QUANTITATIVE HISTOCHEMISTRY OF THE NEPHRON. IV. ALKALINE PHOSPHATASE AND LACTIC DEHYDROGENASE ACTIVITIES IN RENAL TUBULAR DISEASES*

Abstract

Alkaline phosphatase and lactic dehydrogenase (LDH) activities were measured quantitatively in the various anatomical and functional parts of the nephrons from healthy kidneys and from the kidneys of six patients with diseases affecting the renal tubules: familial renal glycosuria, phosphate-losing renal tubular disease, cystine storage disease, and adult Fanconi syndrome. Alkaline phosphatase activity was decreased in the convoluted tubules in all diseases studied except in cystine storage disease. LDH activity was decreased only in two of the three cases of adult Fanconi syndrome and in a child with cystinosis and the Fanconi syndrome. A parallel decrease of both enzymes was observed in two of the patients with adult Fanconi syndrome. The kidneys of three patients with hypophosphatasia were also studied. None had glycosuria. The extremely low level of alkaline phosphatase activity found in the proximal convolutions indicates that this enzyme does not play a key role in glucose reabsorption. This was confirmed by the observation that prolonged phlorhizin-induced glycosuria did not affect the level of alkaline phosphatase activity in the proximal convolution of the dog.