Search

Aluminum toxicity is associated with the development of bone disorders, including fractures, osteopenia, and osteomalacia. Fifty-one infants with a mean (+/- SEM) birth weight of 1007 +/- 34 g, gestational age of 28.5 +/- 0.3 weeks, and serial radiographic documentation at 3, 6, 9, and 12 months for the presence (n = 16) or absence (n = 35) of fractures and/or rickets were studied at the same intervals to determine the serial changes in serum aluminum concentrations and urine aluminum-creatinine ratios. Autopsy bone samples were used to determine the presence of tissue aluminum. Serum aluminum concentrations from 46 infants were stable and similar between groups, with mean values between 15 and 22 micrograms/L. Urine aluminum-creatinine (micrograms per milligram) ratios from 14 infants were higher in infants with fractures and/or rickets (0.26 +/- 0.06 vs 0.12 +/- 0.04) at onset, and rate of decrease in aluminum-creatinine ratio was faster in infants without fractures and/or rickets. All but three infants were tolerating complete enteral feeding at all sampling points. One infant who received aluminum-containing antacid had marked increase in serum aluminum to 83 micrograms/L while urine aluminum-creatinine ratio increased from 0.09 to a peak of 8.53. Vertebrae from three infants at autopsy (full enteral feeding was tolerated for 37 and 41 days in two infants, respectively) showed aluminum deposition in the zone of provisional calcification and along the newly formed trabecula.(ABSTRACT TRUNCATED AT 250 WORDS)

Molar ratios of peptide-bound and free hydroxyproline:creatinine (OHPr:Cr) in urine were measured at 3, 6, 9, and 12 months of age in two groups of very-low-birthweight (VLBW less than or equal to 1500 g) infants. Group A (15 infants) had radiographically confirmed fractures and (or) rickets (F/R); Group B (17 infants) did not. The urinary peptide-bound OHPr:Cr ratio varied widely within groups and was greatest at three months in both groups: A = 0.81 +/- 0.45 and B = 0.55 +/- 0.32 (mean +/- SD). The ratio decreased with increasing postnatal age for each group but was not statistically different between groups throughout the study. The urinary free OHPr:Cr ratio also was greatest at age three months (A = 0.32 +/- 0.15 and B = 0.53 +/- 0.46), rapidly decreasing afterwards, and was not statistically different between groups throughout the study. We conclude that, in VLBW infants, bone turnover as indicated by the urinary peptide-bound OHPr:Cr ratio is highest during early infancy; however, the wide range of values for this ratio suggests that its use alone is not sufficient for detection of F/R in VLBW infants. The rapid decrease in free OHPr:Cr ratio is presumably related to the maturation of renal tubular function.

Fractures and rickets (F/R) often occur in very low birth weight (VLBW less than 1500 g) infants who are acutely ill. However, there are no prospective longitudinal studies of the clinical course of F/R in these infants. In a prospective study of 78 VLBW infants during the first year after birth, radiographic evidence of healing and remodeling of F/R was noted in affected infants (n = 25) concurrent with increased enteral intake and physical growth, and regardless of whether specific orthopedic treatment was initiated. Skeletal maturation as indicated by the development of ossification centers at the wrists was directly related to weight gain, and was similar to term infants by 1 year. No infant had skeletal deformities on follow-up examination. We suggest that VLBW infants with F/R can be managed "conservatively," with emphasis on nutritional intake to achieve weight gain.