Erythrocyte folate levels: a clinical study

B vitamin blood concentrations and one-carbon metabolism polymorphisms in a sample of Italian women and men attending a unit of transfusion medicine: a cross-sectional study

PURPOSE

To define blood status of folate, vitamin B12, vitamin B6, homocysteine, and major one-carbon metabolism-related polymorphisms in healthy, males and females blood donors, aged 18-65 years were evaluated. General characteristics and lifestyle factors were also investigated.

METHODS

An explorative cross-sectional study design was used to evaluate a sample of blood donors attending the Unit of Transfusion Medicine of the Verona University Hospital, Italy. From April 2016 to May 2018, 499 subjects were enrolled (255 men, 244 women of whom 155 of childbearing age). Major clinical characteristics including lifestyle and dietary habits, B vitamins and homocysteine were analyzed. The MTHFR 677 C>T, cSHMT 1420 C>T, DHFR 19 bp ins/del, RFC1 80 G>A polymorphisms were also determined.

RESULTS

Mean plasma concentrations of folate, vitamin B12, vitamin B6 and homocysteine were 14.2 nmol/L (95% CI 13.7-14.8), 271.9 pmol/L (95% CI 262.6-281.5), 51.0 nmol/L (95% CI 48.7-53.4) and 13.5 µmol/L (95% CI 13.1-14.0), respectively. Plasma folate, was adequate (> 15 nmol/L) in 44.7% of all subjects, 39.0% of males and 42.5% of women < 45 years. Similarly, vitamin B12 was adequate (> 350 pmol/L) in 25.1% of all subjects and in 20.3% of men ≥ 45 years. The rare allele frequencies were 0.21 for MTHFR 677TT, 0.11 for cSHMT 1420TT, 0.18 for DHFR 19 bp del/del, 0.20 for RFC1 80AA, and a gene-nutrient interaction was confirmed for folate concentrations according to MTHFR 677C>T and DHFR 19 bp del/del.

CONCLUSION

An Italian sample of healthy blood donors shows that an adequate concentration of plasma folate and vitamin B12 is reached only in a limited percentage of subjects, thus encouraging consideration for specific public health strategies.

Evidence for potential underestimation of clinical folate deficiency in resource-limited countries using blood tests

Although a low serum folate concentration is a useful biomarker of pure folate deficiency, the presence of vitamin B12 deficiency or hemolysis or both in individuals with low folate status predictably raises serum folate levels. Therefore, in resource-limited settings where dietary folate deficiency can coexist with vitamin B12 deficiency or malaria or both, the serum folate concentration can range from normal to high, leading to serious underestimation of tissue folate status. This review traces the genesis of an inappropriate overreliance on the serum folate concentration to rule out folate deficiency in vulnerable populations of women and children. Of significance, without due consideration of a chronically inadequate dietary folate intake, authors of influential studies have likely wrongly judged these populations to have an adequate folate status. Through repetition, this error has led to a dangerous entry into the contemporary medical literature that folate deficiency is rare in women and children. As a consequence, many millions of under-resourced women and children with mild to moderate tissue folate deficiency may have been deprived of folate replacement. This review uses historical documents to challenge earlier conclusions and re-emphasizes the need for contextual integration of clinical information in resource-limited settings.

The association of folate and depression: A meta-analysis

BACKGROUND

Previous research suggested that folate levels play an important role in the etiology and course of depression. However, the literature has been inconsistent with regard to differences in folate level between individuals with and without depression. The present meta-analysis synthesized the results of previous studies to examine whether individuals with depression had lower levels of folate than individuals without depression.

METHODS

Meta-analytic procedures were conducted in accordance with PRISMA guidelines. Studies evaluating folate levels in individuals with and without depression via red blood cell folate, serum folate, or dietary intake of folate methods were identified via PsycINFO and PubMed. Random-effects meta-analysis was conducted using Hedge's g, and moderation analysis was used for both folate measurement method and population type. Study heterogeneity was assessed with I² and publication bias was qualitatively assessed via funnel plot and quantitatively assessed with the trim-and-fill method and Begg's adjusted rank test.

RESULTS

We found a significant, small effect size, such that individuals with depression had lower folate levels than those without depression, Hedge's g = -0.24 (95% CI = -0.31, -0.16), p < 0.001. Study heterogeneity was high (I² = 84.88%), and neither folate measurement method nor population accounted for study heterogeneity.

