212 



D. A. Smith, J. C. Mackenzie 



thyroidism, the calcium : creatinine clearance ratios and re-absorption of calcium per 

 100 ml of filtrate were estimated during two hour urine collections, a blood sample 

 being taken at the midpoint of the collection. 



Calcium was estimated in plasma, ultrafiltrate and urine by a modification of the 

 Autoanalyzer technique (MacFadyen et al., 1965). Creatinine was estimated by the 

 standard Autoanalyzer technique (Technicon Instruments Limited). Ultrafiltration 

 was performed on fresh serum, transferred to cellophane tubing without exposure to 

 the atmosphere and centrifuged at 37 °C for one hour at 2,000 g in tubes similar to 

 those devised by Toribara et al. (1957). 



Results 



The calcium : creatinine clearance ratios are seen to be directly related to the 

 plasma ultrafilterable calciums in all three groups of patients. In Fig. 1 it can be seen 

 that the calcium : creatinine clearance ratios in patients with ^ primary hyperpara- 



3. 

 ^0.25 



<b 020 



I 



^ 0.15 



Patients with renal catcu/i 



CALCIUM CREATININE 



CLFARANCe RATIO 



ICco/Ccr) 



PATIENTS WITH RENAL CALCULI 



y^0049x-OI67lLOI2 



5.0 6.C 70 8.0 



Piasma ultra-filferable caicium 



9.0 10.0 11.0 

 ''mg per 100 mV 



ULTRA- FILTERABLE CALCIU 



2. The reLxtion between the calcium: creatii 

 ranee ratio and plasma ultrafilterable calcium 

 patients with renal stone (r = .63, P < .001) 



Fig. 1. This shows the relation of calcium; creatinine 

 clearance ration to plasma ultrafilterable calcium in 

 patients with osteoporosis (y = 0.016x — 0.019±0.068; 

 r = .47, P < .0001), primary hyperparathyroidism (y 

 = 0. CIS — 0.065 ±.050; r = .66, P < .001) and renal 

 stone (dots) 



thyroidism are lower than the clearance ratios in the osteoporotic patients, the 95"/o 

 confidence limits of the data being shown by the cross-hatched areas. The differences 

 between the clearances of ultrafilterable calciums between 6 and 9.5 mg^/o are highly 

 significant (P < .001). In the patients with renal stone disease, the calcium: creatinine 

 clearance ratios are significantly higher than in the patients with primary hyper- 



' The data obtained during calcium infusion and the results from the 2 hour urine collections and mni 

 point blood samples were tested seperatcly but found not to differ significantly and the date therefore pooled. 



