In a previous work we have found than an association exists between the presence of left ventricular hypertrophy (LVH) and increased circulating levels of insulin-like growth factor I (IGF-I) in essential hypertension. To address whether this association is of pathophysiological relevance the relationship between echocardiographically determined LVH and IGF-I levels was investigated in 49 patients with essential hypertension before and after one year of antihypertensive treatment with different regimens (nonpharmacological measures, bisoprolol, captopril). The control group consisted of 30 normotensive subjects without LVH. Before treatment IGF-I levels were higher (p < 0.05) in hypertensives with LVH, n = 17, (81.3 +/- 14.3 ng/ml) compared with hypertensives without LVH, n = 32, (57.4 +/- 3.9 ng/ml) and controls (61.3 +/- 3.9 ng/ml). A positive correlation was found between IGF-I levels and LVMI in the whole group of hypertensives (r = 0.32, p < 0.05). After one year of treatment hypertensives with initial LVH separated in two subgroups: those in which LVH regressed (n = 10) and those in which LVH persisted (n = 7). A similar diminution of BP was observed in the two subgroups of hypertensives. The IGF-I levels decreased significantly in patients in which LVH regressed (101.6 +/- 21.7 vs. 61.2 +/- 8.5 ng/ml; p < 0.05) and increased slightly in patients in which LVH persisted (51.2 +/- 8.9 vs. 68.5 +/- 7.9 ng/ml). Six patients in which LVH regressed showed a diminution of IGF-I after treatment. These six patients had received captopril as treatment.(ABSTRACT TRUNCATED AT 250 WORDS)