0021-972X/784605-0740$02.00/0 Journal of Clinical Endocrinology and Metabolism Copyright © 1978 by The Endocrine Society
Vol. 46, No. 5 Printed in U.S.A.
Calcium-Dependent Aldosterone Secretion in Anephric and Nonnephrectomized Patients on Regular Hemodialysis* K. 0LGAARD, S. MADSEN, M. HAMMER, AND J. LADEFOGED Medical Department P, Division of Nephrology, Rigshospitalet, Copenhagen, Denmark ABSTRACT. The present study was undertaken to investigate the effect of a continuous calcium infusion on the plasma levels of aldosterone, renin activity, and cortisol in six anephric and four nonnephrectomized patients on regular hemodialysis. In both groups, a significant increase in whole blood ionized calcium (bCa2+) was demonstrated. A significant increase in plasma aldosterone (PAC) was noted in the nonnephrectomized patients, in whom the rise in PAC correlated
I
N SOME clinical and experimental situations (1, 2), alterations in plasma aldosterone (PAC) levels cannot be solely explained by those factors which have been commonly accepted in the regulation of the aldosterone secretion from the adrenals, i.e. the renin-angiotensin system (3-5), potassium (6, 7), ACTH (8, 9) and sodium volume changes (10, 11). The presence of a hitherto unidentified factor in the aldosterone regulation, therefore, is often suggested (12-16). Ionized calcium (Ca2+) is involved in many biological secretory processes (17,18) and has been shown to influence the secretion of several hormones such as parathyroid hormone (PTH) (19), insulin (20), catecholamines (21, 22), vasopressin (23-26), LH (27), TSH (28, 29), PRL (30), and ACTH (31). Furthermore, it has been shown that calcium administration inhibits renin release in normal man (32, 33). Despite this inhibitory effect of calcium on renin secretion, a hypertensive effect of calcium administration has clearly been demonstrated (34,35), as well as correlations between blood pressure and hypo- and hypercalcaemia (36-39). Received June 16,1977. Address reprint requests to: K. 01gaard, Medical Department P, Division of Nephrology, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen 0, Denmark. * This study was supported by grants from the Danish Medical Research Council, King Christian X's Foundation, and the Einar Willumsen Memorial Foundation.
with the increase in b-Ca2+. However, in the anephric patients only a smaller and insignificant increase in PAC was found. No significant changes were demonstrated in plasma cortisol or renin activity, nor in potassium or sodium concentrations in either group. It is concluded that ionized calcium influences the plasma levels of aldosterone in uremic patients on regular hemodialysis. (JClin Endocrinol Metab 46: 740, 1978)
Because of the multipotent actions of calcium on the release of different hormones, it seemed obvious to examine whether calcium could be a hitherto unidentified factor of importance in the aldosterone regulation. The study was designed in order to measure PAC, plasma renin activity (PRA), and plasma cortisol (PCC) during a constant calcium infusion in six anephric patients who lacked the renal renin-angiotensin system (40, 41), and to compare the results with those obtained during the same procedure in four nonnephrectomized patients. All patients were subjected to routine hemodialytic therapy with dialytic concentrations of potassium and calcium of 2.0 and 1.5 mmol/liter, respectively. Materials and Methods The mean age in the anephric group (three females and three males) was 44 yr (range, 27-60). The mean time on regular hemodialysis was 53.2 months (range 18-108) and the mean time since bilateral nephrectomy was 44 months (range, 17-105). Nephrological diagnoses included chronic glomerulonephritis (2), malignant nephrosclerosis (2), polycystic kidney disease (1), and congenital abnormality of the kidneys (1). The mean total serum calcium concentration was 2.33 mmol/liter (range, 2.21-2.62) and the mean serum phosphorous was 1.86 mmol/liter (range, 1.01-2.24). One patient had hypertension with a diastolic pressure >105 mm Hg. Four nonnephrectomized males had a mean age
740
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 13 November 2015. at 09:08 For personal use only. No other uses without permission. . All rights reserved.
