Renal function may be normal at birth. Proximal tubular dysfunction usually begins at age 3-12 months. Aminoaciduria, proteinuria, phosphaturia, metabolic acidosis, and impaired urine concentrating ability develop subsequently. The severity and the age of onset of the renal tubular dysfunction may be quite variable. Proteinuria is seen frequently but with variability of age of onset and amount of urinary protein loss.
Acidosis is present and of the proximal renal tubular type.
This condition may lead to failure to thrive and recurrent infections. The renal dysfunction may lead to calcium and phosphorus loss, resulting in bone resorption. Bone resorption from long-term loss of phosphorous may lead to rickets and osteomalacia. Generally, tubular phosphate wasting worsens progressively with age. In addition to the renal tubular dysfunction, by the second to third decade, impairment of glomerular filtration and gradual loss of creatinine clearance with progressive renal failure occurs.