Insulin-Like Growth Factor 1 (IGF-1)
Insulin-Like Growth Factor 1 (IGF-1)
    
Number
010363
CPT
84305
Related Information
  • Insulin-Like Growth Factor Binding Protein 1 (IGFBP-1)
    • Synonyms
    IGF-1 ; SM-C/IGF-1 ; Somatomedin-C, Sulfation Factor
    Specimen
    Serum
    Volume
    0.5 mL
    Minimum Volume
    0.2 mL (Note: This volume does not allow for repeat testing.)
    Container
    Red-top tube or gel-barrier tube
    Collection
    Separate serum from cells. Transfer separated serum to a plastic transport tube. Please include the patient's age on the request form.
    Storage Instructions
    Refrigerate
    Causes for Rejection
    Plasma specimen
    Reference IntervalReference Interval - Updated April 30 2007
    See table.1


    Age Male / Female
    (ng/mL)     		Age Male / Female
    (ng/mL) 
    1-7 d ND-26 17 y 193-731 
    8-15 d ND-41 18 y 163-584 
    16 d to 1 y 55-327 19 y 141-483 
    2 y 51-303 20 y 127-424 
    3 y 49-289 21-25 y 116-358 
    4 y 49-283 26-30 y 117-329 
    5 y 50-286 31-35 y 115-307 
    6 y  52-297 36-40 y 109-284 
    7 y 57-316 41-45 y 101-267 
    8 y 64-345 46-50 y 94-252 
    9 y 74-388 51-55 y 87-238 
    10 y 88-452 56-60 y 81-225 
    11 y 111-551 61-65 y 75-212 
    12 y 143-693 66-70 y 69-200 
    13 y 183-850 71-75 y 64-188 
    14 y 220-972 76-80 y 59-177 
    15 y 237-996 81-85 y 55-166 
    16 y 226-903   
    Tanner Stage 
    I 53-332 
    II 84-431 
    III 114- 773 
    IV 217-843 
    V 147-842 
    Use
    Diagnose acromegaly, in which Sm-C and GH are increased; evaluate hypopituitarism and hypothalamic lesions in children (diagnosis of dwarfism and response to therapy). Low levels occur in Laron dwarfism, an entity in which GH is increased.
    Limitations
    Malnutrition will cause low somatomedin-C levels in spite of normal amounts of circulating growth hormone. The Sm-C level does not distinguish pituitary dwarfism from constitutional delay of growth and development.2
    Methodology
    Immunochemiluminometric assay (ICMA)
    Additional Information
    Somatomedin-C is a polypeptide hormone produced by the liver and other tissues, with effect on growth promoting activity and glucose metabolism (insulin-like activity). Somatomedin-C is carried in blood bound to a carrier protein which prolongs its half-life. Its level is therefore more constant than that of growth hormone.

    Low values are described with the extremes of age (first 5-6 years and advanced age), hypopituitarism, malnutrition, diabetes mellitus, Laron dwarfism, hypothyroidism, maternal deprivation syndrome, pubertal delay, cirrhosis, hepatoma, and some cases of short stature and normal GH response to pharmacologic tests.3 Low values may be found with nonfunctioning pituitary tumors, with constitutional delay of growth and development and with anorexia nervosa.2

    High values occur with adolescence, true precocious puberty, pregnancy, obesity, pituitary gigantism, acromegaly and diabetic retinopathy.3

    Since Sm-C is decreased with malnutrition, its concentration provides an index with which to monitor therapy for food deprivation.4

    Footnotes
    1. Nichols Institute Diagnostics (kit manufacturer) Directional Insert.
    2. Kao PC, Abboud CF, and Zimmerman D, “Somatomedin C: An Index of Growth Hormone Activity,” Mayo Clin Proc, 1986, 61(11):908-9.
    3. Cacciari E and Cicognani A, “Somatomedin C in Pediatric Pathophysiology,” Pediatrician, 1987, 14(3):146-53.
    4. Isley WL, Newton G, Dev J, et al, “Somatomedin C in Rheumatoid Arthritis,” N Engl J Med, 1985, 312(18):1197
    References

    Daughaday WH, Salmon WD Jr, Van den Brande JL, et al, “On the Nomenclature of the Somatomedins and Insulin-Like Growth Factors,” J Clin Endocrinol Metab, 1987, 65(5):1075-6.

    DeGroot LJ and Jameson JL, eds, Endocrinology, 4th ed, Philadelphia, PA: WB Saunders Co, 2001, 2257-68.

    Pearson OH, Arafah B, and Brodkey J, “Management of Acromegaly,” Ann Intern Med, 1981, 95(2):225-7.

    Pintor C, Loche S, Cella SG, et al, “A Child With Phenotypic Laron Dwarfism and Normal Somatomedin Levels,” N Engl J Med, 1989, 320(6):376-9.

    Rappaport R, Prevot C, and Brauner R, “Somatomedin-C and Growth in Children With Precocious Puberty: A Study of the Effect of the Level of Growth Hormone Secretion,” J Clin Endocrinol Metab, 1987, 65(6):1112-7.

    Underwood LE and D'Ercole AJ, “Anterior Pituitary Gland and Hypothalamus: Disorders Affecting Anterior Pituitary Function,” Pediatrics, 18th ed, Rudolph AM and Hoffman JI, eds, Norwalk, CT: Appleton & Lange, 1987, 1454-65.

    Watts NB and Keffer JH, “Anterior Pituitary and Hypothalamus,” Practical Endocrinology, 4th ed, Philadelphia, PA: Lea & Febiger, 1989, 11-36.


    Copyright © 2007 by Laboratory Corporation of America® Holdings and Lexi-Comp Inc. All Rights Reserved