Diurnal Variation of Plasma Aldosterone, Cortisol and Renin Activity in Supine Man FRED H. KATZ, PEGGY ROMFH, AND JUDITH A. SMITH, WITH THE TECHNICAL ASSISTANCE OF ELLEN F. ROPER, JOHN S. BARNES, AND JOE B. BOYD Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine and Veterans Administration Hospital, Denver, Colorado ABSTRACT. In order to evaluate episodic secretion of aldosterone over the entire day, plasma aldosterone, renin activity and cortisol were measured every 10 or 30 min in normal human subjects, on both normal and sodium restricted diets, while receiving dexamethasone, on oral contraceptives and in patients with primary aldosteronism, all while supine. Peak levels of aldosterone occurred in the latter part of the sleeping hours and early in the morning in normal subjects on normal sodium diets. Aldosterone was positively correlated with cortisol in all these subjects but with renin in only 3 out of 5. When cortisol secretion was suppressed by dexamethasone, the hours of peak plasma aldo-
T
HE secretion of aldosterone, as detected by short-term fluctuations in plasma levels of this honnone, has recently been demonstrated to be episodic during the course of the day (3), just as is true for the other two major adrenocortical hormones, cortisol and dehydroisoandrosterone (4). In the previous report (3) the major peaks of plasma aldosterone (PA) in 2 supine normal male subjects studied over a 24-hr period were shown to be synchronous with those for plasma cortisol during the major cortisol secretory episodes in the late sleep and early morning hours. This raised the question of the Received June 19, 1974. Supported by grants from The Population Council, New York, grant RR51 from the General Clinical Research Centers Program of the Division of Research Resources, NIH and Veterans Administration Research Project 4844-01. Address reprint requests to Dr. Fred H. Katz, Veterans Administration Hospital, Denver, Colorado 80220. Abstracts of portions of this study have been published in they Clin Invest (1,2) and the Program of the 1973 Endocrine Society Meeting (Abstract No. 369).
sterone levels were the same, and these peak levels were not always related to renin. These data are compatible with a common determinant for ACTH and aldosterone secretion rhythms in supine man. On sodium restriction both subjects tested had statistically significant correlation of aldosterone with both cortisol and renin, and the 2 women on oral contraceptives demonstrated varying patterns of correlation. Patients with primary aldosteronism had either constantly high levels above the normal range or secretory spurts synchronous with cortisol. One of the patients given dexamethasone had no change in his secretion. (J Clin Endocrinol Metab 40: 125, 1975)
role of ACTH in controlling PA rhythm. The purpose of the present study was 1) to extend these observations in normal subjects under various conditions, 2) to investigate the rhythmicity of PA when ACTH and cortisol secretion is abolished, and thereby to more closely identify the role of renin in this rhythm in supine man, and 3) to delimit the relationship, if any, between the cortisol and PA rhythms in primary aldosteronism. PA, plasma cortisol and plasma renin activity (PRA) were measured at frequent intervals throughout the day under controlled conditions. The relationship of the changes in these parameters was then explored by statistical analyses in order to gain further insight into the control of aldosterone secretion. Materials and Methods Healthy, paid volunteers, age 20-29, and patients with primary aldosteronism gave their informed, written consent prior to the initiation of the studies, which had been previously approved by the University's Human Subject Review Committee. Primary aldosteronism was diagnosed in the 4 male patients by the presence of hypertension,
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KATZ, ROMFH AND SMITH
hypokalemia, excretion of aldosterone and/or its 18-glucuronide in the urine at levels exceeding the normal range and hyporeninemia. At the time of study 3 of the patients had low normal serum potassium values (3.5 to 3.9 mEq/1) achieved by dietary potassium supplements or spironolactone administration. One patient, G.M., was receiving spironolactone, 50 mg every 6 hr, during the study and had a serum potassium of 4.5. Three of the patients had adrenal adenomas removed at surgery, with postoperative return of blood pressure to normal, and the fourth, V.Mc, age 70, whose adrenal vein catheterization suggested a right adrenal adenoma, is being successfully treated with spironolactone, 25 mg every 6 hr. Patient R.S., age 14, was studied for 12 hr both before and after the administration of dexamethasone, 0.5 mg every 6 hr, for 3 days. The subjects, both normals and patients, were all given constant diets containing 130 mEq