Identification of glycyrrhizin metabolites in humans and of a potential biomarker of liquorice-induced pseudoaldosteronism: a multi-centre cross-sectional study.

Liquorice [main ingredient, glycyrrhizin (GL)] is widely used as a food sweetener and herbal medicine. Occasionally, liquorice consumption causes pseudoaldosteronism as a side effect which causes oedema, hypokalaemia, and hypertension due to hyperactivity of mineral corticoid receptor. We aimed to detect GL metabolites in human blood and urine samples and to determine the pathological relationship between GL metabolites and pseudoaldosteronism. For this multi-centre, retrospective, cross-sectional study, we recruited patients who had visited Center for Kampo Medicine in Keio University Hospital, Department of Japanese Oriental (Kampo) Medicine in Chiba University Hospital, Clinic of Japanese Oriental (Kampo) Medicine in Kanazawa University Hospital, and Department of Oriental Medicine in Kameda Medical Center from November 2011 to July 2018. We collected laboratory data including concentration of serum potassium, plasma activity of renin and aldosterone, and residual blood and/or urine samples of participants who had experienced symptoms/signs of pseudoaldosteronism in the form of increase in blood pressure and occurrence or aggregation of oedema while taking liquorice-containing herbal preparations, and measured GL metabolites using a highly selective liquid chromatography tandem mass spectrometer system. We registered 97 participants (mean age 60 ± 15 years; male:female 14:83). 18ß-glycyrrhetinic acid (GA) was detected in 67 serum samples (median 122 nM, range 5 nM-1.8 µM) and 18ß-glycyrrhetyl-3-O-sulfate (compound 3) in 68 samples (median 239 nM, range 2 nM-4.2 µM). 3-Monoglucuronyl 18ß-glycyrrhetinic acid, 22α-hydroxy-18ß-glycyrrhetyl-3-O-sulfate-30-glucuronide, 22α-hydroxy-18ß-glycyrrhetyl-3-O-sulfate, and GL itself were not or rarely detected. We could not find any correlation between blood pressure or peripheral oedema and serum concentration of GL metabolites. Sulfotransferase 2A1 catalysed the metabolic reaction of GA to compound 3, a major GL metabolite in human blood. High serum concentration of compound 3 was related to lower renin, aldosterone, and potassium levels, suggesting a pathological relationship between compound 3 and liquorice-induced pseudoaldosteronism. This is the first study to identify the association between a novel metabolite, compound 3, and the incidence of pseudoaldosteronism, highlighting it as a promising biomarker.

A Novel Frameshift Mutation of SCNN1G Causing Liddle Syndrome with Normokalemia.

BACKGROUND: Liddle syndrome (LS) is an autosomal dominant disorder caused by single-gene mutations of the epithelial sodium channel (ENaC). It is characterized by early-onset hypertension, spontaneous hypokalemia and low plasma renin and aldosterone concentrations. In this study, we reported an LS pedigree with normokalemia resulting from a novel SCNN1G frameshift mutation. METHODS: Peripheral blood samples were collected from the proband and eight family members for DNA extraction. Next-generation sequencing and Sanger sequencing were performed to identify the SCNN1G mutation. Clinical examinations were used to comprehensively evaluate the phenotypes of two patients. RESULTS: Genetic analysis identified a novel SCNN1G frameshift mutation, p.Arg586Valfs*598, in the proband with LS. This heterozygous frameshift mutation generated a premature stop codon and deleted the vital PY motif of ENaC. The same mutation was present in his elder brother with LS, and his mother without any LS symptoms. Biochemical examination showed normokalemia in the three mutation carriers. The mutation identified was not found in any other family members, 100 hypertensives, or 100 healthy controls. CONCLUSIONS: Our study identified a novel SCNN1G frameshift mutation in a Chinese family with LS, expanding the genetic spectrum of SCNN1G. Genetic testing helped us identify LS with a pathogenic mutation when the genotypes and phenotype were not completely consistent because of the hypokalemia. This case emphasizes that once a proband is diagnosed with LS by genetic testing, family genetic sequencing is necessary for early diagnosis and intervention for other family members, to protect against severe cardiovascular complications.

Risk factors associated with pseudoaldosteronism in patients with chronic hepatitis: A retrospective cohort study.

