Zinc Protoporphyrin Measurements Research Articles

A "One-Stop" Screening Protocol for Haemoglobinopathy Traits and Iron Deficiency in Sri Lanka.

Introduction: The high frequencies of carriers of severe haemoglobinopathies and of iron deficiency in Southeast Asia require reliable and affordable tests to improve on current screening procedures.Objectives: We evaluate a “one stop” approach using the THALCON dichlorophenolindophenol (DCIP) and one-tube osmotic fragility (OF) tests and measurement of Zinc Protoporphyrin (ZPP) to detect and distinguish HbE and β-thalassaemia traits from iron deficiency. We compare findings with current screening practice in Sri Lanka that relies on the identification of low mean red cell volume and/or mean red cell hemoglobin for this purpose.Methods: Between November 2017 and May 2018, we undertook a cross-sectional survey of secondary school students in Gampaha district, Sri Lanka. The THALCON–DCIP and OF tests were compared to capillary electrophoresis (CE), used as a gold standard to detect haemoglobinopathies. ZPP was measured in whole blood. Plasma ferritin and C-reactive protein (CRP) were measured in students with a raised ZPP concentration.Results: We collected venous blood samples from 1,324/1,332 (99.4%) students. The median age of the students was 17 (IQR 16–18) years, all were Sinhalese and 814/1,324 (61.5%) were female. CE identified 3 students with HbE trait and 26 students with β-thalassaemia trait. The THALCON–DCIP test was positive only in the 3 students with HbE (sensitivity 100%, 95% CI 29.2–100.0; specificity 100%, 95% CI 99.7–100.0). The THALCON–OF test identified all 26 students with β-thalassaemia trait (sensitivity = 100%, 95% CI 86.8–100.0) and 287 students with a normal CE result (specificity = 77.9%; 95% CI 75.5–80.1). It was also positive in 2/3 (66.7%) students with HbE trait. Iron deficiency (ZPP > 70 μmol/mol heme) was present in 118/1,240 (9.5%) students with a normal hemoglobin genotype, all of whom had plasma ferritin <15 ng/ml and CRP <5 mg/L.Conclusion: This one–stop approach offers reliable and affordable population screening for both haemoglobinopathy traits and iron deficiency in resource-limited settings where these conditions are common and ensures that iron supplements are targeted only to those who require them. Further work is warranted to refine the OF test to reduce the number of false positive results.

Lead and mercury exposure in populations on the banks of the Bogotá River: a multi-method study

This study sought to understand the health problems associated with the presence of lead and mercury in the water of the Bogotá River. A mixed methods study was conducted using interviews, surveys and measurements of zinc protoporphyrin (ZPP) and mercury in blood from 172 individuals. Variables associated with the highest concentrations were identified, as well as the attributes of the cases with increased exposure by means of a qualitative comparative analysis. Interviews reported that river pollution is associated with diseases, although direct exposure to water is rare. River water is widely used for irrigation of crops that are sold in other municipalities. Communities with greater exposure to river water are Tocaima and Girardot. The highest levels of ZPP were observed among those living in these municipalities, did activities at home and performed non-work activities using metals. Increased ZPP levels were associated with depression, nasal bleeding and loss of appetite. The highest concentrations of mercury were found in the inhabitants of Girardot, and were associated with sweating, disorientation, nausea and diarrhea. Low levels of lead and mercury were observed in the study population, although there are specific cases with high social vulnerability that require special attention.

Laboratory diagnosis of thalassemia.

