Persistent iron and folate deficiency in a patient with deletional hereditary persistence of fetal hemoglobin; the effect on the relative levels of Hb F and G gamma chains and the corresponding mRNAs

We describe a Black female who has suffered for many years from an (often) severe anemia (Hb 5-9 g/dl) with iron deficiency (serum Fe 8 microg/dl; TIBC 462 microg/dl; ferritin 7 ng/ml or less) and folate deficiency. The patient had hypermenorrhea which was appropriately treated resulting in an increase in hemoglobin level but not affecting the Fe deficiency. Splenomegaly was present, perhaps resulting from a clay-eating habit, although this was consistently denied. The patient had an alpha-thalassemia-2 (-3.7 kb) trait and a deletional hereditary persistence of fetal hemoglobin (HPFH) (type II) which were inherited from her father. Over the last six years the level of Hb F varied between 8.5 and 16% (25-29% in the father), while the G gamma value was also low (15-22% versus 32-34% in the father). Comparable reductions were seen in the relative levels of gamma-mRNA and G gamma-mRNA. These data support results published by Adams et al who showed a severe reduction in Hb F level in another HPFH heterozygote with Fe deficiency; these investigations suggested that a reduction in alpha-globin synthesis resulted in preferential formation of alpha beta dimers rather than alpha gamma dimers. Our data suggest that the decrease of Hb F and G gamma levels is due to a reduction in gamma-mRNA formation, mainly of the G gamma type, rather than through a posttranslational mechanism alone.

Prevalence of anemia, iron, folic acid and vitamin B12 deficiency in two Bari Indian communities from western Venezuela

The hematological status of 406 Bari indians from two communities was studied. One hundred and seventy nine individuals were from Campo Rosario a village located in a low arid plain south to the Perijá mountain range and 287 were from Saimadoyi, a fertile valley in the heart of the mountain. Anemia was found in 54% and 31% of the people from Campo Rosario and Saimadoyi respectively. Low serum iron was present in 28% of the population in both communities while low serum ferritin levels were encountered in 20% of the population from Campo Rosario and 5% of the people from Saimadoyi. A high prevalence of serum folate and vitamin B12 deficiency (91% and 64% respectively) was found in Campo Rosario, in contrast only 5% of the population from Saimadoyi had low folate and none were vitamin B12 deficient. While there was a positive significant correlation between hemoglobin and serum iron concentrations (r = 0.517, p < 0.001), no significative correlation was found between the other parameters studied. The high prevalence of anemia and nutrient deficiency among the Bari indians, can be attributed to inadequate diets and the varied diseases encountered in the population.

Reduced red-cell folate in mania

Forty-five hospitalised patients with DSM-III-R diagnosis of mania, were found to have a mean red-cell folate level of 193 nmol/l, as compared to 896 nmol/l in the control group (P < 0.00001). Assessment of serum folate in both groups showed no significant differences in the levels. Furthermore the manic patients and the controls were matched by the socio-economic status. This indicated that the reduced red-cell folate in mania is associated with the illness and not due to reduced absorption or dietary deficiency of folate. Considering previous studies that showed reduced red-cell folate in depression, our findings suggest that reduced red-cell folate occurred in both phases of bipolar disorders.

Acute methionine load-induced hyperhomocysteinemia enhances platelet aggregation, thromboxane biosynthesis, and macrophage-derived tissue factor activity in rats

