Effects of the addition of 10% glucose to a normal saline infusion in normal and hypertensive subjects

Urinary sodium excretion was studied in normotensive and hypertensive subjects during prolonged infusion with normal saline before and after addition of 10% glucose. The addition of glucose did not cause additional expansion of the extracellular fluid compartment. The increased fractional sodium excretion caused by infusion of normal saline was greater in hypertensives than in normotensives and increased after the addition of glucose to a similar degree in both groups. This finding suggests that the 'exaggerated natriuresis' found in hypertensives is not due to an intrinsic alteration in the handling of sodium by the kidney but, rather, to an extrarenal mechanism.