Eur J Cardiothorac Surg 1999;16:273-275
© 1999 Elsevier Science NL
Gastric intrinsic factor production and vitamin B12 absorption after oesophageal resection using stomach as substitute
Erik Hjelmsa,
Poul Thirupb,
Lone Schoua
a Department of Cardiothoracic Surgery, Aalborg Hospital, Aalborg, Denmark
b Department of Medical Gastroenterology, Aalborg Hospital, Aalborg, Denmark
Corresponding author. Heart Centre, University Hospital, S-901 85 Umea, Sweden. Tel.: +46-90-785-3610; fax: +46-90-785-3601
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Abstract
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Objective: To investigate whether the use of the stomach as a substitute after oesophageal resections causes disturbances in vitamin B12 absorption due to deficient intrinsic factor (IF) production. Material and methods: Eleven patients operated upon with oesophageal resection a.m. Ivor Lewis, for malignant (10) or benign (1) conditions of the oesophagus were examined with a postoperative dual isotope technique 11–41 months (mean 25 months) after operation. Results: In two patients the test showed abnormally low absorption of vitamin B12. One of these probably due to incomplete urine collection during the test period. However, no patient showed deficient intrinsic factor production with absorption ratios between vitamin B12±IF of 0.87–1.14 (reference interval: 0.70–1.20). Conclusion: Deficiency of intrinsic factor is neither an obligatory nor a common occurrence after oesophageal resection with gastric substitute. However, vitamin B12 absorption may be low due to other factors, and should be looked for in all patients surviving more than a couple of months postoperatively.
Key Words: Oesophageal resection • Vitamin B12 • Intrinsic factor • Oesophageal cancer
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1. Introduction
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Absorption of vitamin B12 is a multi-step process beginning in the stomach with release of the vitamin from its protein binding in the food by the peptic activity of the stomach secrete. Subsequently it is attached to the glycoprotein intrinsic factor (IF) produced by the parietal cells of the mucousa in the gastric corpus and fundus. The actual absorption of the vitamin B12–IF complex takes place in the distal ileum by special receptors on the mucousal cells. From these cells it is transported to the circulation by the transport protein transcobalamin II.
With the abrupt and profound change of the anatomy and physiology after Ivor Lewis resection of the oesophagus using the ventricle as a conduit, some dysfunction of the upper gastrointestinal system could be expected and is also known to occur [1–3].
Most oesophageal resections are done for cancer of the oesophagus and the prognosis of this disease is gloomy with only few long-term survivals [4]. Probably due to these facts only very few patients have been investigated for vitamin B12 malabsorption post-operatively after Ivor Lewis resection. The purpose of the present study is to investigate to what extent the Ivor Lewis technique causes defect intrinsic factor production and to elucidate whether vitamin B12 malabsorption is a common occurrence post-operatively.
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2. Materials and methods
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Eleven patients operated on with oesophageal resection and a.m. Ivor Lewis during the period from November 1992 to June 1995 were examined for intrinsic factor (IF) production and vitamin B12 absorption with a dual isotope technique at a mean of 25 months post-operatively ranging from 11 to 41 months. Part of the ventricular fundus was preserved in all patients. Table 1 provides data concerning age, gender, type, and localisation of oesophageal lesion and interval from operation to examination. No patient demonstrated signs of megalocytic anaemia pre-operatively.
The study was in accordance with the Helsinki Declaration and was approved by the regional scientific ethical committee; the participants gave informed consent.
The dual isotope test of vitamin B12 absorption as described by Bell [5] was done with the Dicopac (Amersham International, Aylesbury, Buchs) test. The patients had two test capsules, one containing vitamin B12 tagged with Co58, (0.25 mµ), the other containing vitamin B12 Co57, (0.25 mµ) and IF. The capsules were followed by an intramuscular injection of untagged vitamin B12 (1 mg) as a flushing dose to secure B12 excretion in the urine. Urine was collected over 24 h by the patient at an ambulatory basis and delivered to the hospital laboratory for analysis of Co57 and Co58. Reference values are given in Table 2.
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Table 2. Results of the double isotope B12 absorption test in patients with oesophageal resection a.m. Ivor Lewis
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3. Results
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Two patients, patients number 6 and 9, had abnormally low absorption of vitamin B12. One of these, patient number 6, had probably incomplete urine collection, but the urine volume assembled was more than 2 l. He was 3 years after his operation and showed no signs of recurrence, but he was, as before the operation, a chronic alcoholic. The other patient, with low absorption, was 2 years after a palliative resection and was generally in poor condition with proven recurrence in the abdomen, severe weight loss, and a very low diuresis. However, both these patients had, as all other patients in this study, a normal ratio of Co + IF versus Co–IF demonstrating no important impairment of intrinsic factor production as seen in Table 2.
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4. Discussion
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Impaired absorption of vitamin B12 after oesophageal resection and the use of ventricle as substitute could be expected due to several factors. Not only impaired production of IF, but also vagal denervation of the gastro intestinal system and subsequent achlorhydria with possible change of bacterial flora in the small intestine may be important factors. Although resection of cardia was done in all cases and in some also resection of adjacent areas of greater and smaller curvature, no abnormal urine excretions of CO ± IF were found, indicating sufficient production of IF post-operatively. The decrease in perfusion pressure due to the elevated position of the gastric fundus post-operatively and the atrophic gastritis, which is found in up to 40% of patients [3] apparently, does not interfere with IF production.
In only two of 11 patients a decreased B12 absorption was demonstrated in terms of equally low urine excretion of both isotopes. One may be due to incomplete urine collection in a chronic alcoholic patient, but chronic pancreatitis may also play a role [6]. The other patient with abnormally low urinary excretion of both isotopes was emaciated and had swallow difficulties, which may have caused incomplete uptake of the isotope marked vitamin B12 preparations. Our findings of only two out of 11 cases of decreased absorption with no indication of insufficient IF production are in accordance with previous work on this subject. Inberg [1], found two of eight patients with abnormal Schilling test, but apparently they did not use a double isotope technique, so it is unclear whether low values were due to impaired IF production or other factors. Okada [2] found decreased vitamin B12 absorption in three out of nine patients. These three patients were studied for 1, 11, and 17 months after surgery, respectively. The patient studied 1 month post-operatively had a normal ratio between vitamin B12 with and without intrinsic factor, whereas the other two demonstrated IF deficiency. In the remaining six patients all with normal vitamin B12 absorption, the interval between examination and surgery was more than 22 months, which leads the authors to suggest that vitamin B12 absorption normalises after a period of approximately 2 years post-operatively. However, they have no longitudinal study of the individual patient to prove this.
Although our results and those of Inberg [1] and Okada [2] indicate that impaired intrinsic factor production is not a common occurrence after Ivor Lewis resection of the oesophagus, it does occur. As other factors also play a role in low vitamin B12 absorption, it seems appropriate to suggest that these patients should be controlled for vitamin B12 deficiency post-operatively. For long time survivors probably, with intervals, lifelong, as it has been demonstrated that patients who have compensated, not detectable lowered B12 absorption, e.g. after gastric resections, with age develop frank B12 deficiency and the haematologic, neurologic, and cardiovascular complications connected with this [7].
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References
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Received February 12, 1999;
received in revised form May 10, 1999;
accepted June 9, 1999.
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Abstract
1. Introduction
