Potassium depletion exacerbates essential hypertension.
OBJECTIVE
To determine the effect of potassium depletion on blood pressure in patients with essential hypertension.


METHODS
Double-blind, randomized, crossover study, with each patient serving as his or her own control.


METHODS
Clinical research center at a university hospital.


METHODS
Twelve patients with hypertension.


METHODS
Patients were placed on 10-day isocaloric diets providing a daily potassium intake of either 16 mmol or 96 mmol. The intake of sodium (120 mmol/d) and other minerals was kept constant. On day 11 each patient received a 2-litre isotonic saline infusion over 4 hours.


METHODS
Blood pressure; urinary excretion rates for sodium, potassium, calcium, and phosphorous; glomerular filtration rate; renal plasma flow; and plasma levels of vasoactive hormones.


RESULTS
With low potassium intake, systolic blood pressure increased (P = 0.01) by 7 mm Hg (95% CI, 3 mm Hg to 11 mm Hg) and diastolic pressure increased (P = 0.04) by 6 mm Hg (CI, 1 mm Hg to 11 mm Hg), whereas plasma potassium concentration decreased (P less than 0.001) by 0.8 mmol/L (CI, 0.4 to 1.0 mmol/L). In response to a 2-litre isotonic saline infusion, the mean arterial pressure increased similarly on both diets but reached higher levels on low potassium intake (115 +/- 2 mm Hg compared with 109 +/- 2 mm Hg, P = 0.03). Potassium depletion was associated with a decrease in sodium excretion (83 +/- 6 mmol/d compared with 110 +/- 5 mmol/d, P less than 0.001). Plasma renin activity and plasma aldosterone concentrations also decreased in patients during low potassium intake, but concentrations of arginine vasopressin and atrial natriuretic peptide, glomerular filtration rate, and renal plasma flow were unchanged. Further, low potassium intake increased urinary excretion of calcium and phosphorus and of plasma immunoreactive parathyroid hormone levels.


CONCLUSIONS
Dietary potassium restriction increases blood pressure in patients with essential hypertension. Both sodium retention and calcium depletion may contribute to the increase in blood pressure during potassium depletion.
Krishna
G G
GG
Temple University, Philadelphia, Pennsylvania.
Kapoor
S C
SC
D000328:Adult; D004032:Diet; D004311:Double-Blind Method; D004573:Electrolytes / Q000378:metabolism; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009318:Natriuresis; D011188:Potassium / Q000008:administration & dosage / Q000652:urine; D011191:Potassium Deficiency / Q000150:complications* / Q000378:metabolism; D011897:Random Allocation; D012982:Sodium, Dietary / Q000008:administration & dosage
D004573:Electrolytes; D012982:Sodium, Dietary; D011188:Potassium