Marinobufagenin in essential hypertension and primary aldosteronism: a cardiotonic steroid with clinical and diagnostic implications.
BACKGROUND
The cardiotonic steroid marinobufagenin (MBG) is increasingly suggested to be responsible for some of the cardiovascular injury that has been previously attributed to aldosterone. We examined the clinical correlates of circulating MBG concentrations in hypertensive patients and tested the hypothesis that MBG serves as a reliable diagnostic tool for detecting primary aldosteronism (PA).


METHODS
Plasma MBG concentrations (mean: 0.51±0.25 nmol/l) were measured in the morning fasting samples in 20 patients with PA and 20 essential hypertensive (EH) controls matched for age, sex, body mass index, renal function, urinary sodium and intake of antihypertensive medication (mean age: 51.6 years; 52.2% women).


RESULTS
Overall, plasma MBG was directly correlated with plasma aldosterone, aldosterone to active renin ratio (AARR), diastolic blood pressure, mean carotid intima-media thickness, serum sodium, urinary protein to creatinine ratio and inversely with serum potassium levels. Plasma MBG levels were significantly higher in patients with PA compared to EH (mean: 0.68±0.12 versus 0.35±0.24 nmol/l; p<0.001). ROC analysis yielded a greater AUC for plasma MBG compared to the AARR, PAC and serum potassium levels for detecting PA. Youden's Index analyses yielded the optimal plasma MBG cut-off score for diagnosing PA at >0.49 nmol/l with specificity and sensitivity values of 0.85 and 0.95, respectively, which were higher than those at the optimum AARR cut-off at >3.32 ng/dl/µU/ml.


CONCLUSIONS
In a well-characterized cohort, values of plasma MBG were significantly related to clinical correlates of cardiovascular and renal disease. Plasma MBG emerged as a valuable alternative to the AARR for screening of PA.
Department of Cardiology, Medical University of Graz , Graz , Austria .
Andreas
A
Tomaschitz
Grzegorz
G
Piecha
Eberhard
E
Ritz
Andreas
A
Meinitzer
Josef
J
Haas
Burkert
B
Pieske
Andrzej
A
Wiecek
Jutta
J
Rus-Machan
Hermann
H
Toplak
Winfried
W
März
Nicolas
N
Verheyen
Martin
M
Gaksch
Karin
K
Amrein
Elisabeth
E
Kraigher-Krainer
Astrid
A
Fahrleitner-Pammer
Stefan
S
Pilz
D000450:Aldosterone / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects; D002018:Bufanolides / Q000493:pharmacokinetics* / Q000627:therapeutic use; D059168:Carotid Intima-Media Thickness; D000075222:Essential Hypertension; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D006973:Hypertension / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012083:Renin / Q000097:blood; D012189:Retrospective Studies; D016896:Treatment Outcome; D014662:Vasoconstrictor Agents / Q000493:pharmacokinetics / Q000627:therapeutic use
D002018:Bufanolides; D014662:Vasoconstrictor Agents; C093896:marinobufagenin; D000450:Aldosterone; D012083:Renin
Aldosterone; cardiovascular; hypertension; marinobufagenin; primary aldosteronism