Sodium-lithium countertransport and family history of hypertension in childhood.

We have studied the relationship between sodium-lithium countertransport, determined in childhood, and family history of hypertension. Countertransport was measured in healthy children and those with secondary hypertension. There was no significant difference in countertransport between these two groups. In the normal children (n = 52, median age 6.8 years), there was a positive relationship between body mass index and countertransport (rs = 0.34, p < 0.02). A positive relationship between family history of hypertension using a ranked scoring system, and countertransport, not related to age, body mass or blood pressure (n = 34, rs = 0.63, p < 0.001) was also found. There was no significant relationship between intracellular sodium concentration and countertransport. These data confirm that countertransport in normal children is related to body mass index and indicate that a genetic predisposition to primary hypertension marked by sodium-lithium countertransport is identifiable in childhood.