The effects of five-year growth hormone replacement therapy on muscle strength in elderly hypopituitary patients.
OBJECTIVE
Little is known of the long-term effects of GH replacement therapy on muscle strength in elderly adults with adult onset GH deficiency (GHD). In this study, the effects of 5 years of GH replacement therapy on muscle function were determined in adults over 60 years of age with adult onset GHD.


METHODS
A prospective, open-label, single-centre study. Patients Twenty-six (12 male and 14 female) consecutive hypopituitary adults with adult onset GHD, mean age 65.0 (range 61-74) years.


METHODS
Upper leg muscle strength was measured using a Kin-Com dynamometer. Right and left handgrip strength were measured using an electronic grip force instrument.


RESULTS
The mean insulin-like growth factor-I (IGF-I) SD score increased from -1.10 at baseline to 1.21 at end of the study. Body weight was unchanged during the 5-year study. A sustained increase in lean body mass and a sustained reduction of body fat was observed as measured using dual-energy X-ray absorptiometry (DEXA). The GH replacement therapy induced a sustained increase in isometric (60 degrees ) knee flexor strength. After statistical correction for age and sex variables using observed/predicted value ratios, a sustained increase was also observed in concentric knee flexor strength at an angular velocity of 60 degrees /s, concentric knee extensor strength at 60 degrees /s and 180 degrees /s, and peak right handgrip strength. At baseline, knee flexor strength was 90-96% of predicted, knee extensor strength was 85-87% of predicted, and hand-grip strength was 74-80% of predicted values. At study end, knee flexor strength was 98-106% of predicted, knee extensor strength was 90-100% of predicted, and hand-grip strength was 80-87% of predicted values.


CONCLUSIONS
Elderly patients with adult onset GH deficiency had decreased baseline muscle strength also after correction for age and sex. The 5-year GH replacement therapy normalized knee flexor strength and improved, but did not fully normalize, knee extensor strength and handgrip strength.
Götherström
Galina
G
Research Centre for Endocrinology and Metabolism, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden. galina.gotherstrom@medic.gu.se
Bengtsson
Bengt-Ake
BA
Sunnerhagen
Katharina Stibrant
KS
Johannsson
Gudmundur
G
Svensson
Johan
J
D015502:Absorptiometry, Photon; D000368:Aged; D000704:Analysis of Variance; D001823:Body Composition; D005260:Female; D013006:Growth Hormone / Q000172:deficiency*; D018737:Hand Strength; D006801:Humans; D007018:Hypopituitarism / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007719:Knee Joint; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011446:Prospective Studies; D013718:Tensile Strength / Q000187:drug effects; D013997:Time Factors; D016896:Treatment Outcome
D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone