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Plasma angiotensin II concentrations in the early neonatal period
  1. M Miyawaki,
  2. T Okutani,
  3. R Higuchi,
  4. N Yoshikawa
  1. Division of Perinatal Medicine NICU, Wakayama Medical University, Wakayama City, Wakayama, Japan
  1. Correspondence to:
    Dr Miyawaki
    Division of Perinatal Medicine NICU, Wakayama Medical University, 811-1 Kimiidera, Wakayama City, Wakayama 641-8509, Japan; miyawaki{at}


Background: There have been only a few reports on the renin-angiotensin system in low birthweight infants; in particular, plasma angiotensin II concentrations have not been studied.

Aim: To investigate plasma angiotensin II concentrations in early neonatal infants including low birthweight infants.

Methods: Forty six patients were studied, of whom 14 weighed not less than 2500 g (normal birth weight), 16 weighed less than 2500 g but not less than 1500 g (moderately low birth weight), and 16 weighed less than 1500 g (very low birth weight). Blood samples were collected twice, on day 0 and day 7. Angiotensin II concentration was assayed using an enzyme immunoassay kit with a microplate.

Results: Geometric means of angiotensin II concentrations on day 7 were 19 pg/ml in the normal birthweight group, 28 pg/ml in the moderately low birthweight group, and 76 pg/ml in the very low birthweight group. The concentrations on day 7 in the very low birthweight group were significantly higher than those in the normal birthweight and moderately low birthweight groups (p  =  0.005, p  =  0.031). There were significant correlations between angiotensin II concentration on day 7 and gestational age (rs  =  −0.4, p  =  0.007) and birth weight (rs  =  −0.36, p  =  0.016).

Conclusions: Specific physiological conditions associated with a very low birth weight are thought to be responsible for the increased concentration of angiotensin II on day 7. It is necessary to measure angiotensin II concentration for a longer period after birth and study the factors that could influence it.

  • ACE, angiotensin converting enzyme
  • AII, angiotensin II
  • NBW, normal birth weight
  • MLBW, moderately low birth weight
  • VLBW, very low birth weight
  • low birth weight
  • renin-angiotensin system
  • angiotensin II

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  • Published Online First 4 April 2006

  • Competing interests: none declared