A moderate elevation of plasma homocysteine is a risk factor for atherosclerosis and arterial and veinous thrombosis. However, the mechanisms leading to vascular disorders are poorly understood because studies that have investigated the potential atherothrombogenicity of hyperhomocysteinemia in vivo are scarce. Using a rat model, we were the first to show that dietary folic acid deficiency, a major cause of basal hyperhomocysteinemia, is associated with enhanced macrophage-derived tissue factor and platelet activities. We proposed that an homocysteine-induced oxidative stress may account for this hypercoagulable state. To determine the true thrombogenicity of moderate hyperhomocysteinemia and better understand its etiology, we have carried out an acute methionine load in control and folate-deficient animals. When rats were fed the control diet, a transient fourfold increase in plasma homocysteine levels was observed 2 h after the methionine administration. As with prolonged dietary folic acid deficiency, this methionine load potentiated the platelet aggregation in response to thrombin and ADP as well as the thrombin-induced thromboxane synthesis. It also stimulated the basal and lipopolysaccharide-induced tissue factor activity of peritoneal macrophages. These prothrombotic effects were associated with an increased lipid peroxidation characterized by an elevation of plasma conjugated dienes, lipid hydroperoxides, and thiobarbituric acid-reactive substances. When rats were fed a folic acid-deficient diet, the methionine load did not cause any further increase in plasma homocysteine concentration, platelet activation, macrophage tissue factor-dependent coagulation, or lipoperoxidation. Altogether, our data showed that the prethrombotic state due to both the altered remethylation and transsulfuration pathways resulted from the moderate elevation of circulating homocysteine. We conclude that moderate hyperhomocysteinemia plays a role in the development of a thrombogenic state that might be mediated by the occurrence of oxidative stress.

Folate economy in pregnancy

Pregnant women are prone to becoming folate deficient because there is a significant increase in folate requirement during pregnancy and folate intakes of pregnant women are often insufficient. Reduced folate levels in blood and neutrophilic hypersegmentation reflect a negative folate balance. Possible consequences of a low maternal folate status may be pregnancy complications such as abortion, abortus imminens, abruptio placentae, and congenital malformations. The role of folic acid in the etiology of neural tube defects has been discussed for decades. The importance of an adequate maternal folate status in the prevention of neural tube defects has been demonstrated by observational and controlled intervention trials. However, the mechanism of the protective effect of periconceptional folate supplementation is not completely understood. Metabolic disorders are probably involved in the pathogenesis of neural tube defects so that a relative folate shortage rather than folate deficiency seems to be responsible for the disturbed neural tube development, which can be compensated for by a higher folate intake.

Folic acid deficiency enhances oral contraceptive-induced platelet hyperactivity

In previous studies conducted in female rats and in women, oral contraceptives (OC) were found to induce a platelet hyperactivity that was related to an oxidative stress. Because cases of megaloblastic anemia have been reported to occur in women taking OC, these treatments are suspected of depleting folate stores. In the study presented herein, which was conducted in rats, we sought to determine the influence of dietary folic acid deficiency (FD) on the thrombogenicity of OC. Animals were fed for 6 weeks with either a folic acid-deficient diet (250 micrograms/kg folic acid) or a control diet (750 micrograms/kg). One-half of the animals in each group were treated with OC (ethinyl estradiol plus lynestrenol). FD and OC individually potentiated platelet aggregation in response to thrombin and ADP and the release and metabolism of arachidonic acid, in particular, the biosynthesis of thromboxane. These platelet activities were further enhanced in animals given both the folic acid-deficient diet and the OC treatment. In addition, FD enhanced the pro-oxidant state in OC-treated rats characterized by (1) a fall in platelet and plasma n-3 fatty acids, (2) an increase in plasma lipid peroxidation products such as conjugated dienes, lipid peroxides, and thiobarbituric reactive substances, (3) a rise in ex vivo erythrocyte susceptibility to free radicals. Moreover, we found that OC treatment led to a reduction of plasma and erythrocyte folate concentrations associated with a moderate hyperhomocysteinemia. Under our experimental conditions, we did not find significant synergistic effects between OC and FD. We propose that, although the untoward effects associated with the OC treatment may not primarily be dependent on FD, the folic acid deficiency magnified OC-induced oxidative stress, which resulted in platelet hyperactivity by elevating the pro-oxidant homocysteine plasma concentration. Despite the limitations of this animal model, the data of the present study suggest that in addition to cigarette smoking, inadequate folic acid intake might predispose those taking OC to vascular thrombosis.