CONCLUSIONS

Individuals with depression have lower serum levels of folate and dietary folate intake than individuals without depression. Given that previous literature suggested folate supplementation improved the efficacy of traditional antidepressant medications, future research on folate supplementation in depression is warranted and clinicians may wish to consider folate supplementation for patients with depression.

The biomarker-based validity of a food frequency questionnaire to assess the intake status of folate, pyridoxine and cobalamin among Iranian primary breast cancer patients

BACKGROUND/OBJECTIVES

Folate, pyridoxine and cobalamin are coenzymatically essential in one-carbon methyl metabolism, and their deficiencies could explain some alterations during breast carcinogenesis. We aimed to evaluate the validity of folate, pyridoxine and cobalamin estimates from a food frequency questionnaire (FFQ) on the basis of their corresponding fasting plasma biomarkers, in breast cancer (BC) patients.

SUBJECTS/METHODS

In a prospective, consecutive case series, 149 women with primary BC aged between 30 and 69 years as a representative sample of Iranian women with BC were recruited. The 136-item FFQ was used for the validity assay. Fasting plasma folate and cobalamin were tested by automated electrochemiluminescence. The high-pressure liquid chromatography with fluorescence detection was used to determine the plasma levels of pyridoxal-5'-phosphate (PLP) and total homocysteine (tHcy).

RESULTS

Area under the curve (AUC) for assessing the diagnostic accuracy of folate-related data through an FFQ was 0.74 (P<0.01) in the reference model (folate plasma level<5.9 ng/ml), with sensitivity and specificity of 68% and 63%, respectively. The positive and negative predictive values (PPV and NPV) were 96.9% and 96.8%, respectively. The AUC for cobalamin intake in the reference model (plasma cobalamin<260 pmol/l) was 0.64 (P<0.01), with 60% sensitivity and 61% specificity. Although tHcy ≥10.0 μmol/l was used as reference indicator, the folate intake (AUC=0.71, P<0.01) and cobalamin intake status (AUC=0.67, P<0.05) were also determined appropriately by FFQ.

CONCLUSIONS

Dietary folate and cobalamin estimates from FFQ were significantly correlated with their fasting plasma concentrations. Our data supported the validity of new FFQ to rank individuals by dietary intake status of folate and cobalamin.

Folate, vitamin B12 and homocysteine status in an Italian blood donor population

BACKGROUND AND AIMS

The relevance of folate, other B-vitamins and homocysteine (Hcy) for the occurrence or prevention of several diseases has induced growing interest. Unfortunately, little evidence is available regarding B-vitamin concentrations in Italy. This study evaluated in a region of middle-southern Italy, folate, vitamin B12 and Hcy concentrations and the prevalence of their ideal blood levels. The main determinants of B-vitamins and Hcy were also considered.

METHODS AND RESULTS

Male and female blood donors (n=240), aged 18-66 years and living in Molise region (Italy), were enrolled in the study. They completed a brief questionnaire concerning fruit and vegetables intake, physical activity and smoking; serum and red blood cell (RBC) folate and serum vitamin B12 were measured by an immunoassay on an automated analyzer. Total Hcy was measured by high performance liquid chromatography (HPLC). Geometric means of serum folate, RBC folate and serum vitamin B12 were 10.8nmoll(-1), 426.0nmoll(-1) and 245.0pmoll(-1), respectively. Only 22.5%, 24.2% and 16.3% of blood donors showed an adequate level of serum folate, RBC folate or serum vitamin B12 respectively. When a cut-off of RBC folate ≥906nmoll(-1) was used no women of childbearing age had adequate levels. A geometric mean of 14.0μmoll(-1) was found for total Hcy, with an ideal concentration in 12.1% of subjects. Folate concentration was higher in women and non-smokers and in subjects with higher consumption of fruit and vegetable.

CONCLUSION

This study shows a low-moderate B-vitamins status in middle-southern Italy, associated with an inadequate fruit and vegetable consumption. A public health strategy should be undertaken to encourage a B-vitamin-rich diet with the addition of vitamin supplements or vitamin fortified foods in population subgroups with special needs.

