Low birthweight linked to salt sensitivity in children

Low-birthweight children and those born small for their gestational age (SGA) are likely to be salt sensitive, according to study findings published online Aug. 11 in Hypertension.

Giacomo D. Simonetti, MD, and colleagues from Bern University Hospital and University of Bern in Switzerland measured the glomerular filtration rate and salt sensitivity (a mean blood pressure increase of 3 mm Hg or more over 24 hours on a high-salt diet compared with a controlled-salt diet) in 50 white children (mean age 11.3 years). Of these, 35 were of low birthweight and 15 were of normal birthweight, and 25 were SGA and 25 were appropriate for gestational age.

The researchers found that the low-birthweight children had significantly higher baseline blood pressure, a significantly lower glomerular filtration rate, and significantly reduced kidney length and volume compared with children of normal birthweight. In addition, 37% of low-birthweight children and 47% of SGA children had salt sensitivity. There was a significant inverse correlation between salt sensitivity and kidney length but not glomerular filtration rate, the report indicates.

“We conclude that a reduced renal mass in growth-restricted children poses a risk for a lower renal function and for increased salt sensitivity,” Simonetti and colleagues write. “Whether the changes in renal growth are causative or are the consequence of the same abnormal ‘fetal programming’ awaits clarification.”

Simonetti GD, Raio L Surbek D, et al. Salt sensitivity of children with low birthweight.

Hypertension

. 2008;52:625-630