Serial plasma and urinary aluminum levels and tissue loading in preterm twins

Serial plasma, urinary, and postmortem tissue aluminum levels were determined in 32-week, appropriate-for-gestational-age twins from 45 to 151 days postnatal age. Estimated total aluminum absorptions were 56.7 mg, and 28 mg, twin A and twin B, respectively. At autopsy, Twin A had a hypoplastic right kidney while Twin B had normal kidneys. Mean plasma aluminum levels (twin A, 34.2 micrograms/liter and twin B, 32.3 micrograms/liter) and urinary aluminum levels expressed as aluminum creatinine ratios (twin A, 11.3 and twin B, 8.5) were similar. These levels were elevated compared to normal plasma aluminum levels of 5.1 +/- 3.6 (1 SD) and urinary aluminum creatinine ratios of 0.64 +/- 0.75 (1 SD). Twin A had higher tissue aluminum levels than twin B in all tissues except for brain. Bone and liver aluminum contents for both twins were increased as compared to infants receiving short-term or no parenteral nutrition. We conclude; (1) tissue aluminum loading occurs in infants receiving aluminum-containing solutions, (2) plasma and urinary aluminum levels are poor predictors of tissue aluminum content, (3) enteral solutions may add significant aluminum exposure.