Does long-term administration of sodium thiosulphate inhibit progression to renal failure in nephrocalcinosis?

Sir, In a previous communication, about 10 years ago, we presented two patients with erythrocytosis associated with renal tubular acidosis type-I (RTA-I). At that time their work-up had revealed severe metabolic acidosis, alkaline urine, hypokalaemia, hypocitraturia, extensive nephro-calcinosis and increased serum eythropoietin levels, despite abnormally elevated haematocrit values. Therefore, erythro-cytosis was attributed to increased production of erythro-poietin due to localized areas of tissue hypoxia at the areas of nephrocalcinosis w1–3x. One of those patients was lost to follow up a few years later. The other one has attended our outpatient clinic, periodically, for the past 18 years, and is on oral supplementation with the original regimen of sodium bicarbonate, potassium gluconate and sodium thiosulphate. Nephrocalcinosis persisted during this prolonged period of time, without evidence of further calcium deposition. Of particular interest is the fact that renal function remained stable, with serum creatinine fluctuating from 1.8 to 2.1 mgudl.