Effect of sex and assay method on serum concentrations of growth hormone in patients with acromegaly and in healthy controls.
BACKGROUND
Diagnosis and follow-up of acromegaly is based on measurements of serum growth hormone (GH) concentrations during an oral glucose tolerance test (OGTT). A nadir value <1 microg/L is commonly used to define a normal response, but some authors suggest lower cutoff values.


METHODS
To compare the results and subsequent patient classification obtained with 3 GH assays, we obtained basal serum samples from 78 apparently healthy adult controls (43 women and 35 men; median age, 32.5 years) and from 71 treated (44 women and 27 men; median age, 55.2 years) and 7 untreated acromegaly patients (4 women and 3 men; median age, 54.6 years), and OGTT was performed on all patients and on 72 of the 78 controls. GH was determined by 2 immunometric assays-a double monoclonal (AutoDELFIA; Wallac) and a monopolyclonal (Immulite 2000; DPC) assay-and in a limited set of samples by an RIA (Spectria RIA; Orion).


RESULTS
There was a strong correlation (r = 0.995; P < 0.001) between the 2 immunometric methods, but the results obtained with the Immulite 2000 were, on average, 1.4-fold higher than those obtained with the AutoDELFIA. At concentrations around the cutoff (1 microg/L), however, the difference was approximately 2-fold. Overall, the Orion RIA method also showed a good correlation (r = 0.951-0.959) with the other methods, but it did not measure concentrations <2 microg/L. Women had higher basal and OGTT nadir GH concentrations than men.


CONCLUSIONS
Reference intervals should be determined separately for each method, and the need for establishing sex-specific reference values should be investigated.
Markkanen
Helene
H
Department of Clinical Chemistry, Helsinki University Hospital, Helsinki, Finland. helene.markkanen@hus.fi
Pekkarinen
Tuula
T
Välimäki
Matti J
MJ
Alfthan
Henrik
H
Kauppinen-Mäkelin
Ritva
R
Sane
Timo
T
Stenman
Ulf-Håkan
UH
D000172:Acromegaly / Q000097:blood*; D000328:Adult; D005260:Female; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D044967:Serum; D012737:Sex Factors
D019382:Human Growth Hormone