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Urinary kallikrein excretion in healthy young infants
Insights
This study investigated urinary kallikrein excretion in children. Higher urinary kallikrein excretion correlated positively with sodium and urine volume, but not plasma renin activity.
Area of Science:
- Pediatric Nephrology
- Biochemistry
- Urology
Background:
- Urinary kallikrein plays a role in regulating renal function and electrolyte balance.
- Understanding kallikrein excretion in children is crucial for assessing kidney health.
Purpose of the Study:
- To determine the excretion rate of active and total urinary kallikrein in healthy hospitalized children.
- To investigate the relationship between urinary kallikrein excretion and sodium excretion, urine volume, and plasma renin activity (PRA).
Main Methods:
- Collected 12-hour urine samples and blood from 39 healthy children (aged 3 weeks to 16 years).
- Measured urinary kallikrein activity using synthetic substrate and RIA.
- Determined urinary sodium excretion, urine volume, and plasma renin activity.
Main Results:
- Urinary kallikrein activity ranged from 0-6 µg/24h, representing 10-20% of total kallikrein.
- Significant positive correlations were observed between urinary kallikrein excretion and both sodium excretion and urine volume.
- No significant correlation was found between plasma renin activity and urinary kallikrein excretion.
Conclusions:
- Urinary kallikrein excretion is positively associated with sodium and water excretion in children.
- The excretion rate per kilogram body weight was constant across different age groups.
- Further research may elucidate the precise role of kallikrein in pediatric renal physiology.
Abstract:
Nineteen healthy hospitalized children aged between 3 weeks and 10 years and 20 others aged between one month and 16 years have been investigated for their excretion rate of active and total urinary kallikrein. Twelve hour urine samples were obtained between 7 p.m. and 7 a.m. and blood was drawn at the end of the urine collection period. Urinary kallikrein activity was measured by a synthetic substrate and a direct RIA and urinary sodium excretion, urine volume and plasma renin activity (PRA) were determined. Urinary kallikrein activity was found to be between 0 and 6 micrograms/24h and constituted approximately 10-20% of total kallikrein. When urinary kallikrein excretion rate was correlated with the sodium excretion rate the relationship was found to be positive and significant as was the correlation found between urine volume and urinary kallikrein excretion rate. No correlation could be found between PRA and urinary kallikrein excretion. Although a tendency of higher total kallikrein excretion was seen in older children, the amount excreted from all children per kilogram body weight was constant at 0.8 microgram/kg.