Elevated Erythrocyte Protoporphyrin Research Articles

Attenti al sole e pensa al fegato: due casi pediatrici di protoporfiria eritropoietica

The article reports two cases of a rare paediatric disease: erythropoietic protoporphyria (EPP) characterized by burning erythema and variable liver damage. EPP is the most common porphyria in children, caused by mutations in ferrochelatase (FECH) gene, which is the last enzyme along the haem biosynthetic pathway. Consequently, haem precursor protoporphyrin IX accumulates in erythrocytes, plasma, skin and liver. The clinical features are: photosensitivity (pain, itching, burning along with oedema and/or erythema in sun-exposed areas), mild anaemia, and a variable degree of hepato-biliary disease with potential cholelithiasis and, in 1-5% of patients, end-stage liver disease. Diagnosis is made by finding elevated erythrocyte protoporphyrin and confirmed by molecular genetic testing in FECH gene. Therapy is based on sun protection, vitamin D, and beta-carotene, along with ursodeoxycholic acid and/or cholestyramine if hepatobiliary disease is present. Afamelanotide and cimetidine have shown efficacy in treating photo-sensitivity, but do not prevent liver damage, so that a tight follow-up is needed.

Leukocytoclastic vasculitis masking chronic vascular changes in previously undiagnosed erythropoietic protoporphyria

A 31-year old man presented with swelling and purpura of the dorsum of the hands following sun exposure. There was a preceding lifelong history of photosensitivity, but this episode, which occurred after the recent commencement of oral iron therapy, and after recent alcohol ingestion, was much more severe than any preceding episode. Skin biopsy performed 48 h after the onset of symptoms showed features consistent with the early stages of leukocytoclastic vasculitis. Direct immunofluorescence showed homogeneous thick staining of the vessel walls with IgG, IgM and IgA, together with abundant perivascular fibrinogen. A subsequent periodic acid-Schiff (PAS) stain on the skin biopsy revealed thickening of the walls of dermal vessels, which was not discernible in routinely stained (hematoxylin/eosin) sections. The diagnosis of erythropoietic protoporphyria (EPP) was confirmed by significantly elevated erythrocyte protoporphyrin levels and positive plasma fluorimetry. The diagnosis of porphyria may have been missed by routine skin microscopy if not for the additional information provided by clinical history, direct immunofluorescence and PAS stain. The pathogenesis and histopathology of acute and chronic vascular changes in EPP are reviewed.

Loss-of-Function Ferrochelatase and Gain-of-Function Erythroid-Specific 5-Aminolevulinate Synthase Mutations Causing Erythropoietic Protoporphyria and X-Linked Protoporphyria in North American Patients Reveal Novel Mutations and a High Prevalence of X-Linked Protoporphyria

Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) are inborn errors of heme biosynthesis with the same phenotype but resulting from autosomal recessive loss-of-function mutations in the ferrochelatase (FECH) gene and gain-of-function mutations in the X-linked erythroid-specific 5-aminolevulinate synthase (ALAS2) gene, respectively. The EPP phenotype is characterized by acute, painful, cutaneous photosensitivity and elevated erythrocyte protoporphyrin levels. We report the FECH and ALAS2 mutations in 155 unrelated North American patients with the EPP phenotype. FECH sequencing and dosage analyses identified 140 patients with EPP: 134 with one loss-of-function allele and the common IVS3-48T>C low expression allele, three with two loss-of-function mutations and three with one loss-of-function mutation and two low expression alleles. There were 48 previously reported and 23 novel FECH mutations. The remaining 15 probands had ALAS2 gain-of-function mutations causing XLP: 13 with the previously reported deletion, c.1706_1709delAGTG, and two with novel mutations, c.1734delG and c.1642C>T(p.Q548X). Notably, XLP represented ~10% of EPP phenotype patients in North America, two to five times more than in Western Europe. XLP males had twofold higher erythrocyte protoporphyrin levels than EPP patients, predisposing to more severe photosensitivity and liver disease. Identification of XLP patients permits accurate diagnosis and counseling of at-risk relatives and asymptomatic heterozygotes.

