Calcium Metaboijsm in Old Age 



115 



urinary and faecal Ca occurred when the intake was reduced. 

 In such instances the standard deviation is an exaggeration 

 of the error of the single observations. 



The method of calculation used for estimated requirement 

 rested on a number of assumptions and approximations. 



age 20 



50 



60 



80 years 



wet wt. 

 20 



10 



30o-| mgCii/day 



100 



- 



-100-" 

 age 20 



"true" 

 absorption 



-balance 



30 40 50 60 70 80 years. 



42-68 44-G6 54-67 43-74 51-69 % 



"True" absorption calculated accorcjing to formula (Nicola vsen 

 et ah, 1953, Physiol. Rev., 33, 424): 



(■-r 



Ca (feces) 



a intake -\- Ca secreted 

 *500 nig. used here. 



») 



100 



Fig. 3. Top: Asb content of wbole corp. vertebr.T in men killed 

 by accidents. 



BcUnv: Calcium balances in 38 men. Continued observations 

 over 100-500 days; daily intake about 900 mg. Ca. 



