Antônio Ribeiro-Oliveira Jr, Alexander T Faje and Ariel L Barkan
Measurement of GH after oral glucose tolerance test (OGTT) is used for the diagnosis and surveillance of acromegaly. However, there are major discrepancies between glucose-suppressed GH and plasma IGF1 as indices of biochemical activity of acromegaly in patients with relatively mild GH oversecretion. This study was aimed to assess the performance of OGTT in patients with acromegaly and variable GH outputs.
Forty adults with newly diagnosed, untreated acromegaly (15 with GH >4.3 μg/l and 25 with GH <4.3 μg/l) and elevated IGF1 levels were studied. All underwent Q10 min for 24 h sampling for GH followed by an OGTT.
Postglucose nadir GH (GHn) correlated significantly to 24 h GHn, mean 24 h GH, and baseline GH (P<0.001 for all comparisons). GHn correlated significantly to IGF1 z-scores for the ‘low’ GH group and for the entire group (P<0.0001 for both comparisons), but not for the ‘high’ GH group. None of the patients with mean GH >4.3 μg/l had GHn below 1 μg/l. In contrast, 13 out of 25 patients (52%) with GH <4.3 μg/l showed GHn lower than 1 μg/l, and 7 of them (28%) had GHn lower than 0.4 μg/l. These groups did not differ significantly either for average or for maximal GH suppression in OGTT.
Our data show that suppressibility of GH by glucose in acromegaly is a function of the degree of GH hypersecretion and that OGTT has only limited diagnostic value in patients with biochemically active acromegaly but only mildly increased GH output.
Pouneh K Fazeli, Alexander T Faje, Miriam A Bredella, Sai Polineni, Stephen Russell, Megi Resulaj, Clifford J Rosen and Anne Klibanski
In anorexia nervosa, a psychiatric disease characterized by self-induced starvation and a model of chronic undernutrition, levels of subcutaneous (SAT) and visceral (VAT) adipose tissue are low, whereas marrow adipose tissue (MAT) levels are elevated compared to normal-weight women. The reason for this paradoxical elevation of an adipose tissue depot in starvation is not known. We sought to understand changes in MAT in response to subacute changes in weight and to compare these changes with those of other fat depots and body composition parameters.
Design and methods
We conducted a 12-month longitudinal study including 46 premenopausal women (n = 26 with anorexia nervosa and n = 20 normal-weight controls) with a mean (s.e.m.) age of 28.2 ± 0.8 years. We measured MAT, SAT, VAT and bone mineral density (BMD) at baseline and after 12 months.
At baseline, SAT (P < 0.0001), VAT (P < 0.02) and BMD of the spine and hip (P ≤ 0.0002) were significantly lower and vertebral and metaphyseal MAT (P ≤ 0.001) significantly higher in anorexia nervosa compared to controls. Weight gain over 12 months was associated with increases not only in SAT and VAT, but also epiphyseal MAT (P < 0.03). Changes in epiphyseal MAT were positively associated with changes in BMD (P < 0.03).
In contrast to the steady state, in which MAT levels are higher in anorexia nervosa and MAT and BMD are inversely associated, short-term weight gain is associated with increases in both MAT and BMD. These longitudinal data demonstrate the dynamic nature of this fat depot and provide further evidence of its possible role in mineral metabolism.