Glycyrrhizin is used to treat chronic hepatitis, but it also plays an important role in pseudoaldosteronism. Multidrug resistance-associated protein 2 is important for glycyrrhizin excretion. Dysfunction of this transporter increases the serum levels of direct bilirubin, glycyrrhizin and its metabolites. Hence, elevated direct-bilirubin levels could predict the risk of pseudoaldosteronism. This study aimed to evaluate the relationship between elevated direct-bilirubin levels and hypokalaemia, which is the most sensitive marker of pseudoaldosteronism. This retrospective cohort study was conducted in a Japanese university hospital. The occurrence of hypokalaemia is defined as a serum potassium level of ≤3.5 mEq/L after the administration of a glycyrrhizin-containing medication, and a further decline of ≥0.5 mEq/L or an increase of ≥0.5 mEq/L after discontinuing the glycyrrhizin-containing medication was examined in patients with chronic hepatitis between January 2009 and December 2015. This analysis involved 1392 patients, including 596 women. Hepatitis C virus infections were the most common cause of chronic hepatitis in this study. Seventy-nine patients received glycyrrhizin (exposed group; mean age: 60.5 ± 14.2) and 1313 did not receive glycyrrhizin (control group; mean age: 58.3 ± 15.8 years). Synergistic effects of glycyrrhizin-containing medications and elevated direct-bilirubin levels were associated with hypokalaemia. Elevated direct-bilirubin levels and hypoalbuminaemia were associated with hypokalaemia in the exposed group. Older age, female sex, high daily glycyrrhizin dosage, longer duration of glycyrrhizin intake, and potassium-lowering medications were not associated with hypokalaemia after the model adjustment. Elevated direct-bilirubin levels and hypoalbuminaemia may predict pseudoaldosteronism caused by glycyrrhizin.

Diagnostic approach to low-renin hypertension.

Renin-angiotensin-aldosterone system (RAAS) plays a crucial role in maintaining water and electrolytes homoeostasis, and its deregulation contributes to the development of arterial hypertension. Since the historical description of the "classical" RAAS, a dramatic increase in our understanding of the molecular mechanisms underlying the development of both essential and secondary hypertension has occurred. Approximatively 25% of the patients affected by arterial hypertension display low-renin levels, a definition that is largely arbitrary and depends on the investigated population and the specific characteristics of the assay. Most often, low-renin levels are expression of a physiological response to sodium-volume overload, but also a significant number of secondary hereditary or acquired conditions falls within this category. In a context of suppressed renin status, the concomitant examination of plasma aldosterone levels (which can be inappropriately elevated, within the normal range or suppressed) and plasma potassium are essential to formulate a differential diagnosis. To distinguish between the different forms of low-renin hypertension is of fundamental importance to address the patient to the proper clinical management, as each subtype requires a specific and targeted therapy. The present review will discuss the differential diagnosis of the most common medical conditions manifesting with a clinical phenotype of low-renin hypertension, enlightening the novelties in genetics of the familial forms.

Analysis of the genes involved in Mendelian forms of low-renin hypertension in Chinese early-onset hypertensive patients.

BACKGROUND: The study aimed to analyze genes involved in Mendelian forms of low-renin hypertension in Chinese early-onset hypertensive patients. METHODS: A panel of nine genes, namely SCNN1B, SCNN1G, WNK1, WNK4, KLHL3, CUL3, nuclear receptor subfamily 3, group C (NR3C)1, NR3C2, and HSD11B2 were screened by targeted resequencing in 260 Chinese early-onset hypertensive patients. Additionally, exon 13 of both SCNN1B and SCNN1G was sequenced in an independent cohort of 506 Chinese early-onset hypertensive patients. RESULTS: About 81 nonrare and 41 rare variants were, respectively, detected in 221 (85.0%) and 39 (15.0%) patients from the cohort of 260. Of the total 766 patients, those with rare variants in exon 13 of either SCNN1B or SCNN1G had a significantly earlier onset of hypertension (24.7 ±â€Š7.5 vs. 29.0 ±â€Š7.7 years, P = 0.015) and lower serum potassium (3.57 ±â€Š0.59 vs. 3.96 ±â€Š0.41 mmol/l, P = 0.007) than those without rare variants. However, other identified rare variants had no effects on clinical expression. Seven patients (0.91%) were diagnosed with Liddle's syndrome, and the Liddle's syndrome prevalence was 1.72% among the 407 patients with hypertension diagnosed before the age of 30. Genetic screening of the probands' relatives identified 10 additional Liddle's syndrome patients. Treatment of Liddle's syndrome patients with amiloride resulted in normalization of both blood pressure and serum potassium. CONCLUSION: Liddle's syndrome appears to be the most common low-renin Mendelian hypertension in young Chinese hypertensive patients. Sequencing exon 13 of both SCNN1B and SCNN1G is highly advisable in patients with early-onset and low-renin hypertension.