The thalassemias can be defined as α- or β-thalassemias depending on the defective globin chain and on the underlying molecular defects. The recognition of carriers is possible by hematological tests. Both α- and β-thalassemia carriers (heterozygotes) present with microcytic hypochromic parameters with or without mild anemia. Red cell indices and morphology followed by separation and measurement of Hb fractions are the basis for identification of carriers. In addition, iron status should be ascertained by ferritin or zinc protoporphyrin measurements and the iron/total iron-binding capacity/saturation index. Mean corpuscular volume and mean corpuscular hemoglobin are markedly reduced (mean corpuscular volume: 60-70fl; MCH: 19-23pg) in β-thalassemia carriers, whereas a slight to relevant reduction is usually observed in α-carriers. HbA2 determination is the most decisive test for β-carrier detection although it can be disturbed by the presence of δ-thalassemia defects. In α-thalassemia, HbA2 can be lower than normal and it assumes significant value when iron deficiency is excluded. Several algorithms have been introduced to discriminate from thalassemia carriers and subjects with iron-deficient anemia; because the only discriminating parameter is the red cell counts, these formulas must be used consciously. Molecular analysis is not required to confirm the diagnosis of β-carrier, but it is necessary to confirm the α-thalassemia carrier status. The molecular diagnosis is essential to predict severe transfusion-dependent and intermediate-to-mild non-transfusion-dependent cases. DNA analysis on chorionic villi is the approach for prenatal diagnosis and the methods are the same used for mutations detection, according to the laboratory facilities and expertise.

High prevalence of subclinical iron deficiency in whole blood donors not deferred for low hemoglobin

Blood donors that meet the hemoglobin (Hb) criteria for donation may have undetected subclinical iron deficiency. The aim of this study was to assess the prevalence of subclinical iron deficiency in whole blood donors with Hb levels above cutoff levels for donation by measuring zinc protoporphyrin (ZPP) levels. In addition, prevalence rates based on other iron variables were assessed for comparison. The study population comprised 5280 Dutch whole blood donors, who passed the Hb criteria for donation. During donor screening, Hb levels were measured in capillary samples (finger prick), and venous blood samples were taken for measurements of ZPP and other iron variables. These variables included ferritin, transferrin saturation, soluble transferrin receptor (sTfR), hepcidin, red blood cell mean corpuscular volume (MCV), and mean cell Hb (MCH). With a ZPP cutoff level of at least 100 μmol/mol heme, subclinical iron deficiency was present in 6.9% of male donors and in 9.8% of female donors. Based on other iron variables, iron deficiency was also observed. Prevalence rates ranged from 4.8% (based on transferrin saturation) to 27.4% (based on hepcidin concentration) in men and from 5.6% (based on sTfR concentration) to 24.7% (based on hepcidin concentration) in women. Results from this study showed that subclinical iron deficiency is prevalent among blood donors that meet the Hb criteria for blood donation, based on ZPP levels and on other iron variables. This finding needs attention because these donors are at increased risk of developing iron deficiency affecting Hb formation and other cellular processes.

Zinc protoporphyrin levels have added value in the prediction of low hemoglobin deferral in whole blood donors

Increased zinc protoporphyrin (ZPP) levels can indicate iron deficiency and may be predictive for low hemoglobin (Hb) deferral in blood donors. Prediction models for Hb deferral in whole blood donors have already been developed. In this study, we examined if addition of ZPP to these prediction models improves risk estimation of Hb deferral. This study included 4598 Dutch whole blood donors. Information on ZPP levels measured at the previous visit was added to the existing prediction models to estimate the risk of Hb deferral. Models were compared using the following measures: concordance (c)-statistic, continuous net reclassification improvement (NRI), and clinical net benefit (NB). Seventy-six male donors (2.9%) and 69 female donors (3.5%) were deferred because of a low Hb level. Previous ZPP level was associated with risk of Hb deferral (odds ratio for interquartile range of previous ZPP level, men 2.0 [95% confidence interval {CI}, 1.7-2.3]; women 2.2 [95% CI, 1.9-2.4]) in a multivariable risk model. Addition of ZPP into the models resulted in an increase of the c-statistic from 0.93 to 0.94 for men and from 0.80 to 0.85 for women. The added value of ZPP was confirmed by measures of clinical usefulness. NRI for men was 0.42, and for women, 0.56. At relevant threshold probabilities between 10 and 15%, NB was higher for models considering ZPP. This study shows that ZPP measurements obtained at the previous visit may have added value in the risk prediction of Hb deferral in whole blood donors.

