Trimethylaminuria: the detection of carriers using a trimethylamine load test.
A method potentially of value for investigating putative heterozygotes or carriers of trimethylaminuria by using a single oral dose of trimethylamine (TMA) is described. For healthy volunteers under normal dietary condition and following oral challenge with 300 mg and 600 mg TMA-base, over 90% of the urinary TMA was excreted in the form of TMA (93.6 +/- 1.6%). However, at a dose level of 900 mg TMA-base, there was clear evidence of saturation of the N-oxidation reaction as urinary TMA excretion declined to 77.2% (range 74.8-78.9) of the total dose of TMA. By contrast, in pedigree studies based upon propositi with trimethylaminuria, several parents were identified who showed clear evidence of saturation of the N-oxidation of TMA at the 600 mg TMA-base dose level, but not at 300 mg TMA-base or under normal dietary condition. In these individuals, the proportion of urinary TMA as trimethylamine N-oxide (TMAO) declined to (77.3 +/- 1.7%). Accordingly we propose that the oral administration of 600 mg TMA-base and the analysis of the following 0-8-h urine collection may be useful for the investigation of possible carriers of trimethylaminuria.
al-Waiz
M
M
Department of Pharmacology, St. Mary's Hospital, Medical School, London.
Ayesh
R
R
Mitchell
S C
SC
Idle
J R
JR
Smith
R L
RL
D000284:Administration, Oral; D000328:Adult; D006580:Genetic Carrier Screening; D006801:Humans; D008297:Male; D008661:Metabolism, Inborn Errors / Q000175:diagnosis / Q000235:genetics* / Q000652:urine; D008744:Methylamines / Q000008:administration & dosage / Q000652:urine*; D008875:Middle Aged
D008744:Methylamines; C005855:trimethyloxamine; C023336:trimethylamine