Urinary creatine and methylamine excretion following 4 × 5 g · day⁻¹ or 20 × 1 g · day⁻¹ of creatine monohydrate for 5 days

Abstract

In this study, we examined the effect of two creatine monohydrate supplementation regimes on 24-h urinary creatine and methylamine excretion. Nine male participants completed two trials, separated by 6 weeks. Participants ingested 4 × 5 g · day⁻¹ creatine monohydrate for 5 days in one trial and 20 × 1 g · day⁻¹ for 5 days in the other. We collected 24-h urine samples on 2 baseline days (days 1–2), during 5 days of supplementation (days 3–7), and for 2 days post-supplementation (days 8–9). Urine was assayed for creatine using high-performance liquid chromatography and methylamine using gas chromatography. Less creatine was excreted following the 20 × 1 g · day⁻¹ regime (49.25 ± 10.53 g) than the 4 × 5 g · day⁻¹ regime (62.32 ± 9.36 g) (mean ± s; P < 0.05). Mean total excretion of methylamine (n = 6) over days 3–7 was 8.61 ± 7.58 mg and 24.81 ± 25.76 mg on the 20 × 1 g · day⁻¹ and 4 × 5 g · day⁻¹ regimes, respectively (P < 0.05). The lower excretion of creatine using 20 × 1 g · day⁻¹ doses suggests a greater retention in the body and most probably in the muscle. Lower and more frequent doses of creatine monohydrate appear to further attenuate formation of methylamine.

Keywords:

• Creatine supplementation
• creatine excretion
• methylamine excretion
• supplementation regime