Abstract: A method and kit are provided for determining levels in a biological sample of free IGF-I, IGF-II, or GH ligand that is normally associated in the sample with a binding protein. This method involves contacting the body fluid with an immobilized unlabeled capture reagent and incubating at 4.degree.-10.degree. C. for no greater than about 4 hours to bind the free ligand contained in the body fluid; separating the fluid from the immobilized capture reagent; and measuring the level of free ligand now bound to the capture reagent. This method is particularly useful to determine levels of free IGF-I in serum or plasma.

Abstract: A method is disclosed for producing an anabolic state in a mammal by co-administration by subcutaneous injection of a combination of effective amounts of IGF-I and an IGF binding protein in a defined molar ratio in the absence of growth hormone so as to produce a greater anabolic response in the mammal than that achieved using IGF-I alone in an amount equal to that used for IGF-I in the combination. Preferably, the IGF-I is native-sequence, mature human IGF-I, the binding protein is IGFBP-3, and the mammal is human or a non-human animal of economic importance such as a cow or pig.