0021-972x/92/7502-0494503.00/0 Journal of Clinical Endocrinology and Metabolism Copyright 6 1992 by The Endocrine Society
Influence Elderly*
of Vitamin
J. M. QUESADA, R. BOUILLON*
W. COOPMANS,
Vol. 75, No 2 Printed in US A
D on Parathyroid B. RUIZ,
P. ALJAMA,
I. JANS,
Function
in the
AND
Endocrinology and Nephrology Units, Hospital Regional Universitario Reina Sofia (J.M.Q., B.R., P.A.), Cordoba, Spain, and Laboratory for Experimental Medicine and Endocrinology (W.C., I.J., R.B.), Onderwijs en Navorsing, Gasthuisberg, Leuven, Belgium Calcium infusion (1.5 mg/kg body weight over 10 min) decreased serum PTH(l-84) to below normal concentrations in young adults (nadir 14% of basal concentration), whereas the nadir in elderly subjects with secondary hyperparathyroidism was only 32% of basal concentration. The relative decrease was, however, identical in both age groups when simultaneous changes in ionized calcium were taken into account. Basal serum PTH(l-84) in selected elderly subjects (50 + 10 rig/L or 5 f 1 pmol/L, n = 10) decreased significantly (2.7 + 0.9 pmol/L, P < 0.01) after 3 iv injections of 1,25-(OH)sD during 1 week without changes in serum (ionized) calcium. The PTH suppressibility after calcium infusion did not further improve. In conclusion: elderly patients with normal serum creatinine had a small (+30%) but significant increase in intact serum PTH concentration but the mean concentration still remained within the normal range. The PTH secretion remained normally suppressible by acute calcium infusion. Treatment with 1,25-(OH),D decreased basal calcium-PTH setpoint without further additional effects during calcium infusion. (J Clin Endocrinol Metab 75: 494-501,1992)
ABSTRACT
The effect of age and vitamin D status on parathyroid function was studied in 129 healthy subjects between 20 and 89 yr old, with normal serum creatinine (80 yr (n = 17)]. No subject had a history of diseases or of intake of calcium or vitamin D supplements or drugs (including estrogens) known to influence mineral and vitamin D metabolism. The study protocol was approved by the local investigation committee, and informed consent was obtained from all subjects.
Received September 26, 1991. Address all correspondence and requests for reprints to: R. Bouillon, Legendo, Onderwijs en Navorsing, Gasthuisberg, B-3000 Leuven, Belgium. *This work was supported by Grant 3.0044.89 from the Belgian ‘Fonds voor Geneeskundig Wetenschappelijk Onderzoek” and by Medgenix, Fleurus, Belgium.
Study design Venous samples were collected without stasis after an overnight blood samples for ionized calcium were collected in heparinized (Heparin for ionized calcium, Radiometer, Copenhagen, Denmark), immediately analyzed, samples for biochemical measurements
494
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fast, tubes and were
VITAMIN TABLE
1. Biochemical
data on calcium
D AND
PARATHYROID
FUNCTION
40 + 40/41 2.44 + 0.89 k 73 f 1.16 + 109 + 0.86 f 13.28 f 303.3 f 88.4 ?I 1.46 + 0.93 t 94.8 + 147.0 + 7.5 + 2.0 f 43 f 22 + 163 + 16 f
Age (years) Male/female Total calcium (mmol/L) Ionized calcium (mmol/L) Total protein (g/L) Phosphate (mmol/L) Chloride (mmol/L) Magnesium (mmol/L) Urea (mmol/L) Uric acid (mmol/L) Creatinine (pmol/L) Creatinine clearance” (mL/S) Alkaline phosphatase (pkat/L) 250HD (nmol/L) 1,25-(OH)*D (pmol/L) DBP (rmol/L) Free 1,25-(OH)zD (index)* cPTH (rig/L)’ PTH(l-84) (rig/L) IGF-1 (/.dL) Osteocalcin (fig/L) -. ’ Calculated according to Cockroft (20). * Molar ratio of 1,25-(OH),D and DBP, multiplied ‘Expressed in PTH (53-84) fragment equivalent, 2. Correlation
matrix
of data on mineral Calcium
Calcium Ionized calcium Creatinine clearance Alkaline phosphatase 250HD 1,25-(OH)zD cPTH PTH(l-84) IGF-I Statistical
analysis:
ELDERLY
495
metabolism Group 1 (n = 81)
TABLE
IN THE
Group 2 (n = 31)
12
68 + 7 16/15 2.37 k 0.01 0.67 + 0.19 74 t 5 1.03 + 0.13 110 + 8 0.86 + 0.08 14.5 + 6.78 303.3 zk 83.27 97.2 + 8.8 1.0 + 0.23 1.18 + 0.36 44.9 * 34.9 102.3 + 42.4 6.82 f 0.88 1.6 + 0.6 64 f 25 27 + 16 81 + 42 16 + 5
0.1 0.12 5 0.16 4 0.08 3.57 77.3 8.8 0.31 0.2 32.4 42.4 0.6 0.6 14 10 41 8
by 105. to convert
to PTH
(l-84)
multiply
Group 3 (n = 17)
F
84 + 7 918 2.34 + 0.07 0.69 f 0.09 74 f 4 1.06 k 0.09 108 + 4 0.74 f 0.08 14.77 * 3.7 309.3 f 77.3 88.4 It_ 17.68 0.70 + 0.20 1.56 + 0.98 22.4 + 11.5 77.3 + 30 6.88 + 0.32 1.2 t 0.5 94 + 50 29 + 15 78 + 47 18 + 6
12.85 26.82 0.64 10.00 1.39 10.26 1.89 0.04 0.27 65.16 15.39 48.79 12.93 4.68 7.93 32.97 3.16 54.71 0.89
P