The interpretation of zinc protoporphyrin changes in lead intoxication: a case report and review of the literature

Zinc protoporphyrin (ZPP) has been used both as a screening and diagnostic test for overexposure to lead for nearly 30 years, although limitations for both purposes are recognized. We present longitudinal findings for ZPP and whole-blood lead in a man with two episodes of acute lead intoxication and review the literature on the use of ZPP. ZPP elevations in both chronic and acute exposure settings lag behind elevations in whole-blood lead by approximately 8-12 weeks. Therefore, ZPP measurement, in conjunction with whole-blood lead determination, has clinical utility in cases of substantial overexposure by providing information on how long an individual may have been overexposed to lead. A guide to the interpretation of various combinations of whole-blood lead and ZPP results is provided. However, while ZPP levels do correlate with whole-blood lead measurements in aggregate, the considerable individual variability of ZPP measurements, poor sensitivity at lower ranges of lead exposure, poor specificity and delayed changes in unstable exposure conditions indicate that this test contributes little to screening programs. Finally, our results confirm that basophilic stippling is seen in acute as well as chronic lead intoxication, and may provide the first indication of lead intoxication.

Erythrocyte zinc protoporphyrin testing in pregnancy

To compare the usefulness of serum ferritin, hemoglobin and erythrocyte zinc protoporphyrin estimations as indicators of the need of iron supplementation in pregnancy. In 97 healthy pregnant women serum ferritin, hemoglobin and erythrocyte zinc protoporphyrin concentrations were measured at each trimester period. Iron supplementation was prescribed at hemoglobin values below 113 g/L. Neither in the first nor in the second trimester differences in serum ferritin and erythrocyte zinc protoporphyrin values have been found between women who got iron therapy prescribed and women who did not get iron therapy, whereas already in the first trimester hemoglobin values were lower in the group that got iron therapy. These results indicate that hemodilution rather than iron deficiency determined which women got iron therapy. In the third trimester 14 out of 80 women without iron supplementation had depleted iron stores and a significant erythrocyte zinc protoporphyrin increase, indicating evolving iron deficiency anemia. However, only five of them showed hemoglobin levels below 113 g/L and got iron therapy. Low serum ferritin levels were found in 23% of the women at booking and in 92% in the third trimester. Serum ferritin levels neither predicted the development of iron deficient erythropoiesis nor of anemia. Iron deficiency can neither be diagnosed nor predicted by serum ferritin or hemoglobin measurements at booking or later on in pregnancy. Erythrocyte zinc protoporphyrin measurements can be of help in determining which women have iron deficient erythropoiesis and may benefit by iron therapy.

Lead intoxication epidemic caused by ingestion of contaminated ground paprika.

Report of a lead intoxication epidemic caused by ingestion of contaminated ground paprika. Retrospective study of case histories. Institutional, toxicological and medical referral center for ambulatory and hospitalized care. One hundred forty-one adults consumed paprika contaminated with lead tetroxide (red lead). Intravenous calcium disodium versenate (edetic acid). Measurement of zinc protoporphyrin:heme ratio of whole blood and the blood lead level. EDTA mobilization test. Fifty-three patients had symptoms and signs of lead poisoning. The most common clinical signs were colic and/or anemia. Twenty-six persons showed increased lead absorption without clinical symptoms and signs. Chelation therapy with calcium disodium versenate resulted in complete clinical recovery. Lead-contaminated ground paprika, not previously described as a cause of alimentary lead intoxication, may cause symptomatic poisoning.

Usefulness of red cell zinc protoporphyrin concentration in the investigation of microcytosis in children.

The clinical usefulness of the measurement of red cell zinc protoporphyrin (ZPP), an indicator of iron-deficient erythropoiesis, was assessed in a group of UK children undergoing investigation for red cell microcytosis. Of 213 children studied, 136 had increased ZPP values. Of these, 86 also had reduced iron stores as indicated by serum ferritin concentration. The 50 children with increased ZPP and normal ferritin values could be divided into two main groups. One group comprised 28 children who had evidence of coexistent infection or inflammatory disease. The other included 21 children who had beta-thalassemia trait (n = 19) or disease (n = 2). Among the 77 children with normal ZPP values, 22 had reduced serum ferritin concentrations and 45 did not, nor did they have evidence of beta-thalassemia. Microcytosis in some of these children could have been due to alpha-thalassemia trait. Measurement of ZPP is a simple, quick, and relatively cheap method of confirming the presence of iron-deficient erythropoiesis even when inflammation makes serum ferritin measurements unreliable. It is not as sensitive as the ferritin assay to the early stages of iron deficiency, and its specificity is reduced by the occurrence of raised values in most children with beta-thalassemia trait. Where there is microcytosis, normal values, together with normal hemoglobin A2 and serum ferritin concentrations, are likely to indicate alpha-thalassemia trait.