The importance of genetic counseling and genetic screening: a case report of a 16-year-old boy with resistant hypertension and severe hypokalemia.

Liddle's syndrome, an autosomal dominant form of monogenic hypertension, is characterized by salt-sensitive hypertension with early penetrance, hypokalemia, metabolic alkalosis, suppression of plasma rennin activity and aldosterone secretion, and a clear-cut response to epithelial sodium channel blockers but not spironolactone therapy. Here, we describe the case of a 16-year-old boy patient with resistant hypertension (maintain 170-180/100-110 mm Hg after administration four kinds of antiypertensive drugs) and severe hypokalemia. After a series of checks, we exclude primary aldosteronism and renal artery stenosis and other diseases. Finally, the Liddle syndrome was diagnosed because of the DNA sequencing found that the proband's mother and himself had mutations P616L (c.1847 C>T) in the SCNN1B gene. Liddle syndrome should be considered as a cause of hypertension in children or adolescents particularly with suppressed renin activity. Early diagnosis and appropriately tailored treatment avoid complications of long-term unrecognized or inappropriately managed hypertension. Genetic testing has made it possible to make accurate diagnoses and develop tailored therapies for mutation carriers. The role of genetic testing and genetic counseling in establishing the early diagnosis of Liddle's syndrome is important.

Syndromes that Mimic an Excess of Mineralocorticoids.

Pseudohyperaldosteronism is characterized by a clinical picture of hyperaldosteronism with suppression of renin and aldosterone. It can be due to endogenous or exogenous substances that mimic the effector mechanisms of aldosterone, leading not only to alterations of electrolytes and hypertension, but also to an increased inflammatory reaction in several tissues. Enzymatic defects of adrenal steroidogenesis (deficiency of 17α-hydroxylase and 11ß-hydroxylase), mutations of mineralocorticoid receptor (MR) and alterations of expression or saturation of 11-hydroxysteroid dehydrogenase type 2 (apparent mineralocorticoid excess syndrome, Cushing's syndrome, excessive intake of licorice, grapefruits or carbenoxolone) are the main causes of pseudohyperaldosteronism. In these cases treatment with dexamethasone and/or MR-blockers is useful not only to normalize blood pressure and electrolytes, but also to prevent the deleterious effects of prolonged over-activation of MR in epithelial and non-epithelial tissues. Genetic alterations of the sodium channel (Liddle's syndrome) or of the sodium-chloride co-transporter (Gordon's syndrome) cause abnormal sodium and water reabsorption in the distal renal tubules and hypertension. Treatment with amiloride and thiazide diuretics can respectively reverse the clinical picture and the renin aldosterone system. Finally, many other more common situations can lead to an acquired pseudohyperaldosteronism, like the expansion of volume due to exaggerated water and/or sodium intake, and the use of drugs, as contraceptives, corticosteroids, ß-adrenergic agonists and FANS. In conclusion, syndromes or situations that mimic aldosterone excess are not rare and an accurate personal and pharmacological history is mandatory for a correct diagnosis and avoiding unnecessary tests and mistreatments.

Prevalence of Liddle Syndrome Among Young Hypertension Patients of Undetermined Cause in a Chinese Population.

Liddle syndrome, an autosomal dominant form of monogenic hypertension, has been regarded as a rare disorder, which leads to many Liddle syndrome patients being misdiagnosed and experiencing severe complications at an early age. Little is known about the prevalence of Liddle syndrome. In this study, the authors investigated the prevalence of Liddle syndrome confirmed by genetic testing among young hypertension patients of undetermined causes in China. A total of 330 hypertensive patients aged 14 to 40 years after exclusion of common secondary causes of hypertension were enrolled and serum potassium concentrations were measured. Patients with hypokalemia underwent genetic testing of the 13th exon of genes encoding ß and γ subunits of the epithelial sodium channel (ENaC). Diagnosis was established by identification of mutations that destroy the PY motif of ENaC. Five patients were diagnosed with Liddle syndrome (prevalence, 1.52%), as well as 12 of their relatives. These patients with Liddle syndrome presented with an earlier onset of hypertension, a stronger family history of hypertension, and higher blood pressure than those with essential hypertension. All patients had hypokalemia and suppressed plasma renin activity. The results demonstrated that Liddle syndrome is an important etiology of hypertension in this young population. Screening of Liddle syndrome should focus on young hypertension patients, particularly those with early penetrance, hypokalemia, and low renin levels after exclusion of common secondary causes.