Erythropoetic protoporphyria presenting as “solar urticaria”

Rationale We describe a case of a 6-year old male initially diagnosed with solar urticaria but found to have a genetically based disorder of heme synthesis. Methods The patient presented with a 3-year history of a photosensative dermatosis which occurred during each summer season. He routinely developed pruritic, erythematous, and indurated skin eruptions to the face and arms within minutes of sun exposure. The lesions were not responsive to anti-histamine therapy and would remit within 48 hours. Past medical history was only significant for allergic rhinitis. Family history was significant for a similar rash to sun exposed areas in the mother and allergic rhinitis in the father. Results On exam there was evidence of dermal xerosis, hyperpigmentation and cicatrix formation over the face and hands. No significant lymphadenopathy or hepato-splenomegaly. Laboratory evaluation revealed a mild normochromic normocytic anemia (Hgb=11.2 g/dL), normal ESR and urinalysis, elevated total bilirubin (1.7 mg/dL), and a highly elevated erythrocyte protoporphyrin (>350 ug/dL). An autoimmune screen and 24- hour urine for porphyrin, porphobilinogen and delta-aminolevulinic acid were all negative. Conclusion Erythropoetic Protoporphyria was diagnosed in view of the clinical history and strong laboratory evidence. He had an excellent clinical response to treatment with oral beta-carotene, daily sunscreen, and topical zinc oxide. In summary, this is a young atopic male with porphyria who was originally diagnosed as having sun induced urticaria. As solar urticaria is a rare disorder, especially in children, suspected cases should be carefully assessed to rule out a rheumatologic or metabolic cause for their condition.

Hookworms, Malaria and Vitamin A Deficiency Contribute to Anemia and Iron Deficiency among Pregnant Women in the Plains of Nepal

Anemia and iron deficiency during pregnancy are prevalent in developing countries, but their causes are not always known. We assessed the prevalence and severity of anemia and iron deficiency and their association with helminths, malaria and vitamin A deficiency in a community-based sample of 336 pregnant women in the plains of Nepal. Hemoglobin, erythrocyte protoporphyrin (EP) and serum ferritin were assessed in venous blood samples. Overall, 72.6% of women were anemic (hemoglobin < 110 g/L), 19.9% had moderate to severe anemia (hemoglobin < 90 g/L) and 80.6% had iron deficiency (EP > 70 micromol/mol heme or serum ferritin < 10 microg/L). Eighty-eight percent of cases of anemia were associated with iron deficiency. More than half of the women (54.2%) had a low serum retinol concentration (<1.05 micromol/L), 74.2% were infected with hookworms and 19.8% had Plasmodium vivax malaria parasitemia. Hemoglobin, EP and serum ferritin concentrations were significantly worse and the prevalence of anemia, elevated EP and low serum ferritin was increased with increasing intensity of hookworm infection. Hookworm infection intensity was the strongest predictor of iron status, especially of depleted iron stores. Low serum retinol was most strongly associated with mild anemia, whereas P. vivax malaria and hookworm infection intensity were stronger predictors of moderate to severe anemia. These findings reinforce the need for programs to consider reducing the prevalence of hookworm, malaria infection and vitamin A deficiency where indicated, in addition to providing iron supplements to effectively control anemia.

Iron Deficiency Is a More Important Cause of Anemia than Hemoglobinopathies in Kuwaiti Adolescent Girls

Anemia is the most prevalent nutritional problem worldwide, due mainly to iron deficiency. Studies of anemia are less common in adolescents than in women and children. We examined anemia prevalence in adolescent Kuwaiti schoolgirls, and its association with hemoglobinopathies as well as the most common environmental cause, Fe deficiency. A cross-sectional sample of 1051 healthy adolescent schoolgirls was studied. Sample size was based on WHO criteria. Anemia, Fe deficiency and hemoglobin (Hb) variations were studied by Hb concentration, erythrocyte protoporphyrin (EP) and an HPLC quantitation, respectively. Of the subjects sampled, 30% were anemic. Mildly elevated EP values were found in 68%. Girls with high EP levels were more likely (P < 0.001) to be anemic than girls with normal EP. Up to 25% of the girls may have had Fe deficiency anemia. Hemoglobinopathies were neither prevalent nor significantly associated with anemia. These data indicate that environmental factors play a significant role in anemia among healthy, well-to-do Kuwaiti adolescent girls.