Plasma total homocysteine concentrations in epileptic patients taking anticonvulsants

Plasma total homocysteine (tHcy) and serum folate (FA) concentrations were measured in 130 epileptic patients taking anticonvulsant drugs. A significant inverse correlation was found between FA and tHcy. This was greater in the older group (> or = 15 years) than in the younger group (1 to 14 years). There were four FA-deficient patients (FA concentration < 3 ng/mL regardless of symptoms), including three patients in the older group and one in the younger group. All FA-deficient patients had received long-term treatment (> 7 years) with multiple anticonvulsants. Their tHcy levels were higher than the 90th percentile of those in control subjects. Two patients showed extremely high levels of tHcy (57.9 and 29.1 mumol/L) and subnormal plasma methionine levels. After FA therapy, their tHcy decreased to levels the same as or less than those of control subjects and FA increased to above the normal range. Based on these findings, we conclude that measuring FA and tHcy concentrations may be useful for preventing thrombosis due to hyperhomocysteinemia in epileptic patients taking anticonvulsants, particularly those who receive long-term treatment with multiple agents.

Acute folate deficiency in a critically ill patient

A 19-year-old male patient developed thrombocytopenia and leukopenia due to acute folate deficiency while recovering from a multiple organ failure syndrome. Risk factors for acute folate deficiency are extensive tissue damage due to sepsis, trauma or surgery and acute renal failure requiring renal replacement therapy. The diagnosis is based on bone marrow examination showing marked megaloblastic changes whereas serum folate levels and red cell folate levels are normal. Recognition of this serious complication of critical illness is important because it should be readily prevented by folic acid therapy.

[Megaloblastic anemia: rapid and economical study]

The diagnosis of megaloblastic anaemias caused by cobalamine or folate deficiency are still difficult. The dosage of these two substances help to differenciate between both carencies, but it is not determinant of any of them and is an expensive method. Homocisteinuria (HC), methylmalonuria (MMA) and formiminoglutamic acid (FIGLU) are cheap tests which could help in the differential diagnosis, if they are used properly. We report 62 patients to whom we made these test simultaneously. All of the patients received 10 micrograms of vit B12 and after 72 hours, 1 mg/day of folic acid (for 3 days). In both cases waiting for the increase of reticulocytyes up to 150 x 10(9)/L as a form of therapeutic test of diagnosis. By this simple way we have detected 97.9% of specificity for cobalamin deficiency of the MMA test, and only 4.2% for HC. This last test had increased its specificity up to 91.6% in association with the negative FIGLU test. We have also found a high specificity (92.3%) for FIGLU due to the detection of folate deficiency, in opposition with other authors who had described it as low as 50%. We have also compared the costs of the 3 tests with the dosage of cobalamine and folate, and we have found that the formers are 11 times less expensive than the last ones.

Is metabolic evidence for vitamin B-12 and folate deficiency more frequent in elderly patients with Alzheimer's disease?

BACKGROUND

It is still unclear whether there is an association between Alzheimer's disease and vitamin B-12 or folate deficiency. This study was designed to investigate whether patients with Alzheimer's disease are particularly prone to metabolically significant cobalamin or folate deficiency as compared to nondemented hospitalized controls and healthy elderly controls living at home.

METHODS

Evaluation for the diagnosis of Alzheimer's disease, routine laboratory tests, serum folate and vitamin B-12, serum methylmalonic acid (MMA), total homocysteine (tHcy), and radiological tests was performed in 52 patients with Alzheimer's disease (AD), 50 nondemented hospitalized controls, and 49 healthy elderly subjects living at home.

RESULTS

Serum vitamin B-12 and folate levels are comparable between patients with AD, hospitalized control patients, and subjects living at home. Patients with AD have the highest serum MMA and tHcy levels. The MMA levels of patients with AD and hospitalized controls are not different, but the mean tHcy level is significantly higher in patients with AD as compared to nondemented patients or subjects living at home.

CONCLUSION

The interpretation of the vitamin B-12 and folate status in patients with AD depends largely on the methodology (i.e., serum vitamin vs metabolite levels) and the selection of the control group. Although patients with AD have the highest tHcy and MMA levels, metabolically significant vitamin B-12 and folate deficiency is also a substantial problem in nondemented elderly patients.

