Clinical studies of IGFBP-2 by radioimmunoassay.
A specific radioimmunoassay for human IGFBP-2 was developed using a polyclonal antiserum directed against a partial sequence (hIGFBP-2(176-190)). The tracer was prepared by radioiodination of a [Tyr]o-hIGFBP-2(176-190) derivative. The assay was used to study IGFBP-2 levels in numerous clinical and experimental situations. There was little circadian fluctuations of serum level which showed a marked age-dependence with high levels at birth and senescence and low levels during puberty. Decreased IGFBP-2 levels were present in untreated insulin-dependent diabetes mellitus (IDDM), in acromegaly and during dexamethasone suppression test. GH deficiency, fasting, IGF-I administration to patients with GH receptor deficiency, hepatic failure and insulinomas caused a moderate increase of serum IGFBP-2. Markedly elevated levels were found in chronic renal failure, non-islet cell tumour induced hypoglycemia and leukaemias. The fact that all possible relationships between insulin secretion and IGFBP-2 levels could be identified suggests that insulin is not a major regulator. In general, there was an inverse relationship with serum IGFBP-3 (except IDDM) and IGFBP-2 levels were high in situations where free IGF-II should be expected to be high. The tentative conclusion would therefore be that free IGF-II is a major regulator of circulating IGFBP-2.
Blum
W F
WF
Universitätskinderklinik, Tübingen, Germany.
Horn
N
N
Kratzsch
J
J
Jørgensen
J O
JO
Juul
A
A
Teale
D
D
Mohnike
K
K
Ranke
M B
MB
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004194:Disease; D006801:Humans; D018971:Insulin-Like Growth Factor Binding Protein 2; D011863:Radioimmunoassay; D013002:Somatomedins / Q000378:metabolism*
D002352:Carrier Proteins; D018971:Insulin-Like Growth Factor Binding Protein 2; D013002:Somatomedins