741
CALCIUM IN ALDOSTERONE REGULATION of 52.5 yr (range, 50-57). Their mean time on regular hemodialysis was 30.5 months (range, 12-71). Three patients had chronic glomerulonephritis and one had polycystic kidney disease. The mean total serum calcium concentration was 2.33 mmol/liter (range, 2.23-2.48) and the mean serum phosphorous concentration was 1.54 mmol/liter (range, 1.19-1.92). Two of the patients had a diastolic blood pressure >105 mm Hg. All patients were hemodialyzed twice a week and received a diet containing on an average 0.8 g protein/kg BW, 50 meq sodium, 50 meq potassium, and approximately 800 ml fluid/day. All were in good condition and none received hormones or any treatment other than dialysis, vitamins, and phosphate binders. Informed consent was obtained from all patients. Calcium infusions were initiated at 0800 h, 3 h before the start of the hemodialysis and 3 days after the previous dialysis. The infusion was prepared by diluting calcium gluconate (Sandoz) with isotonic saline to a final concentration of 2 g calcium/100 ml; the solution was infused at a constant rate of 35 mg calcium/kg BW h"1. All patients were in the supine position throughout the study. After a 30-min preinfusion period, the blood pressure was measured and at 5-min intervals, two venous blood samples were obtained for baseline determinations. At time zero, the infusion was initiated and continued for 120 min. Whole blood calcium concentration (b-Ca2+) and plasma pH were measured at 5-min intervals during the infusion period. In four patients (three anephric and one nonnephrectomized), the investigations were terminated after 90 min due to an increase in b-Ca2+ of more than 0.15 mmol/liter. Fifteen, 30, 60, and 90 or 120 min after the initiation of the
calcium infusion blood samples were obtained for determination of PAC, PRA, PCC, potassium, and sodium. Blood pressure was obtained at the time of blood collection and serum magnesium was determined before the initiation and at the end of the calcium infusion. None of the patients developed clinical symptoms attributable to hypercalcemia during the investigations. PAC was measured by RIA (42). The aldosterone antibody was obtained from the NIAMDD, Bethesda, MD. The PRA was measured by RIA (43), PCC was measured by the competitive proteinbinding technique (44), and b-Ca2+ was measured by a calcium ion-exchange electrode, the Orion model SS-20. The sensitivity of the electrode was 0.14 mmol/liter, the accuracy was linear (r = 0.99), and specificity studies showed no interference from changes in potassium and magnesium concentration, although correction was necessary for changes in the plasma sodium concentration (45). Plasma potassium and sodium were measured by flame photometry. Mean arterial pressure was determined as diastolic pressure plus V6 pulse pressure.
Results Anephric patients The mean basal level of b-Ca2+ was 1.09 mmol/liter (range, 1.04-1.17). During the calcium infusion, a significant increase {P < 0.001) was obtained in b-Ca2+ (Table 1) with a mean rise of 0.18 mmol/liter. As shown in Fig. 1, the increment of b-Ca2+ was comparable in all patients.
TABLE 1. Effect of calcium infusion in six anephric and four nonnephrectomized hemodialysis patients Type of patients Anephric
Minute 0 0 15 30 60 120°
Nonnephrectomized
0 0 5 30 60 120"
Dose of Ca2+ (mg/kg BW) 0 0 8.8 17.6 35.2 70.4
0 0 8.8 17.6 35.2 70.4
Whole blood Ca2+ cone. (mmol/liter) 1.09 ± 1.08 ± 1.13 ± 1.15 ± 1.20 ± 1.27 ±
0.02 0.02 0.02 0.03 0.03 0.04
1.08 ± 1.09 ± 1.14 ± 1.17 ± 1.23 ± 1.30 ±
0.02 0.02 0.02 0.02 0.02 0.02
PAC (pg/ml)
PRA (ng/ml/h)
86 ± 17 93 ± 2 0
0.04 0.07 0.02 0.02 0.05 0.03
± ± ± ± ± ±
0.02 0.02 0.01 0.01 0.03 0.02
11.3 ± 1.2 11.3 ± 1.4 11.0 ± 1.3
4.0 4.3 4.4 4.7 4.8 4.6
± ± ± ± ± ±
2.4 2.6 2.6 2.8 3.1 3.2
109 ± 25 111 ± 28 109 ± 26 89 ± 17 403 393 387 508 926 784
± 56 ± 81 ± 69 ± 41 ± 85 ±85
PCC (jig/100 ml)
Plasma K (mmol/ liter)
Plasma Na (mmol/liter)
10.3 ± 1.1 9.3 ± 1.4 8.9 ± 1.0
6.3 ± 6.4 ± 6.6 ± 6.5 ± 6.5 ± 6.7 ±
0.3 0.3 0.4 0.3 0.3 0.4
137 ± 137 ± 137 ± 137 ± 136 ± 137 ±
1.5 1.5 1.4 1.4 1.4 1.5
11.1 ±0.5 10.3 ± 0.6 9.5 ± 0.8 8.9 ± 0.6 11.9 ± 0.9 14.2 ± 1.9
6.0 6.0 6.2 6.2 6.4 6.4
0.3 0.3 0.4 0.4 0.4 0.3
137 136 136 136 136 137
1.4 1.4 2.1 1.9 2.3 2.1
± ± ± ± ± ±
± ± ± ± ± ±
Values shown are means ± SEM. " Last value, three patients terminated at 90 min. 6 Last value, one patient terminated at 90 min.
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 13 November 2015. at 09:08 For personal use only. No other uses without permission. . All rights reserved.
742
0LGAARD ET AL.
|
g|200
< 0 20o E
•=8I
o ?
.OH
90 2+
FIG. 1. PAC, PCC, and b-Ca during calcium infusion.
120 min.
in six anephric patients
Mean basal PAC level before the infusion was 90 pg/ml (range, 52-174). The range in basal PAC correlated (P < 0.05) to a corresponding range in basal plasma potassium. During the calcium infusion, the three patients with the highest basal PAC levels showed a moderate increase in PAC (Fig. 1), while the three patients with lower basal PAC levels showed only a very slight rise in PAC. The mean increment in PAC in anephric patients (Table 1) was not significant. The basal average mean arterial pressure was 122 mm Hg (range, 75-145). In all anephric patients, the mean arterial pressure increased during the calcium infusion with a mean rise of 17 mmHg. The mean basal PCC was 11.3 jug/100 ml (range, 7.8-16.6). A slight, nonsignificant decrease was demonstrated during the calcium infusion (Fig. 1). The basal PRA was very low and unchanged during the infusion (Table 1). Plasma potassium increased slightly, but insignificantly, during the infusion; pH, plasma sodium, and magnesium concentrations were constant during the investigation period. Nonnephrectomized patients The mean basal level of b-Ca2+ was 1.09 mmol/liter (range, 1.05-1.13). During the calcium infusion, a significant increase (P < 0.001) was obtained in all patients (Table 1) with a mean rise in b-Ca2+ of 0.21 mmol/liter. In one patient, the infusion was stopped after 90 min.
JCE & M • 1978 Vol 46 • No 5
Mean basal PAC was 398 pg/ml (range, 260-579) and calcium infusion resulted in a significant increase (P < 0.001) in all patients. In three patients, the maximal PAC value was obtained after a 60-min infusion and then showed a tendency to decline (Fig. 2). This pattern was also reflected in the mean PAC values (Table 1). The intraindividual increase in PAC correlate with the corresponding rise inb-Ca 2+ (P
Vol. 46, No. 5 Printed in U.S.A.
Calcium-Dependent Aldosterone Secretion in Anephric and Nonnephrectomized Patients on Regular Hemodialysis* K. 0LGAARD, S. MADSEN, M. HAMMER, AND J. LADEFOGED Medical Department P, Division of Nephrology, Rigshospitalet, Copenhagen, Denmark ABSTRACT. The present study was undertaken to investigate the effect of a continuous calcium infusion on the plasma levels of aldosterone, renin activity, and cortisol in six anephric and four nonnephrectomized patients on regular hemodialysis. In both groups, a significant increase in whole blood ionized calcium (bCa2+) was demonstrated. A significant increase in plasma aldosterone (PAC) was noted in the nonnephrectomized patients, in whom the rise in PAC correlated
I
N SOME clinical and experimental situations (1, 2), alterations in plasma aldosterone (PAC) levels cannot be solely explained by those factors which have been commonly accepted in the regulation of the aldosterone secretion from the adrenals, i.e. the renin-angiotensin system (3-5), potassium (6, 7), ACTH (8, 9) and sodium volume changes (10, 11). The presence of a hitherto unidentified factor in the aldosterone regulation, therefore, is often suggested (12-16). Ionized calcium (Ca2+) is involved in many biological secretory processes (17,18) and has been shown to influence the secretion of several hormones such as parathyroid hormone (PTH) (19), insulin (20), catecholamines (21, 22), vasopressin (23-26), LH (27), TSH (28, 29), PRL (30), and ACTH (31). Furthermore, it has been shown that calcium administration inhibits renin release in normal man (32, 33). Despite this inhibitory effect of calcium on renin secretion, a hypertensive effect of calcium administration has clearly been demonstrated (34,35), as well as correlations between blood pressure and hypo- and hypercalcaemia (36-39). Received June 16,1977. Address reprint requests to: K. 01gaard, Medical Department P, Division of Nephrology, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen 0, Denmark. * This study was supported by grants from the Danish Medical Research Council, King Christian X's Foundation, and the Einar Willumsen Memorial Foundation.
with the increase in b-Ca2+. However, in the anephric patients only a smaller and insignificant increase in PAC was found. No significant changes were demonstrated in plasma cortisol or renin activity, nor in potassium or sodium concentrations in either group. It is concluded that ionized calcium influences the plasma levels of aldosterone in uremic patients on regular hemodialysis. (JClin Endocrinol Metab 46: 740, 1978)
Because of the multipotent actions of calcium on the release of different hormones, it seemed obvious to examine whether calcium could be a hitherto unidentified factor of importance in the aldosterone regulation. The study was designed in order to measure PAC, plasma renin activity (PRA), and plasma cortisol (PCC) during a constant calcium infusion in six anephric patients who lacked the renal renin-angiotensin system (40, 41), and to compare the results with those obtained during the same procedure in four nonnephrectomized patients. All patients were subjected to routine hemodialytic therapy with dialytic concentrations of potassium and calcium of 2.0 and 1.5 mmol/liter, respectively. Materials and Methods The mean age in the anephric group (three females and three males) was 44 yr (range, 27-60). The mean time on regular hemodialysis was 53.2 months (range 18-108) and the mean time since bilateral nephrectomy was 44 months (range, 17-105). Nephrological diagnoses included chronic glomerulonephritis (2), malignant nephrosclerosis (2), polycystic kidney disease (1), and congenital abnormality of the kidneys (1). The mean total serum calcium concentration was 2.33 mmol/liter (range, 2.21-2.62) and the mean serum phosphorous was 1.86 mmol/liter (range, 1.01-2.24). One patient had hypertension with a diastolic pressure >105 mm Hg. Four nonnephrectomized males had a mean age
740
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 13 November 2015. at 09:08 For personal use only. No other uses without permission. . All rights reserved.
741
CALCIUM IN ALDOSTERONE REGULATION of 52.5 yr (range, 50-57). Their mean time on regular hemodialysis was 30.5 months (range, 12-71). Three patients had chronic glomerulonephritis and one had polycystic kidney disease. The mean total serum calcium concentration was 2.33 mmol/liter (range, 2.23-2.48) and the mean serum phosphorous concentration was 1.54 mmol/liter (range, 1.19-1.92). Two of the patients had a diastolic blood pressure >105 mm Hg. All patients were hemodialyzed twice a week and received a diet containing on an average 0.8 g protein/kg BW, 50 meq sodium, 50 meq potassium, and approximately 800 ml fluid/day. All were in good condition and none received hormones or any treatment other than dialysis, vitamins, and phosphate binders. Informed consent was obtained from all patients. Calcium infusions were initiated at 0800 h, 3 h before the start of the hemodialysis and 3 days after the previous dialysis. The infusion was prepared by diluting calcium gluconate (Sandoz) with isotonic saline to a final concentration of 2 g calcium/100 ml; the solution was infused at a constant rate of 35 mg calcium/kg BW h"1. All patients were in the supine position throughout the study. After a 30-min preinfusion period, the blood pressure was measured and at 5-min intervals, two venous blood samples were obtained for baseline determinations. At time zero, the infusion was initiated and continued for 120 min. Whole blood calcium concentration (b-Ca2+) and plasma pH were measured at 5-min intervals during the infusion period. In four patients (three anephric and one nonnephrectomized), the investigations were terminated after 90 min due to an increase in b-Ca2+ of more than 0.15 mmol/liter. Fifteen, 30, 60, and 90 or 120 min after the initiation of the
calcium infusion blood samples were obtained for determination of PAC, PRA, PCC, potassium, and sodium. Blood pressure was obtained at the time of blood collection and serum magnesium was determined before the initiation and at the end of the calcium infusion. None of the patients developed clinical symptoms attributable to hypercalcemia during the investigations. PAC was measured by RIA (42). The aldosterone antibody was obtained from the NIAMDD, Bethesda, MD. The PRA was measured by RIA (43), PCC was measured by the competitive proteinbinding technique (44), and b-Ca2+ was measured by a calcium ion-exchange electrode, the Orion model SS-20. The sensitivity of the electrode was 0.14 mmol/liter, the accuracy was linear (r = 0.99), and specificity studies showed no interference from changes in potassium and magnesium concentration, although correction was necessary for changes in the plasma sodium concentration (45). Plasma potassium and sodium were measured by flame photometry. Mean arterial pressure was determined as diastolic pressure plus V6 pulse pressure.
Results Anephric patients The mean basal level of b-Ca2+ was 1.09 mmol/liter (range, 1.04-1.17). During the calcium infusion, a significant increase {P < 0.001) was obtained in b-Ca2+ (Table 1) with a mean rise of 0.18 mmol/liter. As shown in Fig. 1, the increment of b-Ca2+ was comparable in all patients.
TABLE 1. Effect of calcium infusion in six anephric and four nonnephrectomized hemodialysis patients Type of patients Anephric
Minute 0 0 15 30 60 120°
Nonnephrectomized
0 0 5 30 60 120"
Dose of Ca2+ (mg/kg BW) 0 0 8.8 17.6 35.2 70.4
0 0 8.8 17.6 35.2 70.4
Whole blood Ca2+ cone. (mmol/liter) 1.09 ± 1.08 ± 1.13 ± 1.15 ± 1.20 ± 1.27 ±
0.02 0.02 0.02 0.03 0.03 0.04
1.08 ± 1.09 ± 1.14 ± 1.17 ± 1.23 ± 1.30 ±
0.02 0.02 0.02 0.02 0.02 0.02
PAC (pg/ml)
PRA (ng/ml/h)
86 ± 17 93 ± 2 0
0.04 0.07 0.02 0.02 0.05 0.03
± ± ± ± ± ±
0.02 0.02 0.01 0.01 0.03 0.02
11.3 ± 1.2 11.3 ± 1.4 11.0 ± 1.3
4.0 4.3 4.4 4.7 4.8 4.6
± ± ± ± ± ±
2.4 2.6 2.6 2.8 3.1 3.2
109 ± 25 111 ± 28 109 ± 26 89 ± 17 403 393 387 508 926 784
± 56 ± 81 ± 69 ± 41 ± 85 ±85
PCC (jig/100 ml)
Plasma K (mmol/ liter)
Plasma Na (mmol/liter)
10.3 ± 1.1 9.3 ± 1.4 8.9 ± 1.0
6.3 ± 6.4 ± 6.6 ± 6.5 ± 6.5 ± 6.7 ±
0.3 0.3 0.4 0.3 0.3 0.4
137 ± 137 ± 137 ± 137 ± 136 ± 137 ±
1.5 1.5 1.4 1.4 1.4 1.5
11.1 ±0.5 10.3 ± 0.6 9.5 ± 0.8 8.9 ± 0.6 11.9 ± 0.9 14.2 ± 1.9
6.0 6.0 6.2 6.2 6.4 6.4
0.3 0.3 0.4 0.4 0.4 0.3
137 136 136 136 136 137
1.4 1.4 2.1 1.9 2.3 2.1
± ± ± ± ± ±
± ± ± ± ± ±
Values shown are means ± SEM. " Last value, three patients terminated at 90 min. 6 Last value, one patient terminated at 90 min.
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 13 November 2015. at 09:08 For personal use only. No other uses without permission. . All rights reserved.
742
0LGAARD ET AL.
|
g|200
< 0 20o E
•=8I
o ?
.OH
90 2+
FIG. 1. PAC, PCC, and b-Ca during calcium infusion.
120 min.
in six anephric patients
Mean basal PAC level before the infusion was 90 pg/ml (range, 52-174). The range in basal PAC correlated (P < 0.05) to a corresponding range in basal plasma potassium. During the calcium infusion, the three patients with the highest basal PAC levels showed a moderate increase in PAC (Fig. 1), while the three patients with lower basal PAC levels showed only a very slight rise in PAC. The mean increment in PAC in anephric patients (Table 1) was not significant. The basal average mean arterial pressure was 122 mm Hg (range, 75-145). In all anephric patients, the mean arterial pressure increased during the calcium infusion with a mean rise of 17 mmHg. The mean basal PCC was 11.3 jug/100 ml (range, 7.8-16.6). A slight, nonsignificant decrease was demonstrated during the calcium infusion (Fig. 1). The basal PRA was very low and unchanged during the infusion (Table 1). Plasma potassium increased slightly, but insignificantly, during the infusion; pH, plasma sodium, and magnesium concentrations were constant during the investigation period. Nonnephrectomized patients The mean basal level of b-Ca2+ was 1.09 mmol/liter (range, 1.05-1.13). During the calcium infusion, a significant increase (P < 0.001) was obtained in all patients (Table 1) with a mean rise in b-Ca2+ of 0.21 mmol/liter. In one patient, the infusion was stopped after 90 min.
JCE & M • 1978 Vol 46 • No 5
Mean basal PAC was 398 pg/ml (range, 260-579) and calcium infusion resulted in a significant increase (P < 0.001) in all patients. In three patients, the maximal PAC value was obtained after a 60-min infusion and then showed a tendency to decline (Fig. 2). This pattern was also reflected in the mean PAC values (Table 1). The intraindividual increase in PAC correlate with the corresponding rise inb-Ca 2+ (P
