Evaluation of the One-Hour (13)C-Propionate Breath Test in 49 Patients from a Single Center in Japan to Detect Vitamin B(12) Deficiency

BACKGROUND: Given the unavailability of reliable biomarkers for vitamin B(12) (VB(12)) deficiency in clinical settings, the usefulness of the (13)C-propionate breath test (PBT), utilizing VB(12) as a coenzyme of methylmalonyl-CoA in propionate metabolism, as a diagnostic modality for VB(12) 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 VB(12) deficiency in 49 patients with suspected VB(12) deficiency. MATERIAL/METHODS: We collected 100–200 mL breath gas every 10 min until 1 h after the administration of 1 g of (13)C-propionate from 49 patients (31 men, 18 women; median age, 70 years) with clinically suspected VB(12) deficiency and calculated the (13)CO(2) recovered in the breath per hour as the recovery rate (RR [%dose/h]) from (13)CO(2)/(12)CO(2) using infrared isotope spectrometry. We compared the RRs between groups: (1) with serum VB(12) levels ≥145 pg/mL and <145 pg/mL, (2) with mean corpuscular volume ≤100 fL and >100 fL, and 3) pre- and post-VB(12) supplementation. RESULTS: The RRs peaked within 30 min. The RRs at 20 min (RR(20)) and 30 min (RR(30)) were significantly lower in macrocytotic patients (41.28 vs 50.07, p=0.026 and 37.82 vs 43.93, P=0.003). The RR(30) was higher in the supplemented patients (41.93 vs 32.84, P=0.024). There was no significant difference in RRs between the patients with normal and low serum VB(12) levels. CONCLUSIONS: The 1-h PBT can be a diagnostic modality for VB(12) deficiency because 1 h is a sufficient collection time.