Folate, vitamin B12, and homocysteine in major depressive disorder

OBJECTIVE

The authors examined the relationships between levels of three metabolites (folate, vitamin B12, and homocysteine) and both depressive subtype and response to fluoxetine treatment in depressed patients.

METHOD

Fluoxetine, 20 mg/day for 8 weeks, was given to 213 outpatients with major depressive disorder. At baseline, depressive subtypes were assessed, and a blood sample was collected from each patient. Serum metabolite levels were assayed. Response to treatment was determined by percentage change in score on the 17-item Hamilton Depression Rating Scale.

RESULTS

Subjects with low folate levels were more likely to have melancholic depression and were significantly less likely to respond to fluoxetine. Homocysteine and B12 levels were not associated with depressive subtype or treatment response.

CONCLUSIONS

Overall, the results are consistent with findings linking low folate levels to poorer response to antidepressant treatment. Folate levels might be considered in the evaluation of depressed patients who do not respond to antidepressant treatment.

Marginal folate deficiency as a possible cause of hyperhomocystinaemia in stroke patients

It has been reported that patients with vascular disease seem to increase their concentration of plasma homocysteine after the acute episode, whereas reexamined control subjects do not change their concentration of plasma homocysteine over time. Since the main determinants of plasma homocysteine are serum cobalamin, blood folate and serum creatinine we measured these quantities in 20 control subjects and 49 stroke patients in the acute phase and at reexamination 1.5-2 years after acute stroke onset. There were no significant differences between the levels of blood folate, serum cobalamin and serum creatinine in the acute and convalescent phase of all 49 stroke patients. However, we noted a significant decrease of blood folate concentrations in a subgroup of patients (n = 25) who had increased plasma homocysteine concentrations. Thus the increase in plasma homocysteine concentrations in this group of patients may partly be caused by a marginal folate deficiency.

Folate and vitamin B12 status in a group of preschool children

An adequate intake of folates and vitamin B12 is essential for the rapid growth rates characteristic of infancy. However, little information exists on the prevalence of deficiencies of these nutrients in preschool children. The status of these vitamins was therefore evaluated in a group of 79 children between 2 and 6 years of age. A 5 day dietary record (including a Sunday) was kept for all subjects. All food taken at day care centres was monitored using "Precise individual weighing" and recorded by trained personnel. Measurements were made of serum and erythrocyte folate levels, vitamin B12 levels, number of red blood cells, haemoglobin and haematocrit levels, and mean corpuscular volume. Though the mean intake of folic acid surpassed recommended levels for this age group 31.4% of the subjects showed intakes below those recommended. 7.7% of the subjects showed serum folate levels between 3 and 6 ng/mL, values which indicate a moderate deficiency of this vitamin. A correlation was found between folate intake and serum folate levels r = 0.3654 (P < 0.01). Vitamin B12 intake was 438% that recommended. Only 2.9% of the subjects showed vitamin B12 intake below recommended and none showed serum values below 150 pg/ml, the lower normal limit below which deficiency is considered to exist.

CONCLUSION

Amongst preschool children, folate deficiency is probably much more common than vitamin B12 deficiency. However, its incidence is low, and much lower than that observed in other age groups.

Hyperhomocysteinemia induced by folic acid deficiency and methionine load--applications of a modified HPLC method

The increasing possibility that homocysteine might be involved in atherosclerosis in non-homocysteinuric subjects has required the measurement of low concentrations of this aminothiol in biological samples. The procedure described here represents an improvement of different HPLC methods. We utilized an isocratic HPLC system with fluorescence detection of plasma total homocysteine derivatized after reaction with ammonium 7-fluoro-benzo-2-oxa-1,3-diazole-4-sulphonate. With the help of the rapidly eluting internal standard N-acetyl-cysteine, the method ensures very good recovery (approximately 100%), reproducibility and precision (within-assay: 2.31%; day-to-day: 2.8%) in the physiological concentration range. This procedure allowed us to validate various animal models of hyperhomocysteinemia such as dietary folic acid deficiency in rat and acute methionine loads in rat and hamster. Using this method, we also confirmed that men have higher plasma total homocysteine levels than women. Due to its simplicity and reliability, our procedure is suitable for routine analysis of total homocysteine and other aminothiols (cysteine, cysteinyl-glycine and glutathione) in biological samples, as required in clinical and research laboratories.