Na and 70 mEq K on the metabolism ward, except for 2 normals who received 10 mEq Na and 70 mEq K. All diets were given for at least 72 hr before the initiation of the repetitive sampling. Blood was sampled every 30 min for 24 hr in all studies, except as otherwise specified, while the patients remained supine. All assays for each hormone in a single subject were performed in the same assay "run." The techniques for blood sampling and measurement of plasma cortisol were the same as those described in the previous report (3). The techniques used for measuring PRA and most of the levels of PA, as well as the coefficients of variation of these methods, have been previously published in detail (5,6). In the last 4 subjects receiving dexamethasone (P.F., J.F., J.Sh. and R.K.), PA was measured by the method of Gomez-Sanchez et al. (7), which gave results similar to the earlier method. Urinary aldosterone was measured as the 18glucuronide by radioimmunoassay in consecutive 12-hr urine collections. The assay is based on that of Wahlen, West and Tyler (8), the complete technical details of which were kindly made available by Dr. West. The final radioimmunoassay step, however, was the same as that used in measuring PA. In some cases the sheep antiserum 088 against aldosterone distributed by the NIH was used for the final radioimmunoassay of PA and urinary aldosterone. That antiserum was similar or greater in sensitivity when used in a final titer of 1:750,000
JCE & M • 1975 Vol 40 • No 1
as that described for a 1:200,000 dilution of our own sheep antiserum (6). Correlation coefficients measuring the linear relationship between aldosterone and renin activity and between aldosterone and cortisol were examined for each subject over the entire 24 hours and for the three periods, midnight to 0830, 0900 to 1600 and 1630 to 2330. The correlation coefficients were computed and tested for significance by standard procedures (see e.g., Dixon and Massey (9). The above mentioned time periods were selected in order to include no more than one meal in each period, since it has been suggested (10) that meals may play a role in adrenocortical secretion. Results
Normal Subjects Three normal subjects, 2 women age 28 and 27 (J.S. and R.K.) and a 20-yr-old man (B.E.), were studied every 30 min for 24 hr while receiving a normal sodium diet. The women were studied during the first half of their menstrual cycles because of the variation in supine PA during the cycle (10). The plasma hormone measurements of one of the women among the 3 normal subjects is shown in Fig. 1. As was true in the 2 men previously reported (3), inspection shows that aldosterone plasma levels usually varied synchronously with those of cortisol. Tables 1 and 2 summarize the PA and PRA levels for the entire 24 hr and for the three separate portions of the day analyzed. In 4 of the 5 normal subjects in our rapid communication (3) and the present paper, studied for 24 hr, the mean PA value was highest in the period from midnight to 0830. In all 5 it was lowest from 1630 to 2330 (Table 1). For PRA (Table 2), though the differences were small, values in 4 out of 5 subjects were highest from 0900 to 1600 and were lowest in all 5 from 1630 to 2330. Correlation analysis (Table 3) showed a highly significant positive correlation between PA and cortisol for all 5 subjects over the entire 24 hr and from midnight to
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DIURNAL VARIATION OF PLASMA ALDOSTERONE j.s.
127
Sleep
18
FIG. 1. Normal supine female subject. Rhythm of PA, PRA and plasma cortisol measured every 30 min over 24 hr. Downward arrows are meals, inverted triangles short trips to bathroom immediately after venipuncture.
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T
HE secretion of aldosterone, as detected by short-term fluctuations in plasma levels of this honnone, has recently been demonstrated to be episodic during the course of the day (3), just as is true for the other two major adrenocortical hormones, cortisol and dehydroisoandrosterone (4). In the previous report (3) the major peaks of plasma aldosterone (PA) in 2 supine normal male subjects studied over a 24-hr period were shown to be synchronous with those for plasma cortisol during the major cortisol secretory episodes in the late sleep and early morning hours. This raised the question of the Received June 19, 1974. Supported by grants from The Population Council, New York, grant RR51 from the General Clinical Research Centers Program of the Division of Research Resources, NIH and Veterans Administration Research Project 4844-01. Address reprint requests to Dr. Fred H. Katz, Veterans Administration Hospital, Denver, Colorado 80220. Abstracts of portions of this study have been published in they Clin Invest (1,2) and the Program of the 1973 Endocrine Society Meeting (Abstract No. 369).