3-Monoglucuronyl glycyrrhretinic acid is a possible marker compound related to licorice-induced pseudoaldosteronism.

One of the most common adverse effects of traditional Japanese kampo and traditional Chinese medicine is pseudoaldosteronism caused by licorice. In this review, the authors describe the mechanisms of licorice-induced pseudoaldosteronism by the pharmacokinetics of chemical constituents and its metabolites containing licorice. Glycyrrhizin (GL), the main constituent of licorice, is absorbed as glycyrrhetinic acid (GA), which is a metabolite of GL produced by enterobacteria before its release into the circulation. Circulating GA is metabolized in the liver to become 3-monoglucuronyl-glycyrrhetinic acid (3MGA), which is excreted into the bile via multidrug resistance protein 2 (Mrp2). If Mrp2 function is damaged for some reason, 3MGA is secreted from the liver into the circulation, and excreted into the urine via organic anion transporters expressed at the basolateral side of tubular epithelial cells. Circulating GA cannot be excreted into the urine since GA binds highly to serum albumin and thus does not pass through glomerular filtration and is not a substrate of transporters expressed on tubular epithelial cells. Licorice-induced pseudoaldosteronism develops due to the inhibition of type 2 11ß-hydrosteroid dehydrogenase (11ß-HSD2) which results in the accumulation of cortisol in tubular epithelial cells that activate mineral corticoid receptors to stimulate the excretion of potassium that results in hypokalemia. GA, unlike 3MGA, cannot pass through tubular epithelial cells and cannot inhibit the enzyme in the cells. Therefore, 3MGA may be a genuine causative agent for licorice-induced pseudoaldosteronism. When licorice is used, 3MGA in plasma or urine could function as a marker compound to prevent the adverse effects.

Phenotype-genotype analysis in two Chinese families with Liddle syndrome.

The families with Liddle syndrome show marked phenotypic variation in blood pressure, serum potassium and other clinical manifestations. Here we analyzed the correlation of genotype-phenotype in two Chinese families with Liddle syndrome. The sequence of C-terminus of SCNN1B and SCNN1G were screened in the two families with likely Liddle syndrome. In addition to hypertension and hypokalemia, one of the two pedigrees had sudden death in their family members, so the exons of 428 reported genes-related to cardiovascular diseases were screened as well in the family. A heterozygous ßR566X nonsense mutation was found in the proband-1 in the first pedigree, and the proband's sister and father. They showed mild phenotype with hypertension under control. In contrast, two of the four previous studies report that the mutation causes severe phenotype. A heterozygous ßR597PfrX607 frameshift mutation was identified in the proband-2 in the second pedigree, showing malignant phenotype including resistant hypertension, hypokalemia, higher PRA and plasma angiotensin II levels. Both the proband-2 and the proband-2's father had sudden death in their twenties, but no meaningful mutations were found by screening of the exons in 428 cardiovascular disease-related genes. However, the same mutation has been related to moderate phenotype in previous studies. Our results confirmed that the phenotypes of Liddle syndrome are varied significantly even with the same mutation. The mechanisms why the same mutation causes very different phenotype need to be explored because intervention of these modifiers may change the disease course and prognosis accordingly.

Cerebrovascular consequences of pseudohyperaldosteronism.

The study of mechanistically defined forms of hypertension may provide insight into the relationship between hypertension and stroke. The author retrospectively studied a cohort of 23 individuals with pseudohyperaldosteronism (PHA), a condition associated with pathologic activation of the distal nephron epithelial sodium channel but low renin and aldosterone levels. During a median follow-up of 11 years (range: 1-30), 4 of 23 (17.4%) patients had a cerebrovascular event recorded. Intracranial hemorrhage was not observed in any patient. Cerebrovascular events tended to occur in older patients, minorities, and patients with a later diagnosis of PHA and additional vascular risk factors. In addition to strict blood pressure control, patients with PHA should have early evaluation and treatment of other vascular risk factors to reduce the risk of stroke.

