Silicon and aluminium and their inter-relationship in serum and urine after renal transplantation

The present study was undertaken to establish the relationship between serum and urine silicon and improve renal function and examine whether the increased urinary excretion of aluminium observed after successful renal transplantation was associated with silicon. The changes in silicon and aluminium concentrations in serum and urine were measured in 15 patients for a period of up to 17 days following a first renal transplant. Serum silicon, unlike aluminium, progressively decreased with improving renal function and was significantly positively correlated with serum aluminium but not with the silicon excretion. The urine excretion of aluminium peaked between 4-8 days post-transplantation and was highly significantly positively correlated with urine silicon. The individual patient fractional excretion profiles of aluminium and silicon were variable but in general gave significant positive correlations suggesting that the elements may be cleared by the kidney through a common mechanism or as a chemical species, possibly an hydroxyaluminosilicate. If soluble silicon can chemically interact with aluminium in vivo it may, as in the biosphere, be important in the control of aluminium toxicity and eventual detoxification. Thus, elevated serum silicon concentrations may help to alleviate aluminium toxicity in end-stage renal disease and assist in the rapid clearance of aluminium seen after kidney transplantation.