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4416544 
Journal Article 
Relation of plasma phosphate concentration to renal tubular reabsorption of phosphate 
Bijvoet, OL 
1969 
Yes 
Clinical Science
ISSN: 0143-5221
EISSN: 1470-8736 
37 
1 
23-36 
English 
5822530 
1. The relation .between the excretion rate of phosphate and its concentration in plasma was examined in 100 experiments in seventy-seven people before and during an infusion of phosphate.

2. A comparison with the results of an infusion of inulin in three subjects showed that the relation between phosphate excretion and plasma phosphate could be used to calculate the maximum tubular reabsorption rate (Tm) and glomerular filtration rate (GFR).

3. Phosphate Tm was highly correlated with GFR. To remove the contribution of GFR to the variation of Tm, phosphate Tm was expressed in relation to GFR (Tm/GFR). Phosphate Tm/GFR can discriminate between patients with different diseases.

4. Phosphate excretion occurred at concentrations in the plasma less than 60-80% of Tm/GFR and reabsorption attained its maximum only gradually (splay). Splay varied with Tm/GFR, a finding which makes the usual enzymatic explanation of splay untenable.

5. The tubular reabsorption of phosphate in the fasting subject was proportional to the Tm/GFR measured after phosphate infusion. Multiple regression analysis demonstrated that the fasting plasma phosphate concentration was largely determined by the activity of tubular phosphate reabsorption, assessed as Tm/GFR, and to a lesser extent by endogenous load and glomerular filtration rate.