Serum folate is a reliable indicator of hyperhomocysteinemia and borderline hyperhomocysteinemia in young adults

Serum folate has been shown to correlate well with fasting plasma homocysteine; however, erythrocyte folate concentration is a better index of tissue folate stores and probably could be a more reliable indicator for reflecting long-term supply of the vitamin and homocysteine status. The present study was undertaken to test the hypothesis that serum folate and erythrocyte folate levels had a different degree of correlation to fasting plasma homocysteine in young Taiwanese adults. This study had a cross-sectional design. Healthy young adults were divided into either a hyperhomocysteinemia (HHcy; > or =14.9 micromol/L; n = 13), borderline HHcy (BHcy; fasting homocysteine, 14.9-10.2 micromol/L; n = 52), or normohomocysteinemia (fasting homocysteine, <10.2 micromol/L; n = 65) groups based on fasting homocysteine levels. The concentrations of plasma fasting homocysteine, serum folate, erythrocyte folate, vitamin B(12), and plasma pyridoxal 5'-phosphate were measured. Fasting homocysteine was only significantly and inversely affected by serum folate (beta = -0.21, P < .05) concentration after adjusting for potential confounders. Only serum folate concentration remained to decrease the risk of fasting HHcy (odds ratio, 0.73; confidence interval, 0.56-0.95) after the other B vitamins were additionally adjusted. Serum folate also had the highest area under the receiver operating characteristic (AUC) curve to predict the risk of HHcy (AUC, 0.81) and BHcy (AUC, 0.77). Serum folate is a reliable indicator of fasting hyperhyperhomocysteinemia and BHcy in young adults.

Validation of a composite scoring scheme in the diagnosis of folate deficiency in a pediatric and adolescent dialysis cohort

BACKGROUND

Laboratory indices are often poorly diagnostic of folate deficiency (FD). Compared with iron depletion in hemodialysis (HD) populations, the impact of FD is less appreciated. The composite scoring of hematologic indices of FD may facilitate a prompt and accurate diagnosis, and enhance operational research on folic acid therapy.

OBJECTIVE

Our objectives were to (1) validate composite scores of folate diagnostic indices, and (2) determine the reliability index of the diagnostic tool.

METHODS

A cohort of 30 subjects, with a mean age of 16 (SD +/- 3.2 years), on HD and erythropoietin (EPO) for a minimum of 3 months was studied. After a baseline hematologic assessment, routine folates were administered for 6 months. Composite FD scores (FDS) of baseline mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), random distribution width (RDW), and hemoglobin were determined. Validation and reliability statistics were then analyzed, using the quantitative change in red blood cell folate/plasma homocysteine, or EPO requirement after 6 months of folate use, as diagnostic criteria.

RESULTS

The mean FDS for FD and non-FD subsets were 3.0 +/- 1.3 and 1.4 +/- 0.9, respectively (analysis of variance; P = .0001). The correlation coefficient, r(2), between FD total and FDS was 0.61 (P = .001), and the coefficient between 2 (weekly) values of RDW, MCV, MCH, and MCHC was >0.84 (P = .0001). Scoring tools derived from the first (P = .002) and second (P = .01) halves of the laboratory indices remained discriminatory for the FD and non-FD groups. Baseline serum folate is poorly specific for FD, whereas FD score >or=3 had sensitivity, specificity, and positive and negative predictive values close to 90%.

CONCLUSIONS

Composite scoring of erythrocyte indices was predictive of the FD diagnosis, as defined by the quantitative response of red blood cell folate, homocysteine, and EPO dose to folate therapeutic intervention. The diagnostic items yielded a high reliability coefficient. The FDS scheme is a potential tool for the diagnosis and surveillance of FD, particularly in at-risk populations (e.g., dialysis subjects).

Clinical utility of folic acid testing for patients with anemia or dementia

BACKGROUND

Serum folic acid tests are routinely ordered by physicians for evaluating anemia and sometimes ordered for evaluating dementia and altered mental status.

OBJECTIVE

To determine the utility of routine folic acid testing for patients with anemia or dementia/altered mental status in the era of folic acid fortification.

DESIGN

Retrospective analysis of consecutive folic acid tests performed on adults over a 4-month period; chart review of patients without anemia.

MEASUREMENTS AND MAIN RESULTS

Serum folic acid level, mean corpuscular volume (MCV), and hematocrit. We reviewed 1,007 folic acid tests performed on 980 patients. The average age was 63.8 years, and 62% of the tests were from outpatient facilities. Only 4 (0.4%) patients had folic acid levels <3 ng/mL, while 10 (1%) patients had levels of 3-4 ng/mL (borderline). Thirty-five percent of the folic acid tests were performed on patients who were not anemic; most of these were ordered to evaluate dementia or altered mental status and folic acid level was normal in all these patients. Only 7% of the patients tested had a macrocytic anemia; these patients were more likely than those without macrocytic anemia to have low folic acid levels (2.8% vs 0.4%, p < .03).

