Myoinositol in Human Neonates: Serum Concentrations and Renal Handling

Abstract

Summary: Free myoinositol (henceforth called inositol) levels were measured in cord blood from newborns, as well as in sera from healthy infants during the first 6 months of life. Renal excretion of inositol by a group of premature infants during their first 2 months of life was also studied. Inositol was measured by a microbiologic assay, using an inositol-requiring yeast, Saccha***omyces carlsbergensis. Inositol concentration in pooled cord ***amples of full term normal newborns was 25 ± 5.3 μg/ml. These levels dropped progressively, reaching adult levels (6.9 μg/ml) by the eighth week of life. Mean concentration of inositol in cord blood of premature neonates was 30 μg/ml.

In premature infants, the inositol content in the urine was always higher than that of the blood; the average urine concentration was 198 μg/ml. Inositol clearance values of premature infants ranged from 0.10–0.79 ml/min and averaged 0.34 ml/min, and were thus lower than the mean inositol clearances of nonuremic normal adults (2.8 ml/min). The total amounts of inositol excreted per day by the premature infants were considerably higher than the amounts ingested. The blood inositol concentrations in infants in this study are similar to those found in adults with unpaired renal function.

The inositol status of the neonate appears to be determined by a balance between the two factors which tend to increase the amount of inositol available, that is, biosynthesis of inositol and ingestion with the formula; and the two factors which decrease the blood level, i.e., kidney maturation with resultant increased inositol clearance and, possibly, renal enzymatic catabolism of inositol.

Speculation: The rat kidney regulates blood inositol concentration via catabolism by an inositol oxidase. Impaired renal function in man is accompanied by raised serum levels of inositol, as well

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD