Urinary growth hormone excretion in acromegaly: diagnostic value in mild disease activity

The biochemical assessment of disease activity in acromegaly still presents a problem, especially in treated patients with mild clinical symptoms. We therefore examined the diagnostic value of the measurement of urinary growth hormone (GH) excretion in seventy unselected patients with acromegaly of different activity by comparing it to serum GH, serum insulin-like growth factor I (IGF-I) and clinical activity. There were highly significant, positive correlations between urinary GH and serum GH, serum IGF-I as well as clinical activity score (p < 0.00005), although some overlap between the groups was observed. In seven patients with low serum GH values (< 2.0 micrograms/l) discordant results were found. Two of the seven patients were clinically mildly active, but only IGF-I was either elevated or within the upper normal range; in three other patients who appeared clinically cured either IGF-I (N = 1) or urinary GH (n = 2) alone were increased. In the remaining two patients elevated serum IGF-I and urinary GH as well as activity score suggested disease activity. Thus, in the majority of cases, urinary GH was significantly correlated to the other three parameters, but added little information to that obtained by serum IGF-I. In conclusion, urinary GH measurements in difficult cases may provide a more direct information on the GH status than IGF-I.