PLASMA RENIN ACTIVITY, PLASMA RENIN SUBSTRATE AND URINARY ALDOSTERONE EXCRETION IN THE MENSTRUAL CYCLE IN RELATION TO THE CONCENTRATION OF PROGESTERONE AND OESTROGENS IN THE PLASMA

1972 ◽  
Vol 71 (3) ◽  
pp. 519-529 ◽  
Author(s):  
Johan A. Sundsfjord ◽  
A. Aakvaag

ABSTRACT The relative importance of endogenous progesterone and oestrogens on the rise in plasma renin activity and urinary aldosterone excretion in the luteal phase of the menstrual cycle has been investigated in two groups of young women. One group (luteal group) had plasma progesterone levels of 7–19.5 ng/ml (mean 12.3; sem 1.3) in the second half of the cycle. The other group (luteal failure group) had plasma progesterone levels of 1.5–3.0 ng/ml, (mean 2.1; sem 0.16), on the corresponding days in the second half of the cycle. The plasma oestrogen levels and the oestriol excretion did not differ between the groups at any stage of the cycle. In the luteal group the normal increase in plasma progesterone and plasma oestrogens and in oestriol excretion was accompanied by a doubling in plasma renin activity and urinary aldosterone excretion, whereas the plasma renin substrate levels did not change significantly. In the luteal failure group, no significant increase was found in either plasma renin activity or in urinary aldosterone excretion, in spite of the unchanged plasma oestrogen levels and oestriol excretion. In this group too the plasma renin substrate levels showed no change from the first to the second half of the cycle. It is concluded that the rise in plasma renin activity, plasma angiotensin II concentration and urinary aldosterone excretion in the luteal phase of the normal menstrual cycle is caused by increased progesterone production.

1973 ◽  
Vol 71 (4_Suppl) ◽  
pp. S160 ◽  
Author(s):  
H. Kaulhausen ◽  
W. Oehm ◽  
H. Breuer

1973 ◽  
Vol 73 (3) ◽  
pp. 499-508 ◽  
Author(s):  
Johan A. Sundsfjord ◽  
A. Aakvaag

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.


1991 ◽  
Vol 37 (10) ◽  
pp. 1811-1819 ◽  
Author(s):  
J E Sealey

Abstract Sensitivity and accuracy are essential features of an assay of plasma renin activity (PRA) because the normal concentration of PRA is only 1 pmol/L, and subnormal concentrations have diagnostic relevance. Conditions for blood collection need to be standardized but the conditions are not difficult for outpatients. For routine diagnostic purposes blood should be collected from ambulatory (ideally, untreated) patients on moderate sodium intake. To avoid irreversible cryoactivation of plasma prorenin (which is present in 10-fold greater concentrations than renin), samples should be processed at room temperature and stored completely frozen. Cryoactivation occurs when plasma is liquid at temperatures less than 6 degrees C. PRA is commonly measured with an enzyme kinetic assay in which angiotensin I (Ang I) is formed by the reaction of plasma renin with endogenous renin substrate (angiotensinogen). The Ang I so formed is measured by RIA; results are expressed as an hourly rate (micrograms/L formed per hour). This method, which is provided by most commercial kits, has the potential for unlimited sensitivity because the step for Ang I generation can be prolonged as long as necessary, so that enough Ang I forms to be measured accurately. Unfortunately, that sensitivity is not always exploited. Dilution of plasma during pH adjustment should be kept to a minimum. The Ang I generation step should last at least 3 h. The step should last 18 h for samples with PRA less than 1.0 micrograms/L per hour, to eliminate the errors inherent in the measurement and subtraction of immunoreactive Ang I in the untreated plasma (blank subtraction). These changes actually simplify PRA measurements because they eliminate the need for ice in the clinic and reduce by almost half the number of samples to be assayed by RIA. I also describe the method for measurement of plasma prorenin, which may be an important marker for patients with diabetes mellitus who subsequently develop vascular complications.


1973 ◽  
Vol 45 (s1) ◽  
pp. 295s-299s ◽  
Author(s):  
L. R. Krakoff ◽  
M. Mendlowitz

1. Plasma renin activity and plasma renin substrate were measured by radioimmunoassay of generated angiotensin I in patients with steroid excess syndromes. Significant increases in substrate were observed in patients with Cushing's syndrome, during glucocorticoid therapy and on oral contraceptive agents. Suppression of plasma renin activity occurred only in primary aldosteronism. 2. The Michaelis constant (Km) for the reaction between renin and substrate in plasma at physiological pH (7.4) was also determined. The extent to which elevated plasma renin substrate increases the velocity of angiotensin I formation was then calculated. 3. In patients with Cushing's syndrome, glucocorticoid therapy or oral contraceptive use, elevated renin substrate coupled with failure of suppression of circulating renin results in increased angiotensin I formation.


1975 ◽  
Vol 79 (2) ◽  
pp. 295-300 ◽  
Author(s):  
Fred H. Katz ◽  
Peggy Romfh ◽  
Judith A. Smith ◽  
Ellen F. Roper ◽  
John S. Barnes

ABSTRACT A post-ovulatory peak of fasting supine plasma aldosterone (PA) preceded or accompanied by an increase in plasma renin activity (PRA) was previously reported. These studies have now been extended in 4 additional normal menstruating women and 4 women taking oestrogen-progestogen oral contraceptive pills (OCP), all studied daily for an entire cycle. Distinct luteal phase increases in PRA were seen in the 4 normals, with 2 also demonstrating a rise in PA. Plasma renin substrate (PRS) was usually unvarying throughout the control cycles. The women taking OCP, on the other hand, all had PA and PRA peaks that were apparent by the fourth or fifth day of taking "the pill". All 4 of the treated women had elevated PRS levels but only one woman showed an increase which preceded the elevation of PRA and PA. Plasma cortisol levels were usually above the normal range in the women taking OCP. This study thus indicates that factors other than oestrogen-induced increased substrate production may be responsible for the PRA and PA rise during OCP treatment Such factors might be the natri-uretic effects of oestrogens and progestogens or a direct effect on renin secretion by one of these steroids.


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