The impact of clinical parameters on the pathogenesis of myocardial hypertrophy was examined in 75 male patients with mild essential hypertension. Clinical parameters were age, body weight, sodium excretion (as an estimate for dietary salt intake), systolic and diastolic blood pressure at work, casual blood pressure, resting and stress blood pressure during mental stress test and physical exercise. Left ventricular mass as a parameter for the degree of left ventricular hypertrophy was assessed by 2-D guided M-mode echocardiography. Left ventricular mass correlated with body weight (r = 0.47, p less than 0.002), with body mass index (r = 0.48, p less than 0.001), with systolic blood pressure at the worksite (r = 0.28, p less than or equal to 0.05), and systolic blood pressure at rest (r = 0.35, p less than or equal to 0.01), whereas no correlation was found between casual or stress blood pressure readings during physical exercise and mental stress with the degree of left ventricular hypertrophy. Sodium excretion was related to the end-diastolic diameter of the left ventricle (r = 0.33, p less than or equal to 0.01) and to left ventricular mass (r = 0.35, p less than or equal to 0.01). Multiple regression analysis revealed that sodium excretion over 24 hours, systolic blood pressure at the worksite and body mass index were independent determinants of left ventricular mass. Thus, dietary salt intake was found to modulate the degree of left ventricular hypertrophy independently of the pressure load imposed on the myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)