Gas chromatographic-mass spectrometric analysis of urinary glycyrrhetinic acid: an aid in diagnosing liquorice abuse.
OBJECTIVE
Liquorice abuse can lead to severe clinical complications, caused by its active compound 18beta-glycyrrhetinic acid (18betaGA). 18betaGA inhibits dehydrogenase activity of 11beta-hydroxysteroid dehydrogenase (11betaHSD). This enzyme catalyses the interconversion between cortisol and cortisone and normally protects the mineralocorticoid receptor from being activated by cortisol. Diagnosing liquorice abuse can be notoriously difficult. The aim of our study was to develop an accurate and clinically applicable 18betaGA urinary assay.


METHODS
We developed a urinary 18betaGA assay based on gas chromatography and mass spectrometry (GCMS) with sufficient sensitivity to detect 18betaGA at low concentrations. The assay was validated in four volunteers consuming different amounts of liquorice. We applied its use in two patients with hypokalaemic hypertension and suppressed plasma renin activity and serum aldosterone, who were suspected of liquorice abuse.


RESULTS
The detection limit for 18betaGA of the GC assay was 10 microg L-1, which was lowered to 3 microg L-1 by subsequent application of MS. In all volunteers, urinary 18betaGA was detected during liquorice intake. Urinary 18betaGA remained detectable until 5 days after stopping continued liquorice intake and until at least 51 h after ingestion of a single large amount. Urinary 18betaGA was demonstrated in both patients, establishing a diagnosis of liquorice abuse. One patient showed changes in urinary cortisol metabolites, consistent with 11betaHSD inhibition. Changes in cortisol metabolites were less pronounced in the other patient.


CONCLUSIONS
Liquorice abuse can result in hypokalaemic hypertension with prolonged suppression of plasma renin activity and aldosterone concentration. This is caused by 18betaGA-mediated inhibition of 11betaHSD, resulting in activation of the renal mineralocorticoid receptor by cortisol. Urinary 18betaGA measurement by GCMS is a useful aid in establishing liquorice abuse.
Kerstens
M N
MN
Department of Endocrinology, University Hospital Groningen, Groningen, The Netherlands. m.n.kerstens@int.azg.nl
Guillaume
C P
CP
Wolthers
B G
BG
Dullaart
R P
RP
D000328:Adult; D002849:Chromatography, Gas / Q000379:methods*; D005260:Female; D006034:Glycyrrhetinic Acid / Q000652:urine*; D019695:Glycyrrhizic Acid / Q000009:adverse effects*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods*; D012680:Sensitivity and Specificity; D015813:Substance Abuse Detection / Q000379:methods*
D019695:Glycyrrhizic Acid; D006034:Glycyrrhetinic Acid; D006854:Hydrocortisone