title: Electrolyte excretion in 12-hour urine and in spot urine. Relationship to plasma renin activity and aldosterone concentration in older children.
abstract: Plasma renin activity (PRA) and urinary electrolyte excretion were measured in 137 healthy children aged 6 to 14 years. Plasma aldosterone concentration (PAC) was measured in 52 of the children. Nocturnal 12-hour urine was collected in 110 of the children. Spot urine was collected on two occasions, once just before lying down, once after 90-min supine rest in another 27. Na/K ratio and fractional Na excretion rate (FENa) in 12-hour urine showed a significant inverse correlation with PRA or PAC. Na excretion (mmol/min, mmol/mmol creatinine), Na/K ratio and FENa in the spot urine following 90 min in a supine position showed a significant inverse correlation with PRA or PAC, but they failed to show a significant relationship to PRA or PAC in the spot urine preceding supine rest. A spot urine after 90 min in the supine position is collected easily and hence most appropriate to study the relationship between Na excretion and PRA or PAC clinically.
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000450:Aldosterone / Q000097:blood*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D011187:Posture; D012083:Renin / Q000097:blood*; D012964:Sodium / Q000652:urine*; D013997:Time Factors
chemical_list: D000450:Aldosterone; D012964:Sodium; D012083:Renin