT <20%;5,12 and 3) TSAT <16% and ferritin <12 ng/mL.13 Studies used variable CHr cutoffs to define iron deficiency: >1.5 mg/L, > 3.05 nmol/L, >8.5 mg/L, and >28 nmol/L (pediatric CKD). One study analyzed the test performance of sTfR as a continuous measure.19

The reported sensitivity and specificity pairs at different sTfR cutoffs, as well as the estimated agreements between sTfR and classical markers of iron status, are summarized in Tables D11 and D12. Among adult HD CKD patients, three studies showed poor to fair test agreements between sTfR and classical markers of iron status.5,12,13 Another study performed multivariate analyses and showed that sTfR remained a significant predictor among other markers (including hematocrit, CHr, %HYPO, log ferritin, and epoetin user status). The multivariate analyses also showed that each 0.1 mg/mL increase in sTfR and one standard deviation increase (equivalent to 4.28 mg/L) in sTfR were associated with a respective 1.88 (95 percent CI, 1.29 to 2.53) and 1.69 (95 percent CI, 1.03 to 2.76) fold increase in the odds of iron deficiency (defined as TSAT < 20 percent).19 However, CHr was the strongest predictor in this multivariate model.

Table D11. Summary of results for the test agreements between soluble transferring receptor (sTfR) and classical markers.

Table D11

Summary of results for the test agreements between soluble transferring receptor (sTfR) and classical markers.

Table D12. Study results for soluble transferring receptor (sTfR)—iron status as defined by classical laboratory markers.

Table D12

Study results for soluble transferring receptor (sTfR)—iron status as defined by classical laboratory markers.

Among pediatric CKD patients, one cross-sectional study with a total of 16 pediatric PD CKD patients and 11 pediatric HD CKD patients evaluated the test performance of sTfR for assessing iron status.10 The test agreement between sTfR (a cutoff of > 28 nM/L to define iron deficiency) and classical laboratory markers of iron deficiency (TSAT < 20% and ferritin <100 ng/mL) was poor and of large uncertainty (wide confidence interval) due to small sample size.

Erythrocyte Zinc Protoporphyrin

Key Points

Two cross-sectional studies, enrolling a total of 281 adult HD CKD patients5,17 evaluated the test performance of CHr for assessing iron status as defined by classical laboratory markers. Of these studies, one was rated as being at a medium risk of bias, and the other at a high risk of bias. Studies enrolled primarily older patients with sufficient iron store (based on mean serum ferritin concentration).

Overall, ZPP and classical laboratory markers (TSAT<20%) have poor to fair agreements for assessing iron status in HD CKD patients with normal iron store as indicated by mean serum ferritin concentrations >100 ng/mL.

Detailed Synthesis

(Table D13to D15)

Two cross-sectional studies, enrolling a total of 281 adult HD CKD patients, evaluated the test performance of CHR for assessing iron status as defined by classical laboratory markers. 5,17 These studies used a TSAT less than 20 percent to define ID. One study was conducted in Poland,17 and the other conducted in Belgium.5

Both studies enrolled primarily older men and women (mean age 61 years old; age range 18 to 75 years old). Baseline mean Hb concentrations were 10.2 and 8.8 g/d. Both studies reported a mean ferritin concentration greater than 100 ng/mL at baseline (353 and 274 ng/mL, respectively). Reported baseline mean TSATs were 24 to 38 percent, respectively. Both studies reported different background treatments (Table D13).

Table D13. Characteristics of cross-sectional studies evaluating the test performance of erythrocyte zinc protoporphyrin (ZPP) for assessing iron status as defined by classical laboratory markers.

Table D13

Characteristics of cross-sectional studies evaluating the test performance of erythrocyte zinc protoporphyrin (ZPP) for assessing iron status as defined by classical laboratory markers.

Both studies assessed the test performance of ZPP using TSAT <20% as the reference standard of iron status. The reported sensitivity and specificity pairs at different ZPP cutoffs, as well as the estimated agreements between CHr and classical markers of iron status are summarized in Tables D14 and D15. The studies showed poor to fair test agreements between ZPP and TSAT, and there were consistent threshold effects across studies. Higher ZPP cutoffs were associated with better agreements with TSAT <20%. One study also assessed the test performance of ZPP to log ferritin index ratio for assessing iron deficiency as defined by TSAT <20%. The reported sensitivity and specificity pairs for ZPP to log ferritin index ≥40 were 76% and 83%, respectively, and the sensitivity and specificity pairs for ZPP to log ferritin index ≥45 were 72% and 86%, respectively.17

Table D14. Summary of results for the test agreements between erythrocyte zinc protoporphyrin (ZPP) and classical markers.

Table D14

Summary of results for the test agreements between erythrocyte zinc protoporphyrin (ZPP) and classical markers.

Table D15. Summary results for erythrocyte zinc protoporphyrin (ZPP)—iron status as defined by classical laboratory markers.

Table D15

Summary results for erythrocyte zinc protoporphyrin (ZPP)—iron status as defined by classical laboratory markers.

