Insulin-like growth factor-I and its binding protein-3 in serum: are they good screening properties for the diagnosis of growth hormone deficiency?

Serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 are simply-determined screening analytes if growth hormone deficiency is suspected. The analysis of growth hormone secretion using standardised stimulation tests and secretion profiles is complicated and expensive in comparison. In retrospect, we have examined the value of insulin-like growth factor-I and its binding protein-3 for the diagnostic clarification of patients with short stature (n = 117). In 39/117 patients growth hormone secretion was investigated as ward patients. Growth hormone deficiency was diagnosed in 10 patients, for 16 patients the diagnosis was neurosecretory dysfunction. For all patients (n = 7) with lowered insulin-like growth factor binding protein-3 and insulin-like growth factor-I values (insulin-like growth factor binding protein-3 < 5th percentile, insulin-like growth factor-I < 10th percentile) a growth hormone disorder was proven. Conversely, however, only 3/10 patients with classical growth hormone deficiency (n = 3) showed a lowering of both analytes. 8/10 patients with classical growth hormone deficiency and 8/16 patients with neurosecretory dysfunction had at least one lowered value. Two patients showed normal values for insulin-like growth factor-I and insulin-like growth factor binding protein-3 despite biochemically proven growth hormone deficiency. The combined determination of insulin-like growth factor-I and insulin-like growth factor binding protein-3 can provide valuable help during preliminary diagnosis of patients of short stature, indicating a disturbance of the growth hormone secretion if the values are lowered. Normal values do not, however, exclude the possibility of a growth hormone deficiency. Inpatient endocrinological testing is indispensible if growth hormone deficiency is suspected.