sterone levels were the same, and these peak levels were not always related to renin. These data are compatible with a common determinant for ACTH and aldosterone secretion rhythms in supine man. On sodium restriction both subjects tested had statistically significant correlation of aldosterone with both cortisol and renin, and the 2 women on oral contraceptives demonstrated varying patterns of correlation. Patients with primary aldosteronism had either constantly high levels above the normal range or secretory spurts synchronous with cortisol. One of the patients given dexamethasone had no change in his secretion. (J Clin Endocrinol Metab 40: 125, 1975)
role of ACTH in controlling PA rhythm. The purpose of the present study was 1) to extend these observations in normal subjects under various conditions, 2) to investigate the rhythmicity of PA when ACTH and cortisol secretion is abolished, and thereby to more closely identify the role of renin in this rhythm in supine man, and 3) to delimit the relationship, if any, between the cortisol and PA rhythms in primary aldosteronism. PA, plasma cortisol and plasma renin activity (PRA) were measured at frequent intervals throughout the day under controlled conditions. The relationship of the changes in these parameters was then explored by statistical analyses in order to gain further insight into the control of aldosterone secretion. Materials and Methods Healthy, paid volunteers, age 20-29, and patients with primary aldosteronism gave their informed, written consent prior to the initiation of the studies, which had been previously approved by the University's Human Subject Review Committee. Primary aldosteronism was diagnosed in the 4 male patients by the presence of hypertension,
125
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126
KATZ, ROMFH AND SMITH
hypokalemia, excretion of aldosterone and/or its 18-glucuronide in the urine at levels exceeding the normal range and hyporeninemia. At the time of study 3 of the patients had low normal serum potassium values (3.5 to 3.9 mEq/1) achieved by dietary potassium supplements or spironolactone administration. One patient, G.M., was receiving spironolactone, 50 mg every 6 hr, during the study and had a serum potassium of 4.5. Three of the patients had adrenal adenomas removed at surgery, with postoperative return of blood pressure to normal, and the fourth, V.Mc, age 70, whose adrenal vein catheterization suggested a right adrenal adenoma, is being successfully treated with spironolactone, 25 mg every 6 hr. Patient R.S., age 14, was studied for 12 hr both before and after the administration of dexamethasone, 0.5 mg every 6 hr, for 3 days. The subjects, both normals and patients, were all given constant diets containing 130 mEq Na and 70 mEq K on the metabolism ward, except for 2 normals who received 10 mEq Na and 70 mEq K. All diets were given for at least 72 hr before the initiation of the repetitive sampling. Blood was sampled every 30 min for 24 hr in all studies, except as otherwise specified, while the patients remained supine. All assays for each hormone in a single subject were performed in the same assay "run." The techniques for blood sampling and measurement of plasma cortisol were the same as those described in the previous report (3). The techniques used for measuring PRA and most of the levels of PA, as well as the coefficients of variation of these methods, have been previously published in detail (5,6). In the last 4 subjects receiving dexamethasone (P.F., J.F., J.Sh. and R.K.), PA was measured by the method of Gomez-Sanchez et al. (7), which gave results similar to the earlier method. Urinary aldosterone was measured as the 18glucuronide by radioimmunoassay in consecutive 12-hr urine collections. The assay is based on that of Wahlen, West and Tyler (8), the complete technical details of which were kindly made available by Dr. West. The final radioimmunoassay step, however, was the same as that used in measuring PA. In some cases the sheep antiserum 088 against aldosterone distributed by the NIH was used for the final radioimmunoassay of PA and urinary aldosterone. That antiserum was similar or greater in sensitivity when used in a final titer of 1:750,000
JCE & M • 1975 Vol 40 • No 1
as that described for a 1:200,000 dilution of our own sheep antiserum (6). Correlation coefficients measuring the linear relationship between aldosterone and renin activity and between aldosterone and cortisol were examined for each subject over the entire 24 hours and for the three periods, midnight to 0830, 0900 to 1600 and 1630 to 2330. The correlation coefficients were computed and tested for significance by standard procedures (see e.g., Dixon and Massey (9). The above mentioned time periods were selected in order to include no more than one meal in each period, since it has been suggested (10) that meals may play a role in adrenocortical secretion. Results
Normal Subjects Three normal subjects, 2 women age 28 and 27 (J.S. and R.K.) and a 20-yr-old man (B.E.), were studied every 30 min for 24 hr while receiving a normal sodium diet. The women were studied during the first half of their menstrual cycles because of the variation in supine PA during the cycle (10). The plasma hormone measurements of one of the women among the 3 normal subjects is shown in Fig. 1. As was true in the 2 men previously reported (3), inspection shows that aldosterone plasma levels usually varied synchronously with those of cortisol. Tables 1 and 2 summarize the PA and PRA levels for the entire 24 hr and for the three separate portions of the day analyzed. In 4 of the 5 normal subjects in our rapid communication (3) and the present paper, studied for 24 hr, the mean PA value was highest in the period from midnight to 0830. In all 5 it was lowest from 1630 to 2330 (Table 1). For PRA (Table 2), though the differences were small, values in 4 out of 5 subjects were highest from 0900 to 1600 and were lowest in all 5 from 1630 to 2330. Correlation analysis (Table 3) showed a highly significant positive correlation between PA and cortisol for all 5 subjects over the entire 24 hr and from midnight to
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 12 November 2015. at 13:19 For personal use only. No other uses without permission. . All rights reserved.
DIURNAL VARIATION OF PLASMA ALDOSTERONE j.s.
127
Sleep
18
FIG. 1. Normal supine female subject. Rhythm of PA, PRA and plasma cortisol measured every 30 min over 24 hr. Downward arrows are meals, inverted triangles short trips to bathroom immediately after venipuncture.
16 14 1 12 O
2 io d-
8
150
O 6 V) H 4 oc
o
o 2
100
2.0
400
«.
a Z z
Ul 300 z O
Ul E
E
2 0 0 Ul
.2
0)
O 100 Q
1000 1200 1400 1600 1800 2000 2200 2400 200
400 600
.
0
< 3
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