Measured Plasma Aldosterone Research Articles

A simultaneous measurement of plasma aldosterone and deoxycorticosterone by radioimmunoassay

An accurate, precise and sensitive radioimmunoassay method for the simultaneous measurement of deoxycorticosterone (DOC) and aldosterone in human plasma is described. Dichloromethane extraction and Sephadex LH-20 column chromatography provides adequate purification before radioimmunoassay. A hexane pre-extraction is carried out when the sample contains a high progesterone level. Precision, accuracy and recovery were satisfactory. The DOC levels [6.3 ± 4.4 (S.D.) ng/100ml] and aldosterone levels [11.2 ± 10.9 (S.D.) ng/100ml] obtained are in agreement with previously reported values.

Simultaneous Measurement of Plasma Aldosterone and 11-Deoxy-corticosterone (DOC) in Man by Radioimmunoassay

Simultaneous Measurement of Plasma Aldosterone and 11-Deoxy-corticosterone (DOC) in Man by Radioimmunoassay

Plasma aldosterone-renin interrelationships in various forms of essential hypertension: Studies using a rapid assay of plasma aldosterone

Plasma aldosterone measurements using a new radioimmunoassay technique were included in a component analysis of the renin-aldosterone-sodium system. The studies involved 27 normal subjects and 51 patients with essential hypertension characterized by low, normal or high plasma renin activity. Noon plasma aldosterone concentrations closely reflected the state of aldosterone secretion. Thus, in normal subjects, plasma aldosterone values exhibited a relationship to the daily urinary sodium excretion similar to that for urinary aldosterone excretion. Moreover, plasma aldosterone levels and the simultaneously measured plasma renin activity were linearly correlated over a wide range of sodium balance, again pointing to a key role for renin in the control of plasma aldosterone levels. In 21 patients with normal renin essential hypertension, the absolute levels of plasma aldosterone and their relation to plasma renin levels were similar to those observed in normal subjects. In 14 patients with high renin hypertension concurrent plasma aldosterone levels were commensurately elevated. A deflection of this renin-aldosterone interaction observed in some high renin patients appeared consequent to potassium depletion. In contrast, in 14 of 16 patients with low renin essential hypertension, noon plasma aldosterone concentrations, under conditions of normal or moderately high dietary sodium, were higher relative to simultaneous plasma renin activity, resulting in an abnormal plasma aldosterone to renin ratio above 10. This abnormal renin-aldosterone interrelation could prove useful for identifying and further characterizing patients within the low renin hypertension category. In hypertensive patients, plasma aldosterone measurements can be used interchangeably with urinary aldosterone excretion rates but for full meaning they must still be related to an index of sodium balance such as the daily rate of sodium excretion. Moreover, they have special value for short-term studies and for evaluating aldosterone secretion in states of hepatic or renal insufficiency and perhaps in edematous states in which impaired aldosterone metabolism or renal excretion occurs.

Clinical conference: Essential hypertension: new concepts about mechanisms.

Patients with benign essential hypertension in the early uncomplicated stage show several deviations from normal in their renal and adrenal hormonal systems. Levels of plasma aldosterone and progesterone and the secretion rate of 18-hydroxy-11-deoxycorticosterone are shown to be increased, and the metabolic clearance rate of aldosterone is shown to be decreased in these patients. Also, in vitro, the plasma, with added homologous renin, generated angiotensin at rates much higher than normal. Conflicting evidence is presented on plasma aldosterone measurements, including age-dependent decreases in plasma renin and aldosterone. The significance of these findings in pathogenesis of essential hypertension is discussed.

Variations in plasma aldosterone and plasma renin activity throughout the menstrual cycle, with special reference to the pre-ovulatory period.

ABSTRACT The day to day variations in plasma aldosterone and plasma renin activity throughout the menstrual cycle have been investigated in healthy young women. A sensitive and specific radioimmunoassay for the measurement of plasma aldosterone is described. The actual hormone parameters have been correlated with fluctuations in plasma oestradiol and progesterone, and LH has been measured for the determination of time of ovulation. Plasma renin activity and plasma aldosterone gradually increased two to four times from the early follicular to the mid-luteal phase, in accordance with earlier observations. In one woman using a beta adrenergic blocking agent plasma renin activity rose only slightly, whereas a normal rise in plasma aldosterone was noted. Another woman became pregnant during the cycle investigated. In this subject neither plasma renin activity nor plasma aldosterone decreased at the end of the cycle. Plasma aldosterone was almost doubled on the pre-ovulatory day, as compared with the early follicular phase, whereas no significant change in plasma renin activity or plasma renin substrate was found. The cause of this pre-ovulatory increase in plasma aldosterone is not known.

A radioimmunoassay for plasma aldosterone without chromatography.