Vitamin supplementation and other variables affecting serum homocysteine and methylmalonic acid concentrations in elderly men and women

OBJECTIVE

An elevated serum concentration of the metabolite, homocysteine (Hcys): 1) can indicate folate or vitamin B12 deficiency, 2) is an independent risk factor for vascular disease. The metabolite, methylmalonic acid (MMA), is elevated in deficiency of vitamin B12, but not folate. The purpose of this study was to determine the effect of self-selected vitamin supplementation and other variables on serum Hcys and MMA concentrations in elderly men and women.

METHODS

Serum concentrations of Hcys, MMA, folate and vitamin B12 were measured for elderly volunteers, age 68-96 years, and compared for those consuming (26 men, 25 women) and not consuming (24 men, 25 women) self-selected vitamin supplements.

RESULTS

Compared with the nonsupplemented group, the supplemented group had lower mean serum MMA (208 +/- 162 vs. 241 +/- 98 nmol/L [+/- SD]) and Hcys (9.5 +/- 2.6 vs. 11.2 +/- 2.7 mumol/L); and higher serum vitamin B12 (391 +/- 174 vs 292 +/- 107 pmol/L), and serum folate (46 +/- 15 vs. 24 +/- 10 nmol/L) p < 0.05. Among all 100 subjects, the prevalence of serum vitamin B12 < 221 pmol/L (300 pg/mL) was 18; MMA > 271 nmol/L, 16; Hcys > 16.2 mumol/L, 3; folate < 5.0 nmol/L, none. Based on serum vitamin B12 < 221 nmol/L with elevated serum MMA, vitamin B12 deficiency was probable in seven subjects, of whom two were supplemented. All three subjects with elevated serum Hcys had elevated serum MMA as well, suggesting vitamin B12 deficiency or renal insufficiency. A stepwise linear regression model for serum Hcys explained 61.7% of the variance, and included (in order) serum creatinine, folate, vitamin B12, albumin, age and body mass index (BMI). A model with serum MMA replacing serum vitamin B12 explained 64.1% of the variance in serum Hcys. Folate did not enter the model for supplemented subjects, supporting a "threshold effect": serum Hcys was inversely related to serum folate at lower serum folate (nonsupplemented subjects), but at higher serum folate (supplemented subjects), the relationship was flat. In supplemented subjects, serum Hcys was still related to vitamin B12 status, confirming that tissue deficiency of the vitamin was present.

CONCLUSIONS

Results showed potential usefulness of serum MMA and Hcys in identifying subclinical or tissue deficiency of vitamin B12. Clinicians should be aware of the risk of vitamin B12 deficiency in older people and of current screening algorithms using serum metabolites. These elderly volunteers had generally good folate status; nevertheless, some subjects seemed likely to benefit from an improvement in folate status that would reduce their serum Hcys within the normal range. The role of serum creatinine in the normal range in predicting serum Hcys, a vascular disease risk factor, remains unexplained.

[P-methylmalonate and P-homocysteine: metabolic markers of vitamin deficiencies. Background, validity and applications]

The clinical value of measuring concentrations of methylmalonate and total homocysteine in plasma as an aid in the diagnosis of cobalamin, folate and pyridoxine deficiencies has recently aroused interest. This review describes factors which affect the validity and interpretation of plasma (p-) methylmalonate and p-homocysteine. P-methylmalonate is not affected by preanalytical variables, there are no age- or sex-related differences and the intra-individual variation is negligible. The only important limitation to the specificity of an increased p-methylmalonate for cobalamin deficiency appears to be secondary accumulation due to impaired renal function. However, an elevated p-methylmalonate, which normalizes following cobalamin injections proves cobalamin deficiency, irrespective of renal function. P-homocysteine is affected by several preanalytical factors, so the utmost care is required in blood collection. Furthermore, p-homocysteine is dependent on age and sex. An elevated p-homocysteine is a less specific parameter for cobalamin deficiency, for which reason measurement in patients with suspected cobalamin deficiency is indicated only if p-methylmalonate is normal. Homocysteine is also increased in folate and pyridoxine deficiencies. Recently, moderate hyperhomocysteinaemia has become an established independent and significant risk factor for premature atherosclerotic cardiovascular diseases, suggesting a large future demand for p-homocysteine determinations.