Children with Moderately Elevated Blood Lead Levels: A Role for Other Diagnostic Tests?

In this study we examined potential limitations of relying exclusively on blood lead (BPb) levels to evaluate children with moderately elevated BPb levels (1.21-2.12 micromol/l, or 25-44 microg/dl).We tested the following hypotheses: 1) such children without elevated erythrocyte protoporphyrin (EP) levels (&gt;=0.62 micromol/l or &gt;/= 35 microg/dl) are unlikely to respond to a chelating agent with a brisk urinary Pb diuresis; 2) those with elevated EP levels, but low hematologic indices consistent with iron deficiency, are also unlikely to respond to a chelating agent with a robust urinary Pb diuresis; and 3) those with elevated EP levels and iron sufficiency are more likely to respond to a chelating agent. To test these hypotheses, we performed retrospective analyses of the relationships between EP concentrations, hematologic indices, and urinary Pb excretion ratios (uPbr) in moderately Pb-poisoned children undergoing the CaNa2EDTA lead mobilization test (Pb-MT). Data from 122 children were available. Urinary Pb excretion was limited in children with an EP &lt;0.62 micromol/l (&lt;35 microg/dl); only 5% (1/21) of Pb-MTs were positive (uPbr &gt;=0.6). In children with an EP &gt;=0.62 micromol/l, low hematologic indices, such as a mean corpuscular hemoglobin (MCH) &lt;23 pg, were associated with relatively little Pb excretion (0/14 positive Pb-MTs). In contrast, 32% (28/87) of Pb-MTs were positive in children with an EP &gt;/= 0.62 micromol/l and iron sufficiency (p&lt;0.01 by chi-square comparison between groups with EP &gt;/= 0.62 micromol/l and either MCH &lt;23 pg or MCH &gt;/= 23 pg). We conclude that only a minority of moderately Pb-poisoned children will demonstrate enhanced urinary Pb excretion in response to chelation therapy. Some of the predicted nonresponders can be readily identified by adding the EP and complete blood count to the panel of tests performed.

Children with moderately elevated blood lead levels: a role for other diagnostic tests?

In this study we examined potential limitations of relying exclusively on blood lead (BPb) levels to evaluate children with moderately elevated BPb levels (1.21-2.12 micromol/l, or 25-44 microg/dl). We tested the following hypotheses: 1) such children without elevated erythrocyte protoporphyrin (EP) levels (>=0.62 micromol/l or >/= 35 microg/dl) are unlikely to respond to a chelating agent with a brisk urinary Pb diuresis; 2) those with elevated EP levels, but low hematologic indices consistent with iron deficiency, are also unlikely to respond to a chelating agent with a robust urinary Pb diuresis; and 3) those with elevated EP levels and iron sufficiency are more likely to respond to a chelating agent. To test these hypotheses, we performed retrospective analyses of the relationships between EP concentrations, hematologic indices, and urinary Pb excretion ratios (uPbr) in moderately Pb-poisoned children undergoing the CaNa2EDTA lead mobilization test (Pb-MT). Data from 122 children were available. Urinary Pb excretion was limited in children with an EP <0.62 micromol/l (<35 microg/dl); only 5% (1/21) of Pb-MTs were positive (uPbr >=0.6). In children with an EP >=0.62 micromol/l, low hematologic indices, such as a mean corpuscular hemoglobin (MCH) <23 pg, were associated with relatively little Pb excretion (0/14 positive Pb-MTs). In contrast, 32% (28/87) of Pb-MTs were positive in children with an EP >/= 0.62 micromol/l and iron sufficiency (p<0.01 by chi-square comparison between groups with EP >/= 0.62 micromol/l and either MCH <23 pg or MCH >/= 23 pg). We conclude that only a minority of moderately Pb-poisoned children will demonstrate enhanced urinary Pb excretion in response to chelation therapy. Some of the predicted nonresponders can be readily identified by adding the EP and complete blood count to the panel of tests performed.

A novel splicing mutation in the ferrochelatase gene responsible for erythropoietic protoporphyria

An aberrant ferrochelatase mRNA lacking exon 7 was found in a patient with erythropoietic protoporphyria (EPP). The exon 7 skipping appears to result from a G⪢A transition at position +5 of the donor site of intron 7 of the ferrochelatase gene. The patient is heterozygous for the mutation. Since the patient's paternal half-brother (not available for testing) also has clinically obvious EPP, their father appeared to be the source of the mutant allele. The father was in fact found to be a carrier of the same mutation and his ferrochelatase activity was 35% of normal; however, he is asymptomatic, with only a slightly elevated erythrocyte protoporphyrin level. These findings confirm that the observed mutation is responsible for the defect. The variability in clinical expression of EPP probably reflects the great heterogeneity of the ferrochelatase gene defects and the contribution of additional exogenous and endogenous inducers of latent disease.

Status of Immunization and Iron Nutrition in New York City Homeless Children

A retrospective review of the hospital records of New York City children aged 6 months through 6 years showed that 63 homeless children had a higher rate of immunization delay than an age- and sex-stratified sample of 63 domiciled children living at the same federal poverty level. In a logistic regression model, this difference persisted after controlling for sex, age, ethnicity, presence of chronic illness, and reason for referral. In a 6-month- to 2-year-old subgroup, homeless and domiciled children had equal rates of anemia, but homeless children were more likely to have elevated erythrocyte protoporphyrin (EP) levels consistent with iron deficiency. This difference, too, persisted after controlling for the same confounding factors. Elevated EP levels and immunization delay were likely to coexist in the homeless children. The higher rate of immunization delay is compatible with the occurrence of measles outbreaks in some New York City shelters. The higher rates of iron deficiency may reflect overall poor nutrition. All these findings have significant implications for the design of health-care programs for homeless children.

A risk assessment for selected lead-induced health effects: an example of a general methodology.

The research described here is part of a larger risk assessment project to aid the U.S. Environmental Protection Agency (EPA) in its review of the primary National Ambient Air Quality Standard for lead. The methodology can be applied to many situations in which a policy decision about a toxic substance is required in the face of incomplete data. Numerical results are presented for three potentially adverse lead-induced effects of interest to EPA: elevated erythrocyte protoporphyrin (EP), hemoglobin (Hb) decrement, and intelligence quotient (IQ) decrement.

Erythrocyte Protoporphyrin Screening for Lead Poisoning in Bedouin Children. A Study from Kuwait

Screening for lead poisoning can be performed by measuring either blood lead (PbB) or a haematological indicator such as erythrocyte protoporphyrin (EP). We have screened 902 infants and children aged from 3 months to 5 years amongst those attending three primary health care centres in AI Jahra governorate of Kuwait. Blood specimens were collected by finger prick on Guthrie filter paper and the dried blood samples were mailed to the Central Laboratory of the Children's Hospital, Buffalo, USA. One hundred and eighty-four (20 per cent) had an elevated EP (greater than 50 micrograms/dl). Of those 11 had values above 159 micrograms/dl; 140 children were further tested for blood lead levels (PbB) haemoglobin, mean cell volumes, and percentage of transferrin saturation; 41 had blood lead levels greater than 25 micrograms/dl which is the current definition of elevated blood lead levels. Two children (2 per cent) were in Class IV, 17 (15 per cent) and 16 (14 per cent) were in Class II and Class III, respectively. There was a significant correlation between EP and PbB (r = 0.686; P = less than 0.001). Of 72 children with elevated EP and normal PbB, 32 were anaemic (Hb less than 11 g/dl) and 20 had iron deficiency. The role of tribal practices using lead contaminated preparations and their contribution to elevated blood lead levels is discussed.