CONCLUSION

Low serum folic acid levels were rarely detected in a series of patients being evaluated for anemia, dementia, or altered mental status. The test should be reserved for patients with macrocytic anemia and those at high risk for folic acid deficiency.

Diagnosis of megaloblastic anaemias

There are a large number of causes of megaloblastic anaemia. The most frequent are disorders resulting in vitamin B(12) or folate deficiency. The diagnostic process often consists first of establishing the presence of B(12) or folate deficiency and then of determining the cause of deficiency. The blood count, blood film, serum B(12) assay, and red cell and serum folate assays are the primary investigations. Other useful investigations include serum/plasma methylmalonic acid (MMA), plasma total homocysteine (tHCYS) and serum holo-transcobalamin II assays. All currently used tests have limitations regarding specificity or sensitivity or both and the metabolite assays are not widely available. An understanding of these limitations is essential in formulating any diagnostic strategy. The wide use of serum B(12) and metabolite assays has resulted in the increasingly early diagnosis of B(12) deficiency, often in patients without B(12)-related symptoms (subclinical deficiency). Food cobalamin malabsorption is the most frequent cause of a low serum B(12). At least 25% of low serum B(12) levels are not associated with elevated metabolite levels and may not indicate B(12) deficiency. Some of these are caused by partial deficiency of transcobalamine I.

Is there a role for folate determinations in current clinical practice in the USA?

Our objectives were to determine the likelihood of true folate deficiency among patients tested for this disorder, to identify whether there were differences between the clinical indications for folate testing in folate-normal and folate-deficient patients and to assess the impact of a diagnosis of folate deficiency on patient management. The results of all blood samples analyzed for serum and erythrocyte folate levels during the year 2001 at the Cleveland Clinic Foundation were retrieved. Folate deficient patients were identified and their medical charts were reviewed to determine the indications, patient characteristics, and impact of this diagnosis on patient management. For comparison, medical chart review was also conducted on a control group composed of an equal number of randomly selected patients with normal serum folate values. A total of 6024 (4689 serum and 1335 erythrocyte) samples from 4985 patients were collected. In the study, 77 (1.6%) of the serum folate levels, from 74 patients, were identified as low. When compared with the control group, patients with low serum folate levels had lower hemoglobin and a greater red cell distribution width. Mean corpuscular volume, however, did not differ between the two groups. No significant differences in the clinical indications for serum folate level determinations could be identified. Only 39 of the 74 patients with low serum folate levels were given folate replacement, representing only 0.9% of the clinically suspected and tested patients. We conclude that determination of serum folate level infrequently led to appropriate folate replacement therapy. Moreover, even when suspected, true folic acid deficiency is rare and clinical indications are not helpful in diagnosis.

Plasma folate as marker of folate status in epidemiological studies: the European Investigation into Cancer and Nutrition (EPIC)-Potsdam study

Folate deficiency is often discussed as a potential risk factor for CVD and some cancers. Reliable assessment of folate status in large-scale epidemiological studies is therefore of major importance. The present study assessed the value of plasma folate (PF) compared with erythrocyte folate (EF) as a marker of folate status in 363 participants in the European Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort. EF and PF, total homocysteine (tHcy), pyridoxine, cobalamin, creatinine, total protein and packed cell volume were determined; glutamate carboxypeptidase (GCP) C1561T, reduced folate carrier (RFC) G80A and methylenetetrahydrofolate (MTHFR) C677T polymorphisms were analysed. Anthropometric measurements were taken and dietary intake was assessed with the EPIC-Potsdam food-frequency questionnaire. Comparison of EF and PF with factors that may modulate their concentrations was performed. Cross-classification of blood folates in quintile categories resulted in correct classification into the same or adjacent category of 75.5 % of all subjects. Age, BMI, pyridoxine and cobalamin, fruit and vegetable intake, and vitamin supplementation 24 h before blood draw were positively associated with EF and with PF. For tHcy an inverse association was found. Participants with the MTHFR 677TT genotype showed significantly elevated EF concentrations compared with those with 677CT genotype; EF and PF were more strongly correlated (r 0.78, P<0.0001) for participants with MTHFR 677TT genotype than for those with the 677CC or 677CT genotype. In summary, our present results indicate that plasma folate seems to be a suitable marker for assessment of folate status for use in large-scale epidemiological studies.