Pro-thrombotic effects of a folic acid deficient diet in rat platelets and macrophages related to elevated homocysteine and decreased n-3 polyunsaturated fatty acids

Folic acid deficiency represents a vitamin deficiency that may be due either to an inadequacy of the dietary supply or to an increased requirement. It leads to a number of abnormalities including hematological, neurological and cardiovascular disorders. In this study, we investigated whether folic acid deficiency would influence platelet and macrophage activities. For 6 weeks, rats were fed a test diet containing a low amount of folic acid (250 mu g/kg) by comparison with a control diet (750 mu g/kg). We found 40 and 32 percent reductions (P < 0.05) of plasma and erythrocyte folates, respectively in the tested group. Peritoneal macrophages of the folic acid deficient animals exhibited greater (20 x) tissue factor (TF) activity than in the controls. We also found that folate depletion significantly enhanced the thrombin- and ADP-induced platelet aggregation (+64 and + 13 percent, respectively). Moreover, the results of incubations with radiolabeled arachidonic acid indicated that platelets of folic acid deficient animals incorporated more labeling than controls did. When stimulated with thrombin, the mobilization of arachidonate from platelet phospholipids and its subsequent formation of cyclooxygenase and lipoxygenase metabolites were enhanced in the deficient animals. In particular, thromboxane biosynthesis was markedly increased. The analysis of the plasma fatty acid composition showed a decrease in the plasma unsaturation index related to a marked fall of long chain (n-3) fatty acids which was also observed in platelets. These data suggested the occurrence of an oxidative stress in folic acid deficient animals which was confirmed by increases in plasma lipid peroxidation products (more than +20 percent) and an enhanced susceptibility of erythrocytes to free radicals (+23 percent). Altogether these data suggested that folic acid deficiency altered the circulating and cellular fatty acid composition and thus influenced the balance of the platelet eicosanoid synthesis. In addition, total homocysteine and glutathione concentrations were highly increased in plasma from folate-depleted rats. From these results, we conclude that folate deficiency can potentiate the coagulation pathway mediated by the macrophage TF as well as the platelet activation process. It is suggested that these dysfunctions might be related to the loss of (n-3) polyunsaturated fatty acids. The latter could result from an increased lipid peroxidation triggered by the folic acid deficiency-induced hyperhomocysteinemia.

The use of homocysteine and other metabolites in the specific diagnosis of vitamin B-12 deficiency

Vitamin B-12 (cobalamin) is a cofactor for only two enzymes, methionine synthase and L-methylmalonyl-CoA mutase. The serum vitamin B-12 concentration has been shown to have limitations in specificity and sensitivity in diagnosing vitamin B-12 deficiency and predicting response to therapy in subjects with clinical deficiency syndromes. Serum methylmalonic acid and/or total homocysteine concentrations have been shown to be elevated in almost every patient who has a clinical response to vitamin B-12. In elderly populations serum methylmalonic acid concentrations are elevated in the majority (60-66%) of subjects who have elevated total homocysteine concentrations, suggesting that vitamin B-12 deficiency (with or without associated folate deficiency) and/or chronic renal insufficiency may be the primary cause of most of the elevated total homocysteine concentrations in elderly populations. In such subjects vitamin B-12 and folate concentrations are both frequently in the low or low normal range, making differentiation of the clinical syndromes by use of serum vitamin concentrations problematic. Elevations of 2-methylcitric acid and cystathionine also result from vitamin B-12 deficiency. Serum N-methylglycine concentrations are normal in cobalamin deficiency but are increased in 40% of patients deficient in folate. In conclusion, elevations of methylmalonic acid and total homocysteine are very sensitive and specific in diagnosing vitamin B-12 deficiency and can be used to help differentiate vitamin B-12 deficiency from folate deficiency. Elevated total homocysteine concentrations that may have been attributed to folate deficiency in elderly subjects may in many instances be the result of vitamin B-12 deficiency even though serum vitamin B-12 concentrations are within normal limits.