A radioimmunoassay for plasma aldosterone has been developed which requires no preliminary chromatography. Purification consists of partitioning between cyclohexane and water, and periodate oxidation followed by a sodium hydroxide wash. The antibody affinity for aldosterone-γ-lactone was approximately 5 orders greater than for other interfering steroids. The specificity of the method was confirmed by the finding that additional purification by Sephadex column chromatography did not lower the observed values. Accuracy was confirmed by recovery studies from pooled plasma containing 70.6 pg/ml (recovery = 0.964 added + 74.9 ± 16.3 pg/ml in the range of 0 to 300 pg/ml added). The coefficient of variation for samples assayed on 5–7 different occasions was 10.6 to 14.1%. This assay is a rapid, efficient and accurate means for measuring plasma aldosterone.

RAISED PLASMA ANGIOTENSIN II AND ALDOSTERONE DURING DIETARY SODIUM RESTRICTION IN MAN

Dietary sodium restriction in five normal subjects led to highly significant increases of plasma-angiotensin-II after 2 days. These changes became even more pronounced after 4 and 5 days. There were parallel increases in plasma-aldosterone. Both angiotensin II and aldosterone returned to control values after sodium repletion. There was a significant positive correlation between concurrent measurements of plasma-aldosterone and plasma-angiotensin-II, and a significant inverse correlation between concurrent plasma-aldosterone and serum-sodium. These findings differ from two other studies of similar design, where dietary sodium restriction produced no detectable change in angiotensin II, despite in one instance a pronounced increase in aldosterone similar to that observed in this study.

Episodic secretion of aldosterone in supine man; relationship to cortisol.

ABSTRACT Two normal men had blood taken for measurement of plasma aldosterone, cortisol and renin activity every 30 minutes while supine for 24 hours. Aldosterone secretion occurred in spurts as is true for cortisol. Moreover, peak levels for these two adrenal hormones were synchronous during late sleep and on arising, as was renin activity frequently. However cortisol peaks later in the day were not synchronous with aldosterone.

Aldosterone production and the zona glomerulosa: a genetic study.

The zona glomerulosa of the adrenal gland is well developed in mice of the strain CBA/Fa Cam, but has a relatively poor development in mice of the Peru strain. Nevertheless, there was no significant difference between the strains in rates of aldosterone secretion, estimated both from in vitro incubations and from calculations based on metabolic clearance rates and measured plasma aldosterone concentrations. Plasma concentrations were lower in female mice than in male mice of the same strain, probably because of shorter plasma half-life in female mice. Plasma concentrations were less in CBA mice than in Peru mice of the same sex, probably because of the larger body weights and apparent distribution vol of CBA mice. These findings suggest that the ‘zonal theory’ of the adrenal cortex, according to which the zona glomerulosa simply represents the site of aldosterone production, may require some modification. (Endocrinology 90: 968, 1972)

Measurement of aldosterone secretion rate by radio-immunoassay.

ABSTRACT The radioimmunoassay for the measurement of aldosterone in plasma (1) has been modified to permit measurement of pH 1 hydrolyzable aldosterone in urine and calculation of aldosterone secretion rate. Between 1/100 and 1/150 of a 24-hr urine specimen is necessary for the assay. Following CH2CI2 extraction, pH 1 hydrolysis is carried out for 24 hr. Purification of the aldosterone extract is achieved by 2 paper chromatographies. The technique can also be modified to permit the determination of urinary aldosterone excretion.

Measurement of plasma aldosterone by radioimmunoassay.

A radioimmunoassay for the measurement of plasma aldosterone is described. Aldosterone-3-carboxymethoxime-18,21-diacetate was coupled with rabbit albumin and antibodies produced in rabbits. Five to 20 ml of plasma, with l,2-3H-aldosterone added for recovery, was extracted and purification achieved by one paper chromatography. After 20 min incubation of the antibody-steroid mixture at 37 C, bound and free fractions were separated using Florisil. The mean recovery of 3H-aldosterone, after extraction and chromatography, was 66.3 ± 13.6 (sd)%. The specificity of the method was confirmed by comparing the results obtained with those of the double isotope derivative method on the same plasma samples. The nonspecific blank was 0.088 ± 0.055 ng/sample (mean ±sd). A linear relationship between amounts of aldosterone measured and the size of the samples confirmed accuracy. Coefficients of variation of 14, 13.2 and 10.5% were obtained at levels of 4, 18 and 51 ng of aldosterone/100 ml of plasma. Results on normal individuals were comparable to those in the literature.

Measurement of plasma aldosterone by gas chromatography with electron capture detection.

ABSTRACT The heptafluorobutyrate of tetrahydroaldosterone-γ-lactone was used for the determination of aldosterone in human peripheral plasma by gas chromatography with electron capture detection. The derivative was obtained from plasma as follows: CH2CI2 extraction, cyclohexane/aqueous ethanol partition, HIO4 oxidation to the γ-lactone, thin layer chromatography, enzymatic reduction of the γ-lactone to its tetrahydro derivative, conversion to the heptafluorobutyrate, and thin layer chromatography. The method is relatively simple and sufficiently sensitive to permit assay of aldosterone in normal subjects.