Iron deficiency in pernicious anaemia: a neglected diagnosis

Iron deficiency in pernicious anemia: Specific features of iron deficient patients and preliminary data on response to iron supplementation

BACKGROUND & AIMS

While vitamin B12 (B12) deficiency is considered as the hallmark of pernicious anemia (PA), iron deficiency (ID) is also prevalent. Indeed, this auto immune gastritis is responsible for parietal cell atrophy and increase in gastric pH, leading to impaired iron absorption. We compared PA patients' features according to their iron status at PA diagnosis, and we assessed the iron status recovery after oral or intravenous iron supplementation.

METHODS

We prospectively included patients presenting with a newly diagnosed PA in a tertiary referral hospital between November 2018 and October 2020. Iron status was assessed at PA diagnosis then regularly during a standardized follow-up. In case of ID, the decision of treatment with oral and/or intravenous iron supplementation was left to the clinician convenience.

RESULTS

We included 28 patients with newly diagnosed PA. ID was observed in 21/28 (75.0%) patients: from the PA diagnosis in 13 patients, or during the follow-up in 8 patients. Iron deficient PA patients had higher plasma B12 (p = 0.04) and lower homocysteine levels (p = 0.04). Also, ID was independently associated with the 'APCA (anti-parietal cell antibodies) alone' immunological status (absence of anti-intrinsic factor antibodies) after adjustment for age, gender and B12 level (aOR 12.1 [1.1-141.8], p = 0.04). High level of APCA was associated with lower ferritin level. After 3 months of supplementation, 3/11 PA patients normalized the iron status with oral iron supplementation, versus 7/8 with intravenous iron supplementation (p = 0.02).

CONCLUSION

The high frequency of iron deficiency in PA highlights the interest of regular assessment of iron status in this condition. ID was associated with a profile including APCA alone and less pronounced B12 deficiency. Intravenous iron supplementation seemed to be more efficient than an oral supplementation in these preliminary data.

Is achlorhydria a cause of iron deficiency anemia?

We re-evaluated the old hypothesis that gastritis-induced achlorhydria is a cause of iron deficiency anemia (IDA) in humans. First, we analyzed the currently available research on the association between achlorhydria and IDA. When gastric acid secretion was measured after maximal stimulation, the frequency of achlorhydria (or severe hypochlorhydria) was 44% in patients with idiopathic IDA and 1.8% in healthy controls. In some patients with pernicious anemia, presumed achlorhydria preceded the development of IDA in time. However, we found no credible evidence that IDA caused gastritis or that IDA preceded the development of achlorhydria. Thus, correlational results favor achlorhydria as the causal factor in the association between achlorhydria and IDA. Second, we sought to determine whether gastritis and achlorhydria cause negative iron balance. When biosynthetic methods were used to isotopically label iron in food, achlorhydric patients were found to have severe malabsorption of nonheme iron, which persisted after the development of IDA. In 1 study, achlorhydria reduced the normal increase in heme-iron absorption from hemoglobin in response to iron deficiency. After an injection of isotopic iron into normal men, the physiologic loss of iron from the body was found to be 1 mg/d. Patients with chronic gastritis had excess fecal loss of isotopically tagged plasma iron. Calculations based on these results indicate that the absorption of iron from a typical Western diet by achlorhydric patients would be less than physiologic iron losses, creating a negative iron balance that could not be overcome by the adaptive increase in duodenal iron absorptive capacity that occurs in response to iron deficiency. The combination of results from these correlational and pathophysiologic studies supports the hypothesis that gastritis-induced achlorhydria can be an independent cause of IDA.

