Low erythrocyte Na+/K+ ratio in children with mild blood pressure elevation and a positive family history of hypertension.

Thirty-seven children aged 6-16 years were studied. Their mothers had a history of previous pre-eclampsia or hypertension in pregnancy on average 10.4 years earlier and had later developed sustained hypertension. Blood pressure in these children was significantly higher than in an age-matched control group (125/71 versus 113/64 mmHg, P less than 0.001). Intracellular Na+ in erythrocytes were not elevated, on the contrary the Na+/K+ ratio was significantly lower than in an age- and sex-matched control group (0.095 versus 0.103, P less than 0.05). Thus women with hypertension in pregnancy who later developed sustained essential hypertension have children with elevated blood pressures at an early age. The observation that the erythrocyte Na+/K+ ratio is reduced in such children suggests that the rise in intracellular Na+ commonly described in essential hypertension is not a primary event.