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Growth hormone induced increase in serum IGFBP‐3 level is reversed by anabolic steroids in substance abusing power athletes
Author(s) -
Karila Tuomo,
Koistinen Hannu,
Seppälä Markku,
Koistinen Riitta,
Seppälä Timo
Publication year - 1998
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1046/j.1365-2265.1998.00556.x
Subject(s) - anabolism , medicine , endocrinology , anabolic steroid , hormone , radioimmunoassay , growth hormone , chemistry
OBJECTIVE Body builders may use growth hormone (GH) and anabolic steroids to increase fitness and muscle mass. GH increases serum concentrations of IGF‐I and IGFBP‐3. The combined effects of GH and anabolic androgenic steroids on IGFBP‐3 and IGF‐I levels are not known under authentic substance‐abusing conditions. The aim of this study was to investigate this in substance‐abusing power athletes. DESIGN AND PATIENTS Nine healthy, non‐obese and non‐competing male power athletes, all aggressive substance abusers, used GH and/or anabolic steroids independently of this study. Blood samples were taken both during and between the drug intake. Sixteen substance non‐abusing wrestlers served as controls. MEASUREMENTS Serum IGF‐I concentration was measured by radioimmunoassay and the IGFBP‐3 concentration was measured by two immunofluorometric assays, one detecting proteolytic fragments of IGFBP‐3. The capacity of serum to proteolytically cleave IGFBP‐3 was studied by the proteolysis assay. RESULTS While growth hormone increased the IGFBP‐3 and IGF‐I concentrations, anabolic steroids decreased the same. Concomitant use of growth hormone and anabolic steroids decreased the IGFBP‐3 concentration in five out of six abuse periods in spite of the fact that the IGF‐I concentration remained elevated in four of them. However, in two men who were on low calorie diet both the IGF‐I and IGFBP‐3 concentrations decreased during combined GH/anabolic steroid abuse. No proteolytic fragmentation of IGFBP‐3 was observed. CONCLUSION Massive abuse of anabolic steroids decreases both the basal and GH‐stimulated IGFBP‐3 concentrations, whereas its effects on serum IGF‐I concentration are variable and affected by low calorie diet. This study demonstrates that detection of GH doping by measuring the IGF‐I and/or IGFBP‐3 levels has notable confounding factors.