Kinetics of total plasma homocysteine in subjects with hyperhomocysteinemia due to folate or cobalamin deficiency

Hyperhomocysteinemia in cobalamin and folate deficiency reflects an imbalance between influx and elimination of homocysteine (Hcy) in plasma. We investigated the kinetics of total Hcy (tHcy) in plasma after peroral Hcy administration in 19 volunteers with hyperhomocysteinemia (mean +/- SD: 67.1 +/- 39.5 mumol/L; range: 23.5-142.8 mumol/L) before and after supplementation with cobalamin and/or folate. Vitamin therapy decreased plasma tHcy to 21.8 +/- 14.1 mumol/L (range: 9.6-57.9 mumol/L) but caused only a marginal decline in the area under the curve (AUC) by 8% and plasma half-life by 21%. Using the equations for steady-state kinetics, these data indicate that mean plasma tHcy clearance is normal and that massive export of Hcy from tissues into plasma is the major cause of hyperhomocysteinemia in cobalamin or folate deficiency. However, the spread in AUC and plasma half-life values was large in hyperhomocysteinemia subjects, suggesting marked individual variability in tHcy clearance. Plasma methionine after Hcy loading did not increase before (0.9 +/- 6.8 mumol/L) but increased normally (12.8 +/- 4.6 mumol/L) after vitamin therapy, and the methionine response discriminated between vitamin-deficient and vitamin-replete subjects. In cobalamin- or folate-deficient subjects, only 6.5 +/- 3.0% of the Hcy dose was excreted unchanged in the urine, demonstrating that urinary Hcy excretion does not explain normal tHcy plasma clearance in subjects with impaired Hcy remethylation. Our data suggest that hyperhomocysteinemia in folate and cobalamin deficiency is related to increased influx of Hcy to plasma, and that the methionine synthase function is not an important determinant of elimination of Hcy from plasma. The large interindividual difference in Hcy clearance may be explained by variable adaptation to impaired methionine synthase function through increased Hcy flux through alternate metabolic pathways.

Biochemical folate, B12, and iron status of a group of pregnant adolescents accessed through the public health system in southern Ontario

PURPOSE

This study was designed to estimate the prevalence of biochemical iron, folate, and vitamin B12 depletion among a group of Canadian pregnant adolescents accessed through the Public Health system. Further, the impact of prenatal supplement use, chronologic age, gynecologic age, living arrangement, main source of income, postpartum custody plan, time of entry into prenatal care, and cigarette smoking on laboratory indices of the three nutrients were determined.

METHODS

Fifty-eight adolescents (14.5-19.0 years) were interviewed and blood samples were collected at 36 +/- 2 wk gestation.

RESULTS

Thirteen (22%) of the pregnant adolescents had anemia (hemoglobin < 110 g/L) and forty-five (78%) had depleted iron stores (plasma ferritin < 26.6 pmol/L or 12.0 micrograms/L). Twenty-five subjects had plasma B12 values in the sub-optimal range (< 148 pmol/L). Five of the 16 adolescents who infrequently or never consumed a folate-containing supplement had suboptimal erythrocyte folate values. Twenty-four percent of the subjects had hypersegmented neutrophils and of these, all and 71% of subjects had plasma ferritin and B12 concentrations in the suboptimal range, respectively. Self-reported folic acid and B12 supplement intakes were correlated with the corresponding blood values for these nutrients. In contrast, supplement iron use was only weakly, or not at all associated with biochemical indices of iron status.

CONCLUSIONS

Data from the present study indicate that plasma B12 and ferritin levels are low in a group of pregnant adolescents. These low values appear to be associated with a high prevalence of hypersegmented neutrophils. Prenatal supplement use appears to reduce the risk of low folate and B12 blood values but not biochemical iron status.