Overnight urinary growth hormone measurement in the diagnosis of acromegaly

Several studies report higher urinary GH excretion in acromegalic patients compared to control subjects. We investigated the diagnostic potential of overnight urinary GH excretion in acromegaly, using a recently developed enzyme-linked immunosorbent assay. Overnight urine samples were obtained from 117 control subjects and nine patients with untreated acromegaly. GH excretion was higher in acromegalic patients compared to control subjects, with geometric mean total overnight values of 46.35 and 5.73 microU respectively. The range for total overnight urinary GH in control subjects was 0.75-21.75 microU and two of the nine patients with untreated acromegaly had GH measurements within this range. Urinary GH measurements were corrected using predictive clinical variables but this resulted in minimal improvement in discrimination between control subjects and acromegalic patients. Lack of complete discrimination between control subjects and acromegalic patients limits the usefulness of a single overnight urinary GH measurement as a screening test for acromegaly.