Role of renin and aldosterone in establishment of electrolyte balance in very low birthweight neonates.
Urine sodium, potassium and chloride excretion, plasma renin activity (PRA) and urine aldosterone excretion (UAE) were measured in seven very low birthweight (VLBW) infants during the first 6 weeks after birth. Hyponatraemia was most common, and major changes in urine electrolyte excretion occurred, during the first 2 weeks. These changes in urine electrolyte excretion appeared to relate to improvement in distal tubular function. PRA did not correlate with urine excretion of either aldosterone or electrolytes. However, UAE correlated significantly with fractional sodium-potassium exchange in the distal tubule in a non-linear fashion (P less than 0.001) which suggested a threshold of aldosterone responsiveness between 70 and 100 nmol/24 h per 1.73 m2 UAE. We conclude that in VLBW infants the distal tubule can respond to aldosterone during the first 2-3 weeks, but that the threshold for responsiveness appears to be higher than it is in fullterm infants.
D000450:Aldosterone / Q000652:urine*; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012083:Renin / Q000097:blood*; D012084:Renin-Angiotensin System; D012964:Sodium / Q000378:metabolism; D014883:Water-Electrolyte Imbalance / Q000378:metabolism*
D000450:Aldosterone; D012964:Sodium; D012083:Renin; D011188:Potassium