Table 2.

Demographic and biochemical data of mineral metabolism in healthy young and old mena

ParameterOld Men (n = 9)Young Men (n = 13)
aReprinted with permission from The American Journal of Physiology (20). Results are given as mean ± SEM. FEPi, fractional excretion of phosphorus; NcAMP, nephrogenous cAMP; GF, glomerular filtrate.
bP < 0.01 versus young men.
cCalculated from the mean value of the intact and maximal PTH; individual values are not available.
dP < 0.05 versus young men.
Age (yr)74 ± 239 ± 1
Body weight (kg)84 ± 278 ± 2
Blood
creatinine (mg/dl)0.96 ± 0.040.92 ± 0.03
ionized calcium (mg/dl)4.84 ± 0.044.84 ± 0.03
phosphorus (mg/dl)2.7 ± 0.1b3.6 ± 0.1
intact PTH (pg/ml)42 ± 4b23 ± 4
calcitriol (pg/ml)37 ± 231 ± 2
25-OHD (ng/ml)20 ± 222 ± 1
PTHmax (pg/ml)158 ± 22137 ± 11
basal/maximal PTH (%)c2316
Urine
creatinine clearance (ml/min)96 ± 6b132 ± 5
calcium (mg/24 h)190 ± 25174 ± 19
phosphorus (mg/24 h)1071 ± 661144 ± 55
FEPi (%)28.2 ± 1.4b16.8 ± 1.2
NcAMP (nmol/100 ml GF)1.83 ± 0.19d1.18 ± 0.16