Cobalamin deficiency can mask depleted body iron reserves

Vitamin B12 deficiency impairs DNA synthesis and causes erythroblast apoptosis, resulting in anaemia from ineffective erythropoiesis. Iron and cobalamin deficiency are found together in patients for various reasons. We have observed that cobalamin deficiency masks iron deficiency in some patients. We hypothesised that iron is not used by erythroblasts because of ineffective erythropoiesis due to cobalamin deficiency. Therefore, we aimed to demonstrate that depleted iron body reserves are masked by cobalamin deficiency. Seventy-five patients who were diagnosed with cobalamin deficiency were enrolled in this study. Complete blood counts and serum levels of iron, unsaturated iron binding capacity (UIBC), ferritin, vitamin B12, and thyroid stimulant hormone were determined at diagnosis and after cobalamin therapy. Patients who had a combined deficiency at diagnosis and after cobalamin therapy were recorded. Before cobalamin therapy, we found increased serum iron levels (126.4 ± 63.4 µg/dL), decreased serum UIBC levels (143.7 ± 70.8 µg/dL), increased serum ferritin levels (192.5 ± 116.4 ng/mL), and increased transferrin saturation values (47.2 ± 23.5 %). After cobalamin therapy, serum iron levels (59.1 ± 30 µg/dL), serum ferritin levels (44.9 ± 38.9 ng/mL) and transferrin saturation values (17.5 ± 9.6 %) decreased, and serum UIBC levels (295.9 ± 80.6 µg/dL) increased. Significant differences were observed in all values (p < 0.0001). Seven patients (9.3 %) had iron deficiency before cobalamin therapy, 37 (49.3 %) had iron deficiency after cobalamin therapy, and a significant difference was detected between the proportions of patients who had iron deficiency (p < 0.0001). This study is important because insufficient data are available on this condition. Our results indicate that iron deficiency is common in patients with cobalamin deficiency, and that cobalamin deficiency can mask iron deficiency. Therefore, we suggest that all patients diagnosed with cobalamin deficiency should be screened for iron deficiency, particularly after cobalamin therapy.

The platelet count/mean corpuscular hemoglobin ratio distinguishes combined iron and vitamin B12 deficiency from uncomplicated iron deficiency

Combined deficiencies of iron and cobalamin are common. The aims of this study were to investigate the significance of the parameters of the complete blood count (CBC) in differentiating microcytic anemia due to pure iron deficiency anemia (IDA) from anemia due to combined deficiencies of vitamin B(12) and iron (IDA-B12). The study was carried out with 122 patients (100 female) who had microcytic red blood cell indices with IDA-B12 and 105 patients (95 female) with IDA. Group IDA-B12 patients had decreased hemoglobin levels, mean corpuscular volumes, mean corpuscular hemoglobin (MCH) levels, and MCH concentrations but had increased platelet counts (PLT). Using these parameters, we developed a PLT/MCH ratio parameter that has high values when IDA is accompanied by cobalamin deficiency. The cutoff value of >12.00, with a 74.6% sensitivity and a 41.9% specificity, appears to be the most convenient value for screening. We advise measuring the levels of cobalamin in patients with IDA associated with a high PLT/MCH ratio.

Prevalence and haemopoietic effects of low serum vitamin B12 levels in geriatric medical patients

The clinical significance of low serum vitamin B12 levels in elderly people is controversial. We aimed to document the prevalence of a low serum vitamin B12 (< 175 pmol/l) in patients referred to a geriatric medical unit, and to determine whether haemopoiesis is commonly affected in elderly patients with low serum vitamin B12. We studied prospectively 472 consecutive referrals to a geriatric medical unit; fifty-six (13%) had a low serum vitamin B12 level, of whom nineteen (34%) of the fifty-six also had evidence of Fe deficiency (serum ferritin < 45 ng/ml). Low vitamin B12 was associated with a raised mean erythrocyte volume (MCV; mean 96.0 (SD 6.7) fl), compared with a control group (91.7 (SD 6.0) fl; P = 0.001). However, only thirteen (23%) of the fifty-six patients with a low vitamin B12 had an MCV > or = 100 fl. Mean haemoglobin (Hb) levels were not significantly reduced in those with a low vitamin B12. In a subsequent study the haematological response to intramuscular hydroxocobalamin was examined in thirty-four patients with a low serum vitamin B12. Treatment resulted in a significant fall in MCV and rise in Hb; these effects could be detected both in those patients with an initially normal full blood count (change in MCV -1.2 (SD 1.2); Hb +0.5 (SD 0.6); P < 0.01) and in those with macrocytosis and/or anaemia (-9.1 (SD 11.8); +0.8 (SD 1.2); P < 0.05). A low serum vitamin B12 is common in geriatric medical patients. This is usually associated with an upset in erythropoiesis, although the abnormalities are often subtle and may not be apparent on inspection of the full blood count. Elderly patients with serum vitamin B12 < 175 pmol/l should be assumed to have vitamin deficiency even if their full blood count is normal.

