Interpretation

Internal exposure, which can be determined from aluminum levels in blood, is a significantly better measure for assessing aluminum-related neurotoxicity. Early signs of neurotoxicity have been reported in plasma concentrations starting at 13 ng/mL, but any elevation must take into account the full clinical history and other clinical signs and symptoms and test results. Previous studies have reported a whole blood to serum ratio for aluminum of approximately 1.7.(1)

The McCarthy(2) and Hernandez(3) describe a biochemical profile that is characteristic of aluminum overload disease in dialysis patients:

-Patients in kidney failure with no signs or symptoms of osteomalacia or encephalopathy usually had serum aluminum below 20 ng/mL and parathyroid hormone (PTH) concentrations above 150 pg/mL, which is typical of secondary hyperparathyroidism.

-Patients with signs and symptoms of osteomalacia or encephalopathy had serum aluminum above 60 ng/mL and PTH concentrations below 50 pg/mL (PTH above the reference range, but low for secondary hyperparathyroidism).

-Patients who had serum aluminum above 60 ng/mL but below 100 ng/mL were identified as candidates for later onset of aluminum-overload disease and required aggressive efforts to reduce their daily aluminum exposure. This was done by switching them from aluminum-containing phosphate binders to calcium-containing phosphate binders, by ensuring that their dialysis water had less than 10 ng/mL of aluminum, and ensuring the albumin used during postdialysis therapy was aluminum free.

Prosthesis wear is known to result in increased circulating concentration of metal ions.(4) A modest increase (6-10 ng/mL) in serum aluminum concentration is likely to be associated with a prosthetic device in good condition. Serum concentrations above 10 ng/mL in a patient with an aluminum-based implant not undergoing dialysis suggest significant prosthesis wear. Increased serum trace element concentrations in the absence of corroborating clinical information do not independently predict prosthesis wear or failure.