Strating, J.H. (2013) Wat is de waarde van de huidige vitamine B12 bepaling bij de voorspelling van een vitamine B12 deficiëntie. thesis, Medicine.
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Abstract
Background: Vitamin B12 deficiency is a common problem. However its clinical signs and symptoms have limited diagnostic value. The final diagnosis is commonly made on the results of laboratory tests that detect serum vitamin B12 concentrations. At the Deventer hospital vitamin B12 deficiency is defined as a vitamin B12 concentration <150 pmol/L. Previous studies have shown that concentrations between 100-200 pmol/L are not conclusive. This, in turn, may lead to patient overtreatment in the false-positive cases. Therefore additional tests are recommended if such concentrations are found. Methylmalonic acid (MMA) concentration is believed to be a more reliable indicator for a vitamin B12 deficiency. Objective: The study aims to determine the sensitivity and specificity of the serum vitamin B12 analysis, used in the laboratory at our institution. The main question is: what is the diagnostic value of the serum vitamin B12 concentration for identifying real vitamin B12 deficiency. Design: A retrospective database study was conducted on all vitamin B12 test results from between January 2005 until November 2012. These results were then compared to those of a 170 MMA tests. ROC-curves were used to identify the sensitivity and specificity of the different tests. Furthermore, hundred and twenty general practitioners and specialists were invited to participate in a digital questionnaire to find out which indications they used to order a vitamin B12 test. Results: When a MMA concentration >340 nmol/L was used as the gold standard to diagnose a vitamin B12 deficiency, a true deficiency was found in 45,8% of the patients with a vitamin B12 concentration of 100-150 pmol/L. This was 45,9% for the patients with a vitamin B12 151-200 pmol/L. Subsequently, a sensitivity and specificity of respectively 0,63 and 0,51 was found for the current vitamin B12 test. These findings were confirmed in the ROC-curve (area under the curve of vitamin B12 0,35 (95% CI 0,24-0,46). The survey results showed that the majority of the physicians (64,4%) are not familiar with methylmalonic acid. Conclusions: The present study suggests that the serum vitamin B12 concentration is a poor predictor of a true deficiency in comparison with MMA. Still, most physicians use serum vitamin B12 concentrations to diagnose vitamin B12 deficiency and seldom determine MMA levels. We therefore recommend standardization of additional methylmalonic acid analyses in the vitamin B12 100-300 pmol/L category to reduce the amount falsely identified vitamine B12 deficiencies and the subsequent overtreatment. The final benefits of such measures in terms of health and healthcare costs should, in the author’s eyes, be the subject of further studies.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Zeeman, M. Internist ouderengeneeskunde and Deventer Ziekenhuis and Geriatrie |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:48 |
| Last Modified: | 25 Jun 2020 10:48 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/941 |
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