Parathyroid hypertensive factor predicts efficacy in the treatment of essential hypertension with verapamil

Parathyroid hypertensive factor (PHF) is a circulating hypertensive factor, levels of which are inversely related to renin profile. Given this relationship, it was hypothesized that a PHF level might serve as an alternate predictor of antihypertensive efficacy in hypertensive patients, avoiding the difficulties associated with renin profiling. To test this hypothesis, thirty patients with essential hypertension were placed on 240 mg once daily of a slow release verapamil preparation for a period of one month following a one month run-in period. Results showed an average reduction in mean arterial pressure (MAP)of -7 mmHg (range -5 to - 18) and an average reduction in PHF of -4 mmHg (range 7 to -28). Pre-treatment PHF level correlated with the blood pressure response to verapamil (r = -0.61, p = 0.0004). There was no correlation between any index of renin status and blood pressure. The only other correlation of note was between normalized, ionized calcium and change in blood pressure (r = -0.46, p =0.02). In a forward stepwise multivariate model with MAP as the dependent variable, PHF and normalized, ionized calcium levels were the only biochemical or demographic predictors of response to verapamil. These results suggest that PHF level may be useful in determining the initial choice of antihypertensive agent in hypertensive patients.