Central role of zinc protoporphyrin in staging iron deficiency

In iron deficiency, zinc protoporphyrin (ZPP) is produced instead of heme, and the ZPP concentration in erythrocytes is increased (normal < or = 40 mumol/mol heme). We investigated the relevance of ZPP for staging iron deficiency. ZPP was determined by hematofluorometry in samples from 103 patients. Nineteen patients with iron depletion showed decreased serum ferritin (12.1 +/- 4.4 micrograms/L) with normal ZPP and hemoglobin (Hb). Twelve patients with iron-deficient erythropoiesis had decreased ferritin (10.4 +/- 2.4 micrograms/L), increased ZPP (72 +/- 9 mumol/mol heme), and normal Hb concentrations. In 72 patients with iron-deficiency anemia, ferritin was < 12 micrograms/L. In mild anemia (Hb between 100 and 120 g/L, and normal erythrocyte indices), ZPP was 100 +/- 16 mumol/mol heme. In severe anemia (Hb < 100 g/L, decreased erythrocyte indices), ZPP values were significantly higher (265 +/- 109 mumol/mol heme). We conclude that measurements of ZPP, ferritin, and Hb can reliably be combined to classify the degree of iron deficiency.

The measurement of zinc protoporphyrin for iron deficiency anemia by hematofluorometer in children

Zinc protoporphyrin (ZPP) is generated in the erythrocytes of patients with lead toxication and iron deficiency anemia by the incorporation of zinc instead of ferrous iron into protoporphyrin. Although the measurement of ZPP has been thought to be a potential screening test for evaluating iron deficiency, no simple and reliable ZPP assay method has been available until recently. A newly developed hematofluorometer allows us to quickly determine the level of ZPP in a drop of unprocessed whole blood. In this study, we measured the concentration of ZPP in 732 children including 22 patients with iron deficiency anemia using this hematofluorometer. The cut off value of whole blood ZPP in children was determined to be 38.2 micrograms ZPP/dl whole blood. The level of ZPP showed a good negative correlation with the concentration of hemoglobin. The specificity and the sensitivity of this assay were 97.2% and 81.8%, respectively. These results indicate that this ZPP assay using the newly-developed hematofluorometer is a practical way to screen for iron deficiency anemia.

The effect of respiratory protection with biological monitoring on the health management of lead workers in a storage battery industry.

Respiratory protection with maintenance free respirator and regular biological monitoring with the measurement of zinc protoporphyrin for one year period not only made significant decreases of biological indices indicative of lead exposure (blood lead, delta-aminolevulinic acid in urine) in a storage battery workers, but also reduced the prevalence of lead related symptoms.

Washing Erythrocytes to Remove Interferents in Measurements of Zinc Protoporphyrin by Front-Face Hematofluorometry

Zinc protoporphyrin (ZPP) is determined by hematofluorometry of whole blood to detect iron deficiency in blood donors. In hospitalized patients, ZPP did not correlate with established markers of iron status. We performed 4500 ZPP measurements with the Aviv front-face hematofluorometer in samples from 475 patients and measured ferritin, transferrin saturation, hemoglobin, and erythrocyte indices. We found that the fluorometric determination is affected by substances dissolved in plasma but that this interference can be eliminated by using washed erythrocytes. In validation tests the within-day variation was < 3.5%; the day-to-day variation was < 6.8%. In 130 healthy persons without iron deficiency, ZPP was < or = 40 mumol/mol heme, which we consider a normal value. Mean ZPP in 46 iron-deficient patients was 256 (SD 105) mumol/mol heme (correlation with ferritin: -0.73; with hemoglobin: -0.85; P < 0.001). When washed erythrocytes are used, the hematofluorometric determination of ZPP is sensitive and specific for detecting iron deficiency in otherwise healthy individuals and hospitalized patients.

