Uric Acid Excretion in Infancy
Studies of the various renal functions in infants have enabled pediatricians to understand their limited capacity to maintain homeostasis. The neonatal glomerular filtration rate is twenty percent of the normal value when corrected for surface area and tubular immaturity is at an even lower functional level than the glomerulus as evident by a lowered renal threshold of bicarbonate and amino acids, a decreased Tm of glucose and a decreased tubular reabsorption of phosphate (1). The morphological factors for this relatively increased tubular immaturity are the increased surface area of glomerular tissue as compared to tubular tissue and the presence of anatomic heterogeneity especially of the tubules. With increasing age the renal growth increases so that the ratio of kidney size to surface area becomes constant. This increase in kidney mass is largely due to the increased growth of the proximal tubules (2). This is an important factor explaining the relative glomerular tubular preponderance of the foetus and newborn.
KeywordsFractional Excretion Acid Excretion Tubular Reabsorption Kidney Size Uric Acid Excretion
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- 2.Fetterman G.H., Shuplock N.A., Philipp F.S., and Gregg H.S.: The Growth and Maturation of Human Glomeruli and Proximal Convolutions from Term to Adulthood. Studies by Microdissection. Pediatrics 35:601, 1965.Google Scholar