Ethnic group differences in nutritional status of young children from low-income areas of an urban county

A nutrition assessment survey was undertaken among 566 preschool children from randomly selected low income households located within an urban county. The purpose of the survey was to determine the prevalence of selected nutrition problems and to identify relationships among ethnic and economic variables and nutritional status. Underweight was identified in 1.8%, overweight in 15.4%, and short stature in 13.1% of children. Southeast Asian children had a higher prevalence of short stature than the other ethnic groups. Low hemoglobin values were identified in 4.3%, low hematocrit in 6.9%, and elevated erythrocyte protoporphyrin in 6.0% of children. The prevalence of elevated EP was significantly higher among Southeast Asian children than non-Southeast Asians and likely was due to iron deficiency. Results of the survey suggest that Southeast Asian children constitute the group at highest nutritional risk in the low income areas surveyed.

Porphyrin photosensitization and phototherapy.

Porphyrin photosensitization and phototherapy.

Occurrence of elevated protoporphyrin levels in relation to lead burden in infants

Simultaneous blood lead (PbB), erythrocyte protoporphyrin (EP), and hematocrit measurements were made semiannually in 232 normal infants from 6 to 24 months of age. The PbB averaged 7 (SD = 5) and ranged from 0 to 64 micrograms/dl. The incidence of elevated EP, a marker for deranged heme synthesis, was unrelated to PbB at levels below 15 micrograms/dl but was fourfold greater among the infants with PbB above 15 micrograms/dl. This relationship persisted even after eliminating the 31 (4%) anemic (hematocrit less than 33%) samples. The confounding effects of iron deficiency are discussed.

High incidence of lead poisoning revealed by erythrocyte protoporphyrin (EPP) screening in Arabian children

The measurement of erythrocyte protoporphyrin (EPP) has been used in screening infants for undue exposure to lead. The infants were from a high risk area, Al Jahra in Kuwait, and were selected from those attending the emergency department of Al Jahra District Hospital. Dried spots of blood on Guthrie filter paper were mailed to the Central Laboratory of the Children's Hospital in Buffalo, New York. Elevated EPP values (greater than 50 micrograms/dl) were present in 63 (66%) out of 96 tests. Forty-four of the infants with elevated values were investigated further: 16 had blood lead levels above 30 micrograms/dl (1.45 mmol/l) and 12 had evidence of iron deficiency anaemia. Five infants with blood lead levels above 80 micrograms/dl (3.9 mmol/l) needed urgent chelation and in addition an 8-month-old infant with the highest EPP value (478 micrograms/dl) died of acute lead encephalopathy. We conclude that lead poisoning is a serious problem in Al Jahra, Kuwait, and that a comprehensive programme for screening and health education are urgently needed to avoid the irreversible effects of lead toxicity.

Increased red blood cell protoporphyrin in thalassemia: a result of relative iron deficiency.

Erythrocyte protoporphyrin (EP) was measured in 50 normal control subjects, 22 iron-responsive anemic subjects, and in 106 patients with thalassemic diseases. All normal subjects had EP of less than 80 micrograms/dL red blood cells, whereas all iron-deficiency subjects had EP of more than 80 micrograms/dL red blood cells. Six of 22 heterozygotes for thalassemias had elevated EP, and all of these had transferrin iron saturation of less than 16%, reflecting a complicating iron deficiency. Among 52 patients with beta-thalassemia/hemoglobin (Hb) E disease, 26.9% had elevated EP levels, and among 32 patients with Hb H disease, 40.6% had elevated EP. These elevated EP levels were associated with transferrin iron saturation between 18 and 44%. In none of the thalassemic patients with transferrin iron saturation above 44% was EP elevated. These findings suggest that elevation of EP in some thalassemic patients causally is related to iron supply inadequate for the massively expanded erythropoiesis. This relative iron deficiency in thalassemia occurs at a transferrin iron saturation level usually considered to be normal. These relationships demonstrate the need for an increased iron supply in patients with erythroid marrow hyperplasia, if erythropoiesis is to proceed at maximal rates.