Measurement of zinc protoporphyrin with the ProtoFluor-Z System

Journal Article Measurement of zinc protoporphyrin with the ProtoFluor-Z System Get access R F Labbé, R F Labbé Search for other works by this author on: Oxford Academic Google Scholar R L Rettmer R L Rettmer Search for other works by this author on: Oxford Academic Google Scholar Clinical Chemistry, Volume 36, Issue 4, 1 April 1990, Pages 702–703, https://doi.org/10.1093/clinchem/36.4.702 Published: 01 April 1990

Zinc Protoporphyrin Past, Present, and Futurea

The course of zinc protoporphyrin research has progressed at an increasingly rapid pace on several fronts. A variety of biochemical and clinical evidence viewed in toto now suggests that ferrochelatase catalyzes zinc protoporphyrin formation in states of relative iron-deficient erythropoiesis and in lead-inhibited iron metabolism. Furthermore, a redefinition of the relationship of zinc protoporphyrin to certain other parameters of iron status has been made based upon changes during the earliest states of iron depletion. These clinical studies show that the zinc protoporphyrin level and the ferritin level vary in concert but that changes in the percent transferrin saturation and in the hematocrit results are less consistent. Thus zinc protoporphyrin and ferritin are closely linked metabolically such that iron-deficient erythropoiesis becomes an initial manifestation of iron depletion. The measurement and expression of results as mumoles zinc protoporphyrin/mole heme have improved the quality of results, partly by the elimination of the assumed hematocrit designed into existing instruments. Other refinements in hematofluorometry technology have permitted exploration of the potentially extensive applications of zinc protoporphyrin measurements for lead surveillance and diagnosis, blood banking, pediatrics, obstetrics, sports medicine, and other clinical situations where a very sensitive, cost-effective indication of iron status is required.

Zinc protoporphyrin as an indicator of lead exposure: precision of zinc protoporphyrin measurements.

In lead-exposed workers many factors affect the relationship between the levels of lead and of zinc protoporphyrin (ZPP) in blood. When the zinc protoporphyrin level is used to assess the lead in the blood level, the analytical accuracy of the ZPP and the PbB determinations should be known. Also the variability of lead exposure over time is an important parameter of this assessment. The absolute and relative precision of ZPP measurements with two brands of ZPP meters (AVIV and ESA) were compared. The absolute precision of the ZPP measurements is not constant for the AVIV meter, but is constant for the ESA meter. The relative precision for both brands of meters decreases with increasing ZPP levels. Between the AVIV and the ESA meters, a significant difference in response, irrespective of the kind of anticoagulant used, was observed. The regression equations between PbB and ZPP levels were studied. Different factors can affect the relationship between PbB and ZPP, e.g. variability in lead exposure, the time-lag between the increase of PbB and ZPP, and the precision and accuracy of PbB and ZPP measurements.

Red blood cell zinc protoporphyrin testing for iron-deficiency anemia in pregnancy

The diagnostic value of ferritin, transferrin saturation, and red blood cell zinc protoporphyrin for detecting iron depletion and predicting third-trimester anemia was studied in 87 women attending a private obstetrics clinic. A decline in ferritin and transferrin saturation and an increase in red blood cell zinc protoporphyrin levels were observed in third-trimester measurements when compared with those of the first trimester. Third-trimester anemia (hemoglobin less than 11.5 gm/dl or 115 gm/L) was detected in 13 (15%) women. Red blood cell zinc protoporphyrin was the only test that consistently demonstrated significantly different mean values between anemic and normal subgroups. The diagnostic sensitivity and predictive value of red blood cell zinc protoporphyrin for evaluating iron depletion and risk of anemia in pregnancy compared favorably to those of ferritin and transferrin saturation measurements. The operational simplicity and low cost of red blood cell zinc protoporphyrin measurements are additional characteristics that favor this procedure for office testing.

Monitoring of zinc protoporphyrin levels in blood following occupational lead exposure.

