Evaluation of the One-Hour 13C-Propionate Breath Test in 49 Patients from a Single Center in Japan to Detect Vitamin B12 Deficiency

Background: Given the unavailability of reliable biomarkers for vitamin B12 (VB12) deficiency in clinical settings, the useful-ness of the 13C-propionate breath test (PBT), utilizing VB12 as a coenzyme of methylmalonyl-CoA in propionate metabolism, as a diagnostic modality for VB12 deficiency has been studied. However, a collection time of 2 h reduces its convenience. Hence, we evaluated the effectiveness of 1-h PBT for detecting VB12 deficiency in 49 patients with suspected VB12 deficiency.Material/Methods: We collected 100-200 mL breath gas every 10 min until 1 h after the administration of 1 g of 13C-propionate from 49 patients (31 men, 18 women; median age, 70 years) with clinically suspected VB12 deficiency and calculat-ed the 13CO2 recovered in the breath per hour as the recovery rate (RR [%dose/h]) from 13CO2/12CO2 using infra -red isotope spectrometry. We compared the RRs between groups: (1) with serum VB12 levels 3145 pg/mL and <145 pg/mL, (2) with mean corpuscular volume 100 pound fL and >100 fL, and 3) pre-and post-VB12 supplementation.Results: The RRs peaked within 30 min. The RRs at 20 min (RR20) and 30 min (RR30) were significantly lower in macrocy-totic patients (41.28 vs 50.07, p=0.026 and 37.82 vs 43.93, P=0.003). The RR30 was higher in the supplement-ed patients (41.93 vs 32.84, P=0.024). There was no significant difference in RRs between the patients with normal and low serum VB12 levels.Conclusions: The 1-h PBT can be a diagnostic modality for VB12 deficiency because 1 h is a sufficient collection time.