ANEMIA IN INFANTS WITH MILD INFECTIONS

A group of 467 healthy infants had Hgb, MCV, erythrocyte protoporphyrin (EP), serum ferritin (SF), serum iron (Fe) and TIBC measured as part of a nutritional evaluation in conjunction with the well child examination at 12 months of age. In addition to the nutritional history, the frequency of clinic visits within 3 months of examination related to infection (URI, otitis, gastroenteritis) was determined. Frequent recent infection visits were associated with a pattern of reduced Hgb, MCV, and Fe with elevated EP and SF that is also characteristic of the anemia of chronic inflammation. (In iron deficiency, SF is typically decreased.) Of the infants with ≥ 3 recent infections, 22% had Hgb<11.5 g/dl, in contrast to 9% of those with no infection (p=0.005,X2). A subgroup of 323 infants was treated with either placebo or iron (30 mg iron/day as ferrous sulfate) for 3 mo. The percentage of subjects with a≥1g/dl rise in Hgb was 35% in infants with ≥3 infection visits compared to 13% in those with no infection visits (p<0.001). Each of the response rates was slightly but not significantly higher in the iron treated compared to the placebo group. Mild, acute, antecedent infections contribute substantially to the frequency of low Hgb values in infants who are screened for iron deficiency.

Light-Induced Release of Protoporphyrin, But Not of Zinc Protoporphyrin, From Erythrocytes in a Patient With Greatly Elevated Erythrocyte Protoporphyrin

A patient with greatly increased erythrocyte protoporphyrin, but normal porphyrins in urine and feces, is described. The patient later developed a malignant lymphoma, and the reason why she accumulated protoporphyrin in her erythrocytes is not known. The protoporphyrin in the erythrocytes consisted of two types of protoporphyrin, free protoporphyrin (30%) and zinc protoporphyrin (70%). Upon irradiation of erythrocytes in the absence of albumin, protoporphyrin and zinc protoporphyrin, which were both bound to hemoglobin, were released. In contrast, when the irradiation was carried out in the presence of albumin, the photohemolysis was negligible, and there was release of free protoporphyrin, but not of zinc protoporphyrin, from the erythrocytes. In vivo albumin is present in the plasma and the results may help to explain why patients with erythropoietic protoporphyria (erythrocytes containing free protoporphyrin) are photosensitive, whereas patients with lead intoxication and iron deficiency (erythrocytes containing zinc protoporphyrin) are not.

Light-induced release of protoporphyrin, but not of zinc protoporphyrin, from erythrocytes in a patient with greatly elevated erythrocyte protoporphyrin

A patient with greatly increased erythrocyte protoporphyrin, but normal porphyrins in urine and feces, is described. The patient later developed a malignant lymphoma, and the reason why she accumulated protoporphyrin in her erythrocytes is not known. The protoporphyrin in the erythrocytes consisted of two types of protoporphyrin, free protoporphyrin (30%) and zinc protoporphyrin (70%). Upon irradiation of erythrocytes in the absence of albumin, protoporphyrin and zinc protoporphyrin, which were both bound to hemoglobin, were released. In contrast, when the irradiation was carried out in the presence of albumin, the photohemolysis was negligible, and there was release of free protoporphyrin, but not of zinc protoporphyrin, from the erythrocytes. In vivo albumin is present in the plasma and the results may help to explain why patients with erythropoietic protoporphyria (erythrocytes containing free protoporphyrin) are photosensitive, whereas patients with lead intoxication and iron deficiency (erythrocytes containing zinc protoporphyrin) are not.