IGF-1 and IGFBP-3 screening for disorders of growth hormone secretion.

AIM

To assess the value of plasma assays of insulin like growth factor (IGF-1) and insulin like growth factor binding protein 3 (IGFBP-3) in the diagnosis of growth hormone disorders in children and adults.

METHODS

Plasma IGF-1 and IGFBP-3 were measured in 47 children referred for the assessment of short stature, 26 adult subjects with hypopituitarism and in 10 adult subjects with acromegaly. Findings were compared with results obtained in 148 normal children and 124 normal adult subjects who comprised the reference range.

RESULTS

Levels of both growth factors and especially IGF-1 are highly age dependent in normal children and adults. Six of 47 short children had growth hormone deficiency and in these cases both IGF-1 and IGFBP-3 were close to the lower limit or below the normal reference range. In young children ( < 10 yr) IGFBP-3 was more informative than IGF-1, distinguishing normal short children from those with growth hormone deficiency. IGF-1 levels were raised in all 10 acromegalic adults, eight of whom had normal levels of IGFBP-3. Similarly growth hormone deficient adults were better identified (23 of 26 patients) by IGF-1 whereas IGFBP-3 was subnormal in only eight cases.

CONCLUSIONS

Provided results are reviewed in relation to an age related normal reference range, both IGF-1 and IGFBP-3 are simple and convenient screening tests for assessing growth hormone deficiency in children. In adults plasma IGF-1 is the diagnostic test for a disorder of growth hormone excess. Low IGF-1 in an adult with a history of pituitary disease strongly suggests the presence of growth hormone deficiency.