Therapeutic Results in Renal Tubular Osteomalacia 



205 



Case J. C. The chemical findings during treatment were essentially the same as in 

 case M. B. The accretion rate increased on phosphate supplements and increased 

 furthermore on phosphate supplements plus vitamin D. The clinical improvement 



Table 2. Kinetic data in three cases of renal tubular osteomalacia, kg: accretion rate (1 



plasma/day). Si and 5//; exchangeable compartments (1 plasma). k„: urinary clearance rate 



(1 plasma/day), kf: endogenous faecal clearance (1 plasma/day) 



Isotope 



T.C. 



J.C. 



was less dramatic in this case. However, he felt subjectively better. No radiographic 

 changes have been observed so far. 



Discussion 



The accretion rate has been found to be high in untreated renal tubular osteo- 

 malacia when studied with 'I'Ca or ^^Sr (Meltzer et ai, 1960; Lafferty et ai, 1964). 

 In two children treated with 15.000 I.U. of vitamin D, the accretion rate was normal, 

 studied with ^-P (Bauer et ai, 1956). In one adult there was almost no new bone 

 formation when studied with tetracycline labelling (Frame et at., 1965). There was, 

 however, a diffuse deposition of tetracycline in interstitial bone. The conclusion must 

 be that the data observed with ''^Ca or ^^Sr reflects a dift'use deposition in bone rather 

 than true bone formation. The two children studied with ^-P may have had a lower 

 accretion rate in the untreated state. 



On treatment with phosphate supplements the accretion rate increased. This con- 

 trasts to the decrease of the accretion rate found by Lafferty et at. (1964) during 

 treatment with calcium supplements. Since an increased mineral deposition rate is the 

 aim of treatment this favours the treatment with phosphate supplements. 



On treatment with vitamin D, the accretion rate fell in the case described by 

 Meltzer et al. (1960) and after a slight initial increase decreased below the original 

 value after five months of treatment in the case described by Lafferty et al. (1964). 

 In all the cases presented here the accretion rate increased on treatment with phos- 

 phate supplements plus vitamin D. In two cases (M. B. and T. C.) the accretion rate 

 started to decrease after a peak value, but two years after treatment was started, the 

 accretion rate was still not lower than the original value. It may be concluded that 

 this effect is a satisfactory result of treatment. The clinical findings support this 

 conclusion. 



