chapter 5 – birth weight and salt sensitivity of blood pressure

The association between birth weight and blood pressure is well established but at present unexplained. According to the Borst-Guyton concept, chronic hypertension can occur only with a shift in the renal pressurenatriuresis relationship resulting in increased salt sensitivity of blood pressure. We assessed salt sensitivity of blood pressure in a group of 27 healthy adults whose birth weight was available. Birth weight was ascertained from birth certificates or announcements. Salt sensitivity of blood pressure was determined as difference in mean arterial pressure (MAP) between a one-week high-salt (~235 mmol NaCl/day) versus low-salt diet (~55 mmol NaCl/day). Creatinine clearance was estimated according to the formula of Cockcroft and Gault. Birth weight was negatively associated with salt sensitivity of blood pressure (r=-0.60, P=0.002). The creatinine clearance was positively associated with birth weight (r=0.53; p=0.008), but did not influence the association between birth weight and salt sensitivity of blood pressure. Birth weight is associated with salt sensitivity of blood pressure, and this may play a role in the maintenance of elevated blood pressure in individuals with a low birth weight.