References

1.
Anaemia Management in Chronic Kidney Disease—Rapid Update 2011. National Clinical Guideline Centre; 2011. [PubMed: 22220322]
2.
Teutsch SM, Bradley LA, Palomaki GE, et al. The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Initiative: methods of the EGAPP Working Group. Genet Med. 2009 Jan;11(1):3–14. [PMC free article: PMC2743609] [PubMed: 18813139]
3.
Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977 Mar;33(1):159–74. [PubMed: 843571]
4.
Feuerman M, Miller AR. Relationships between statistical measures of agreement: sensitivity, specificity and kappa. J Eval Clin Pract. 2008 Oct;14(5):930–33. [PubMed: 19018927]
5.
Baldus M, Walter H, Thies K, et al. Transferrin receptor assay and zinc protoporphyrin as markers of iron-deficient erythropoiesis in end-stage renal disease patients. Clinical Nephrology. 1998 Mar;49(3):186–92. [PubMed: 9543601]
6.
Bhandari S, Norfolk D, Brownjohn A, et al. Evaluation of RBC ferritin and reticulocyte measurements in monitoring response to intravenous iron therapy. American Journal of Kidney Diseases. 1997 Dec;30(6):814–21. [PubMed: 9398126]
7.
Bhandari S, Turney JH, Brownjohn AM, et al. Reticulocyte indices in patients with end stage renal disease on hemodialysis. Journal of Nephrology. 1998 Mar;11(2):78–82. [PubMed: 9589378]
8.
Brugnara C, Schiller B, Moran J. Reticulocyte hemoglobin equivalent (Ret He) and assessment of iron-deficient states. Clinical & Laboratory Haematology. 2006 Oct;28(5):303–08. [PMC free article: PMC1618805] [PubMed: 16999719]
9.
Cullen P, Soffker J, Hopfl M, et al. Hypochromic red cells and reticulocyte haemglobin content as markers of iron-deficient erythropoiesis in patients undergoing chronic haemodialysis. Nephrology Dialysis Transplantation. 1999 Mar;14(3):659–65. [PubMed: 10193816]
10.
Daschner M, Mehls O, Schaefer F. Soluble transferrin receptor is correlated with erythropoietin sensitivity in dialysis patients. Clinical Nephrology. 1999 Oct;52(4):246–52. [PubMed: 10543327]
11.
Eguchi A, Tsuchiya K, Tsukada M, et al. [Clinical usefulness of reticulocyte hemoglobin equivalent (RET-He) in patients at the pre-dialysis stage and in patients on peritoneal dialysis]. Nippon Jinzo Gakkai Shi. 2010;(2):132–40. [Japanese] Japanese. [PubMed: 20415234]
12.
Fusaro M, Munaretto G, Spinello M, et al. Soluble transferrin receptors and reticulocyte hemoglobin concentration in the assessment of iron deficiency in hemodialysis patients. Journal of Nephrology. 2005 Jan;18(1):72–79. [PubMed: 15772926]
13.
Gupta M, Kannan M, Gupta S, et al. Contribution of iron deficiency to anemia in chronic renal failure. Indian Journal of Pathology & Microbiology. 2003 Oct;46(4):563–64. [PubMed: 15025343]
14.
Hukic F, Nuhbegovic S, Brkic S, et al. Biochemical markers of iron status in hemodialysis patients. Medicinski Arhiv. 2010;64(4):219–22. [PubMed: 21246919]
15.
Kaneko Y, Miyazaki S, Hirasawa Y, et al. Transferrin saturation versus reticulocyte hemoglobin content for iron deficiency in Japanese hemodialysis patients. Kidney International. 2003 Mar;63(3):1086–93. [PubMed: 12631092]
16.
Kim JM, Ihm CH, Kim HJ. Evaluation of reticulocyte haemoglobin content as marker of iron deficiency and predictor of response to intravenous iron in haemodialysis patients. International Journal of Laboratory Hematology. 2008 Feb;30(1):46–52. [PubMed: 18190467]
17.
Matuszkiewicz-Rowinska J, Ostrowski G, Niemczyk S, et al. [Red cell zinc protoporphyrin and its ratio to serum ferritin (ZPP/logSF index) in the detection of iron deficiency in patients with end-stage renal failure on hemodialysis]. Polskie Archiwum Medycyny Wewnetrznej. 2003 Jul;110(1):703–10. [Polish] [PubMed: 14682204]
18.
Miwa N, Akiba T, Kimata N, et al. Usefulness of measuring reticulocyte hemoglobin equivalent in the management of haemodialysis patients with iron deficiency. International Journal of Laboratory Hematology. 2010 Apr;32(2):248–55. [PubMed: 19624802]
19.
Tsuchiya K, Okano H, Teramura M, et al. Content of reticulocyte hemoglobin is a reliable tool for determining iron deficiency in dialysis patients. Clinical Nephrology. 2003 Feb;59(2):115–23. [PubMed: 12608554]
PubReader format: click here to try

Views

  • PubReader
  • Print View
  • Cite this Page
  • PDF version of this title (1.9M)

Related information

  • PMC
    PubMed Central citations
  • PubMed
    Links to pubmed

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...