Abstract
Transtubular potassium concentration gradient (TTKG) is a useful index of the excretion of potassium in the urine and renal aldosterone bio-activity in the cortical collecting ducts (CCD). Some reports have discussed with respect to TTKG in infant and children, but there have been no previous reports which have evaluated the relation between TTKG and plasma aldosterone concentration (PAC) in neonates. Our objective was to investigate the relation between TTKG and PAC in neonates. We studied TTKG and PAC in premature neonates (n=10) and full-term neonates (n=30 admitted to our hospital from April 1993 to March 1996. In full-term neonates TTKG gradually reached highest level from day 14 to month 1 of age, and reached to the level in adult from 3 to 5 months of age. PAC reached its highest in day 3, and was tendency to decrease gradually after day 3. In premature-neonates TTKG was significantly (p<0.001) higher in day 14 than in day 3, 7, respectively. PAC was high level continuously during 2 weeks of age. Low level TTKG in early neonates shows low sensitivity for renal aldosterone activity, suggests immature function of CCD. Therefore, in infant over 6 months of age TTKG is an easy and sensitive method for estimation of renal aldosteron bio-activity and useful index of function in the CCD.
