proximal renal tubular acidosis

proximal renal tubular acidosis (RTA),

an abnormal condition characterized by excessive acid accumulation and bicarbonate excretion. It is caused by the defective reabsorption of bicarbonate in the proximal tubules of the kidney and the resulting flow of excessive bicarbonate into the distal tubules, which normally secrete hydrogen ions. This disruption impedes the formation of titratable acids and ammonium for excretion and ultimately leads to metabolic acidosis. Treatment is the same as for renal tubular acidosis. In primary proximal RTA the defective reabsorption of bicarbonate is the sole causative factor. In secondary proximal RTA the resorptive defect is one of several causative factors and may result from tubular cell damage produced by various disorders, such as Fanconi's syndrome. Compare distal renal tubular acidosis.

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proximal renal tubular acidosis

Renal tubular acidosis type II Nephrology A disorder caused by a partial defect in the secretion of hydrogen ions in the proximal renal tubule, with ↓ reabsorption of HCO₃ from the tubule into the circulation; the net loss of HCO₃ from the body results in metabolic acidosis, accompanied by a loss of glucose, amino acids, phosphate, Ca2+, and potassium in the urine; because of the solute loss, water is also dragged out of the body; the metabolic acidosis results in loss of Ca2+ from bone, and ↑ serum Ca2+; excess serum Ca2+ is excreted by the kidneys, causing a loss of total body Ca2+ resulting in osteomalacia or rickets, impaired growth, skeletal deformities, muscle weakness, kidney stones and nephrocalcinosis associated with the excessive excretion of Ca2+ and phosphate through the kidneys