Gastric as well as duodenal biopsies may be useful in the investigation of iron deficiency anaemia

BACKGROUND

Iron absorption is known to be impaired in the setting of gastric achlorhydria, yet gastric atrophy is not usually considered an aetiological factor for iron deficiency anaemia. We aimed to determine the prevalence of achlorhydric gastric atrophy in patients with iron deficiency and no identifiable source of gastrointestinal blood loss, and to assess whether gastric, as well as duodenal, biopsies should be routinely performed in these patients.

PATIENTS

Forty-one consecutive patients with iron deficiency anaemia and no specific gastrointestinal symptoms or evidence of a bleeding lesion on faecal occult blood testing or upper gastrointestinal or colonic endoscopy.

METHODS

As well as routine duodenal biopsies, samples were taken from gastric corpus and antrum for evidence of gastric atrophy. Achlorhydria was considered to be present if plasma gastrin measured on a sample obtained with the patient fasting was over 200 ng/l. Serum was tested for intrinsic factor and gastric parietal cell antibodies.

RESULTS

Haemoglobin concentrations ranged from 4.1 to 10.9 g/dl. Eight (20%) of the 41 patients had corpus-predominant or generalized atrophy and high plasma gastrin levels, of whom six had serum intrinsic factor and/or gastric parietal cell antibodies: two also had Giardia lamblia organisms in duodenal biopsies. Four other patients (10%) had villous atrophy of the duodenum.

CONCLUSIONS

As well as confirming the importance of seeking coeliac disease in patients with iron deficiency anaemia, our results suggest that achlorhydric gastric atrophy is also a common association. Gastric biopsies should be taken in patients with no other explanation for anaemia. The finding of Giardia organisms in two achlorhydric patients, with a possible contributory role, suggests that duodenal biopsies should be obtained even if serum coeliac-related antibodies are absent.

The Sydney System: auto-immune gastritis

The association of gastric auto-immunity with chronic gastritis has been recognized for more than 30 years. Despite this, little is known about the initiation of auto-immune gastric mucosal injury or the role of gastric auto-antibodies in this disease process. The current review describes recent progress in our understanding of these fundamental questions on the origin and progression of auto-immune gastritis. In addition, evidence is presented (epidemiologic, clinical, pathologic and experimental) that strongly supports the view that auto-immune gastritis is a distinctive category of chronic gastritis with significant long-term sequelae.

Vitamin B12 deficiency. Important new concepts in recognition

Vitamin B12 deficiency develops over a slowly progressive continuum. Early manifestations may be generalized weakness or fatigue, indigestion, diarrhea, or depression. Pernicious anemia is considered the classic cause, but others include malabsorption because of achlorhydria or other gastric dysfunction, fish tapeworm infection, and strict vegetarianism. Iron deficiency often coexists. Because presentation is often atypical, vitamin B12 deficiency is a diagnostic consideration whenever neuropsychiatric signs or symptoms are unexplained.

Coeliac disease and pernicious anaemia

Despite the often reported autoimmune basis for coeliac disease and pernicious anaemia, there have been only occasional reports of the two conditions occurring together. We wish to report of such an association occurring in a 61 year old patient and comment on the diagnostic and prognostic implications.