Red cell or serum folate? Results from the National Pathology Alliance benchmarking review

AIMS

The National Pathology Alliance benchmarking review has completed five years of data collection and analysis of the workload and organisation of haematology laboratories in the UK. This study analyses variation in practice in how laboratories respond to a request to determine whether or not a patient has folate deficiency.

METHODS

A three year analysis of workload data on the number of serum/plasma folate and red cell folate assays performed on an annual basis for the period 1 April 1999 to 31 March 2002.

RESULTS

Three diagnostic testing strategies were found, namely: serum/plasma folate only, red cell folate only, and both serum/plasma folate and red cell folate.

CONCLUSION

Evidence from the literature indicates that serum folate measurements provide equivalent information to red cell folate measurements when attempting to determine whether folate deficiency is present. There seems to be no basis for the routine testing of all samples for serum/plasma folate and a red cell folate.

Facts and Recommendations about Total Homocysteine Determinations: An Expert Opinion

Background: Measurement of plasma total homocysteine has become common as new methods have been introduced. A wide range of disorders are associated with increased concentrations of total homocysteine. The purpose of this review is to provide an international expert opinion on the practical aspects of total homocysteine determinations in clinical practice and in the research setting and on the relevance of total homocysteine measurements as diagnostic or screening tests in several target populations.

Methods: Published data available on Medline were used as the basis for the recommendations. Drafts of the recommendations were critically discussed at meetings over a period of 3 years.

Outcome: This review is divided into two sections: (a) determination of homocysteine (methods and their performance, sample collection and handling, biological determinants, reference intervals, within-person variability, and methionine loading test); and (b) risk assessment and disease diagnosis (homocystinuria, folate and cobalamin deficiencies, cardiovascular disease, renal failure, psychiatric disorders and cognitive impairment, pregnancy complications and birth defects, and screening of elderly and newborns). Each of these subsections concludes with a separate series of recommendations to assist the clinician and the research scientist in making informed decisions. The review concludes with a list of unresolved questions.

Relation between lung function and RBC distribution width in a population-based study

STUDY OBJECTIVES

Pulmonary function is dependent not only on smoking, but also on nutritional status. Since an increased RBC distribution width (RDW) has been associated with nutritional deficiencies, we postulated that RDW has an inverse relation to pulmonary function. The purpose of this study was to test this hypothesis.

DESIGN AND SETTING

A cross-sectional study was conducted of a random sample of the general population in western New York.

PARTICIPANTS

A total of 1,616 subjects of both genders who were aged 35 to 79 years and were free of respiratory disease.

INTERVENTIONS

None.

MEASUREMENTS

Pulmonary function was assessed from FEV(1), FVC, height, body weight, total pack-years of smoking, smoking status, hemoglobin concentration, and hematologic indexes, eosinophil count, education, and blood levels of retinol, beta-cryptoxanthin, and vitamin E.

RESULTS

We found a direct relation between RDW and the number of pack-years of smoking and smoking status, and an inverse relation between FEV(1) and FVC with RDW, even when potentially confounding variables such as smoking were taken into account. When the variability of FEV(1) due to smoking was used for comparison, an additional 27% of that variability in FEV(1) was explained by variations in antioxidant vitamin levels, and another 24% by RDW.

CONCLUSIONS

The results confirmed our hypothesis that there is an inverse relation between RDW and pulmonary function, and raise the possibility that RDW may be a biomarker for as-yet unidentified nutrients that affect pulmonary function.

Laboratory values, symptoms and survival in an 80-year-old population

Medical, psychological and sociological factors were related to laboratory values in an 80-year-old population encompassing 211 persons. 21% of the men and 17% of the women had elevated ESR. 36% had elevated blood glucose (7% had diabetes). 13% of the men and 7% of the women had anaemia. Persons with anaemia generally had a lower quality of life compared with non-anaemic persons. Low haemoglobin, elevated ESR and low serum iron were all associated with impaired subjective and objective health. There were no significant correlations between the laboratory data and psychological and social parameters. The survival over 5 years was significantly decreased for those with anaemia, elevated ESR, high white blood count, high blood glucose, low serum iron or deviating serum potassium.