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Plasma active renin concentration in children
1Department of Pediatrics, Yamanashi Medical College, Japan.
Insights
Plasma active renin concentration (PARC) is higher in infants and increases with stress or standing. This study validated a reliable method for measuring PARC in children, revealing age-related differences and responses to stimuli.
Area of Science:
- Pediatric Endocrinology
- Renal Physiology
- Biochemical Assays
Background:
- Plasma active renin concentration (PARC) is a key regulator of the renin-angiotensin-aldosterone system.
- Understanding PARC in children is crucial for diagnosing and managing conditions affecting blood pressure and fluid balance.
- Existing methods for measuring PARC have limitations, necessitating reliable alternatives.
Purpose of the Study:
- To validate a renin immunoradiometric assay (IRMA) kit for measuring PARC in children.
- To compare PARC measurements with plasma renin activity (PRA).
- To investigate age-related changes and physiological influences on PARC in pediatric populations.
Main Methods:
- PARC was measured using a renin immunoradiometric assay (IRMA) kit in healthy children aged one month to 16 years.
- PARC was compared with plasma renin activity (PRA) in non-diluted plasma samples.
- PARC levels were analyzed in relation to age, crying state (infants), and body position (upright vs. supine).
Main Results:
- The IRMA method for PARC was found to be simple, reliable, and unaffected by plasma substrate levels or dilution.
- PARC measurements correlated well with PRA in non-diluted samples.
- PARC was significantly higher in infants compared to older children, with marked increases during crying.
- PARC increased significantly in children aged 7-11 years when moving from a supine to an upright position.
Conclusions:
- The validated IRMA method provides a reliable tool for assessing PARC in pediatric studies.
- Infants exhibit higher PARC levels, potentially due to a hyperresponse to acute stress like blood sampling.
- Short-term postural changes (standing) may stimulate active renin release or activation in normal children.
Abstract:
In normal children aged one month to 16 years, the plasma active renin concentration (PARC) was measured with a renin immunoradiometricassay (IRMA) kit, and was compared with plasma renin activity (PRA). The IRMA for renin was found to be independent of the amount of renin substrate and not affected by the dilution of plasma samples, and was therefore proved to be a simple and reliable method. PRA measured in non-diluted plasma samples correlated well with PARC. In the age-related change, PARC in infants was significantly higher than that in older children. In infants, PARC was markedly higher in the crying state than that in the non-crying state. In normal children aged 7 to 11 years, PARC was significantly increased in the upright position compared to the supine position. These findings suggest that a hyperresponse of PARC to acute stress during blood sampling may cause an increase in active renin secretion in infants, and that stimulation by short-term standing may accelerate the activation of inactive renin or the release of active renin.