42 pmol/L) levels, together with normal calciuria and phosphaturia
Hyperphosphatemia stimulates the posterior liberation of fibroblastic growth factor 23 (FGF23) by osteocytes, which inhibits proteins NaPilIa and NaPilIc in the proximal convoluted tubule generating phosphaturia
According to the literature, in transgenic mice increased expression of Klotho in CKD was combined with adequate phosphaturia
, better functional ability of the kidneys and significantly lower degree of calcification compared with wild-type mice with CKD and reduced production of Klotho (Ming Chang Hu et al.
In addition to symptoms of bone pain, muscle weakness and tenderness biochemical studies reveal hypophosphaturia, inappropriate phosphaturia
and raised levels of fibroblastic growth factor(FGF-23).
The other 2 patterns of proximal tubular damage are characteristically seen in patients with clinical Fanconi syndrome exhibiting type II renal tubular acidosis, phosphaturia
, hyperuricemia, aminoaciduria, and glycosuria without hyperglycemia (those associated with cytoplasmic inclusions in proximal tubular cells and those with constipated lysosomes).
The hypocalcemia causes a secondary hyperparathyroidism that leads to phosphaturia
, demineralization of the bones, and eventually osteomalacia.
Both occur due to a complex cascade involving FGF-23 with reduction in phosphaturia
and inhibition of 1-[alpha] hydroxylase.
Tenofovir causes Fanconi's syndrome characterised by proteinuria, phosphaturia
, glycosuria (with normal blood glucose) and bicarbonate wasting.
Hypophosphatemia is the characteristic abnormality in these patients and is attributed to increased secretion of fibroblast growth factor 23 (FGF23), a phosphatonin secreted from dysplastic bone lesions, hence leading to phosphaturia