The value of measurements of zinc protoporphyrin in blood (ZPP) in the surveillance of workers occupationally exposed to lead has been studied. From a group of referents, consisting of 1,088 men and 511 women, it has been established that the normal mean ZPP is in the region of 25 micrograms/100 ml, and only rarely do values exceed 45 micrograms/100 ml. The higher ZPP values are frequently associated with low blood hemoglobin concentrations and appear to be manifestations of an iron-deficiency anemia. Women have higher ZPP values than men; smoking has no influence. Measurements of ZPP and blood lead concentration (PbB) have been made every other month for 2.5 years on a group of around 200 men and 40 women exposed to lead in a storage battery factory. The mean ZPP of the group throughout the period was 70.9 micrograms/100 ml blood, and a linear relation between log ZPP and PbB in the PbB range of 10-80 micrograms/100 ml has been established. ZPP thresholds in the control of excessive occupational lead exposure, and the economic advantage of ZPP measurements over PbB, are discussed.

Effects of iron deficiency and chronic iron overloading on mitochondrial heme biosynthetic enzymes in rat liver

The effects of iron deficiency and iron overloading on the mitochondrial enzymes involved in heme synthesis were studied in rat livers. The in vitro activities of several of the enzymes in this pathway were differentially influenced by the in vivo iron status of the animals. δ-Aminolevulinic acid synthase was slightly increased in iron-overloaded animals, but remained normal in iron-deficient animals (0.58 ± 0.09, 0.91 ± 0.19 and 0.61 ± 0.12 nmol δ-aminolevulinic acid/mg per h). Copro- and protoporphyrinogen oxidase activities were increased (20 and 60% above controls) in iron-deficient animals. In contrast, coproporphyrinogen oxidase was decreased by 20%, while protoporphyrinogen oxidase remained unchanged in iron-overloaded rats. These variations of activities were not due to changes in the affinity of these enzymes toward their substrates, as coporphyrinogen had the same Km in each case (0.62 ± 0.05 M) as did protoporphyrinogen (0.22 ± 0.035 M). Thus, the Km did not vary with the treatment received by the animals. Ferrochelatase activity was measured by both the pyridine hemochromogen method and by measurement of zinc protoporphyrin with endogenous zinc as substrate. In all cases, ferrochelatase was found to be able to synthesize zinc protoporphyrin with endogenous zinc as substrate. However, the apparent Km of zinc chelatase for protoporphyrin was significantly different in the three groups of animals with Km,appProto = 2.4 ± 0.1 10−7, 4 ± 0.3 10−7 and 9.10 ± 0.05 10−7 M in iron-overloaded, control and iron-deficient animals, respectively. When ferrochelatase activity was measured by pyridine hemochromogen, identical results were observed in iron-deficient and control animals but decreased by 45% in iron-overloaded animals. The mitochondrial heme content was also decreased by 40% in iron-overloaded rats but unchanged in either iron-deficient or control rats.

Free erythrocyte protoporphyrin and zinc protoporphyrin measurements compared as primary screening methods for detection of lead poisoning.

We compared two commonly used primary screening methods (FEP and ZnP) for detecting Pb poisoning in children, used according to three major protocols. The results showed that FEP and ZnP values were comparable for only 36% of the children examined; 54% had FEP greater than ZnP and 10% had ZnP greater than FEP. One would identify approximately twice as many children with Pb greater than 300 micrograms/L by an FEP (500 micrograms/L cutoff) as with a ZnP (400 micrograms/L cutoff) screen. With a cutoff of 350, as compared with 500 micrograms/L for ZnP, one would perform 33% additional confirmatory blood Pb determinations with a 3% increased detection of Pb intoxication. If the number of false-negative Pb specimens is to be minimized, the cutoff "action level" for hematofluorometers should be lowered from the currently recommended 500 micrograms/L of whole blood to 350 micrograms/L. Our long experience and that of other laboratories leads us to recommend a revision of Centers for Disease Control risk categories and cutoff values, depending on whether FEP or ZnP is measured in combination with a patient's blood Pb concentration. Our finding of above-normal values for ZnP and FEP with Pb concentrations less than 300 micrograms/L indicates that iron deficiency constitutes an equally important public-health problem for children in New York City.