Serum leptin and ghrelin levels in active and inactive acromegalic patients during an oral glucose tolerance test.
OBJECTIVE
Elevated BMI, fat mass and food intake increases leptin whereas ghrelin is reduced. Ghrelin stimulates growth hormone (GH) secretion. This prospective cross-sectional study was performed to investigate the influence of GH excess on leptin and ghrelin levels at baseline and after glucose load in a large group of acromegalic patients.


METHODS
Leptin, ghrelin, GH, glucose and insulin concentrations were measured during a 3 h OGTT in 17 active, 25 inactive patients without medication (inact) and 8 inactive patients treated successfully with somatostatin analogues (inact-SA). Leptin concentration was measured using an in-house immunofluorometric assay, total serum ghrelin by a commercially available radioimmunoassay. Leptin was corrected for BMI.


RESULTS
During OGTT, no significant difference of baseline, nadir or AUC of leptin/BMI was seen between the groups (baseline leptin/BMI: act: 0.26 microgm(2)/lkg (0.06-0.87); inact: 0.34 microgm(2)/lkg (0.03-1.79); inact-SA: 0.29 microgm(2)/lkg (0.03-1.47). A slight but significant reduction of leptin/BMI occurred in all groups during OGTT (active p<0.001, inact p<0.001, inact-SA p<0.05). Inact had higher ghrelin levels (130 ng/L (69-292) compared to active (102 ng/L (27-232); p=n.s.). Inact-SA had significantly lower ghrelin levels (88 ng/L (72-113)) than inact (p<0.001). There was a significant decline of ghrelin during OGTT in all groups (active p<0.001, inact p<0.001, inact-SA p<0.05).


CONCLUSIONS
GH only has a slight influence on leptin secretion. Ghrelin levels are lowered by GH and SA. Nevertheless, the physiological decreasing effect of glucose load on ghrelin secretion is preserved.
Roemmler
J
J
Medizinische Klinik-Innenstadt, Endocrinology, München, Germany. Josefine.Roemmler@med.unimuenchen.de
Otto
B
B
Steffin
B
B
Bidlingmaier
M
M
Schopohl
J
J
D000172:Acromegaly / Q000097:blood*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D054439:Ghrelin / Q000097:blood*; D005951:Glucose Tolerance Test; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged
D054439:Ghrelin; D020738:Leptin