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Calcium Clearance and Re-absorption in Patients with 

 Osteoporosis, Renal Stone and Primary Hyperparathyroidism 



D. A. Smith, J. C. Mackenzie 



University Department of Medicine, Gardiner Institute, Western Infirmary, 

 Glasgow, Scotland 



Introduction 



Hypercalciuria is known to occur in patients with hyperparathyroidism and in 

 about 300/0 of patients with renal stone disease. It is not yet known for certain 

 whether there is any difference in calcium reabsorption by the tubules in these 

 conditions. Kleeman et al. (1958) reported that there was decreased clearance of 

 calcium in normal subjects following the administration of parathyroid hormone 

 during calcium infusion. Loken and Gordan (1959), and Gordan et al. (1962) 

 reported that calcium clearance was in fact increased in patients with primary hyper- 

 parathyroidism and decreased in patients with hypoparathyroidism. Bernstein et al. 

 (1963) showed a decreased calcium clearance in patients with hypoparathyroidism 

 given parathyroid hormone during calcium infusion. They also pointed out the 

 importance of associating the calcium clearance with the level of the plasma diffusible 

 calcium. Since some doubt remained, it was decided to investigate this further. 



Patients studied 

 Three groups of patients were studied. Firstly, eight patients with osteoporosis 

 and normal renal function; secondly, nine patients with recurrent renal stone with 

 normal parathyroid function and creatinine clearances; thirdly, eight patients with 

 hyperparathyroidism with normal creatinine clearances. 



Methods 



The calcium : creatinine clearance ratios, and the calcium reabsorbed per 100 ml 

 of filtrate, were estimated in all the patients with renal stone disease and those with 

 osteoporosis before and during the infusion of 10% calcium gluconate in physio- 

 logical saline. 22.5 mg of calcium/kg was infused over 6 hours in six of the osteo- 

 porotic patients and eight patients with renal stone disease. In the remaining two 

 osteoporotic subjects, and one patient with renal stone disease, 15 mg/kg of calcium 

 was infused over 4 hours. Two patients with primary hyperparathyroidism were 

 studied in a similar manner each being given 15 mg of calcium/kg over 4 hours. Urine 

 samples were collected over one hour periods, and blood samples were taken at the 

 midpoints of the urine collections. In a further six patients with primary hyperpara- 