[Hypertension and hypokalemia - a reninoma as the cause of suspected liquorice-induced arterial hypertension]. / Hypertonus und Hypokaliämie - Der Verdacht einer Lakritz-induzierten Hypertonie entpuppt sich als Reninom.

HISTORY AND CLINICAL FINDINGS: A 28-year-old woman presented with dizziness and arterial hypertension. She reported a daily intake of 300 mg liquorice. INVESTIGATIONS: Laboratory analysis revealed hypokalaemia of 2.5 mmol/l and an elevated serum renin activity of 18.6 µg/l/h. Abdominal ultrasound and magnetic resonance imaging showed a circumscribed non-homogenuous round lesion (18 × 22 mm) in the upper third of the right kidney. Selective catheterization of the renal veins revealed increased renin activity in blood from the right renal vein, suggestive of a renin-producing tumor. TREATMENT AND COURSE: Initially antihypertensive therapy with the direct renin receptor antagonist aliskiren was started and followed by a partial nephrectomy, which brought about adequate blood pressure and potassium levels. CONCLUSION: The constellation of hypokalaemia and hypertension often leads to important causes of secondary hypertension such as primary hyperaldosteronism or renal artery stenosis. But less frequent causes should also be considered in the differential diagnoses, such as liquorice overindulgence or reninoma.

The R563Q mutation of the epithelial sodium channel beta-subunit is associated with hypertension.

BACKGROUND: A high prevalence of the R563Q mutation of the epithelial sodium channel ß-subunit has been reported in South African hypertensives compared with unrelated normotensive controls. To delineate the effects of this mutation against a more uniform genetic background, this study investigated the association of the mutation with hypertension within affected kindreds. METHODS: Forty-five index patients and members of their kindreds were studied. Blood pressure, serum potassium and the presence of the R563Q mutation were determined. RESULTS: Of the 136 individuals studied, 89 were heterozygous for the R563Q mutation and 47 homozygous RR. The mean arterial pressure was significantly higher in the R563Q heterozygous group (p = 0.005) after adjusting for gender, race, age and kindred membership. Of the R563Q heterozygous subjects, 71 (80%) had hypertension, while 17 (36%) of the R563Q homozygous RR subjects were hypertensive. Six R563Q heterozygous subjects had hypokalaemia and one R563Q homozygous RR subject had hypokalaemia, but the difference was not statistically significant. Two heterozygous patients had Liddle's syndrome, both occurring during pregnancy. CONCLUSION: The R563Q mutation of ß-ENaC is associated with hypertension within affected kindreds, but does not usually cause the full Liddle's syndrome phenotype.

Pseudoaldosteronism with increased serum cortisol associated with pneumonia, hypouricemia, hypocalcemia, and hypophosphatemia.

We describe here the interesting case of a 73-year-old hypertensive man with pseudoaldosteronism. He had been taking glycyrrhizin at a dose of 75 mg/day for 12 years because of mild liver damage, but had never experienced any previous symptoms associated with hypokalemia. He was referred to our hospital because of hypokalemic tetraparesis and rhabdomyolysis. At that time, we noted mineralocorticoid excess characterized by hypokalemia due to urinary K loss, exacerbation of hypertension due to increased tubular Na reabsorption, metabolic alkalosis, and suppression of both plasma renin activity and plasma aldosterone concentration. His urinary free cortisol excretion rate and the urinary ratio of free cortisol to free cortisone were markedly elevated. Thus we diagnosed pseudoaldosteronism that was related to the long-term use of glycyrrhizin. When he developed pseudoaldosteronism, he also contracted pneumonia, and exhibited elevated levels of serum cortisol and creatinine clearance (CCr) as well as hypouricemia, hypocalcemia, and hypophosphatemia. All normalized after the recovery from pneumonia and the administration of spironolactone. The extracellular volume expansion associated with increased tubular Na reabsorption by the aldosterone-sensitive distal nephron and the resulting increase in CCr caused an inhibition of proximal tubular reabsorption of uric acid, Ca, and inorganic phosphate, leading to their renal loss and therefore hypouricemia, hypocalcemia, and hypophosphatemia, respectively. In this patient, the increased circulating cortisol associated with the stress of inflammation caused by pneumonia triggered the development of pseudoaldosteronism.