It is well established that chronic excess of glucocorticoids has negative effects on bone and collagen turnover, and that secondary osteoporosis is a known clinical complication of endogenous Cushing's syndrome (CS). The aim of the present study was to evaluate bone dimension and bone mineral content in relation to biochemical markers of bone and collagen turnover, in a consecutive series of 23 patients with endogenous CS (18 with pituitary adenoma and 5 with adrenal tumor; 17 women, 6 men; mean age 39.7+/-2.8 (S.E. M.) and 44.3+/-3.1 years respectively), compared with 23 age-, sex- and body mass index-matched healthy controls. Bone mineral densities were uniformly reduced in the different regions analyzed: lumbar spine (16.1%, P<0.001), femoral neck (15.2%, P<0.001), total body (11.5%, P<0.001), and the subregions of arms (8.4%, P<0.05), legs (10.1%, P<0.05) and trunk (15.8%, P<0.001). Similar results were observed for bone mineral content, although these were less prominent. The calculated area was significantly decreased in trunk (13.8%, P<0.01) and total body (11.6%, P<0.05). Serum levels of osteocalcin were significantly decreased (28%, P<0.03) in patients with CS. No significant differences were observed for the formative markers carboxyterminal propeptide of type I procollagen and aminoterminal propeptide of type I procollagen. Markers of bone resorption, serum Crosslaps and carboxyterminal cross-linked telopeptide of type I collagen were increased in patients compared with controls, although only significantly for Crosslaps (P<0.02). No correlations between formative and resorptive markers were found in the patients, but in controls, the formative markers were positively correlated with resorptive markers. In conclusion, bone dimension and bone mineral content of the entire skeleton are found to be decreased in endogenous CS. As judged by biochemical markers of bone remodeling, this is caused by decreased bone formation and an increased bone resorption.
K Godang, T Ueland and J Bollerslev
E Qvigstad, N Voldner, K Godang, T Henriksen and J Bollerslev
To monitor β-cell function and insulin sensitivity longitudinally in a large cohort of pregnant women to elucidate mechanisms that influence glycemic control in pregnancy.
Design and methods
Five hundred and fifty-three pregnant Scandinavian women underwent 75 g oral glucose tolerance test (OGTT) at weeks 14–16 and 30–32. Insulin sensitivity (Matsuda index) and β-cell function (ratio of AUCinsulin to AUCglucose, AUCins/glc) were calculated from 520 complete tests, and subsequently β-cell function was adjusted for insulin sensitivity, rendering an oral disposition index (DIo).
Eleven women (2.1%) had gestational diabetes mellitus (GDM1) at weeks 14–16, and 49 (9.4%) at weeks 30–32 (GDM2), which is higher than that previously reported in this region. In the subdivision of OGTT, more overweight (body mass index>25) was found in glucose-intolerant groups (glucose-tolerant women (normal glucose tolerance, NGT) 38 versus GDM2 women 58 and GDM1 women 82%, P<0.005). In early pregnancy, insulin sensitivity was lowest in GDM1, intermediate in GDM2, and highest in NGT. In late pregnancy, insulin sensitivity decreased in all groups, most in gestational diabetes. β-cell function demonstrated minor shifts during pregnancy, but when adjusted for decreasing insulin sensitivity, DIo levels fell by 40% (P<0.001). DIo was significantly attenuated relative to glucose intolerance (GDM1 25% and GDM2 53%) during pregnancy. In overweight women, DIo levels were lower throughout pregnancy (P<0.001 versus normal weight women), this reduction was significant (P<0.01) in both NGT (21–25%) and GDM2 subjects (26–49%).
β-cell function adjusted for insulin sensitivity (DIo) deteriorated during pregnancy in both glucose-tolerant and glucose-intolerant women. The failure to compensate the decrease in insulin sensitivity was accentuated in overweight women.
U Schafroth, K Godang, T Ueland and J Bollerslev
There are close interactions between the adipocyte-derived hormone, leptin, and the anterior pituitary, especially the hypothalamic-pituitary-adrenal (HPA) axis. We investigated the relationship between the sympathetic adrenergic system and serum leptin levels, dependent on the function of anterior pituitary hormone axes, in 27 patients without a history of a hormone-secreting pituitary adenoma or other underlying endocrine disease. Based on responses in a routine insulin hypoglycemia test (ITT), the patients were classified as hypopituitary (HP; n=15), growth hormone deficient (GHD; n=6) or controls (CTR; 6 patients with normal responses). Nadir plasma glucose was 1.5+/-0.1 mmol/l at the time of maximum hypoglycemia. Each group had a significant increase in plasma epinephrine; however the magnitude of change was significantly higher in GHD (6.066+/-1.633 nmol/l) compared with HP patients (1.781+/-0.492 nmol/l) (P<0.01). The rise in norepinephrine was delayed (60 min) in the HP and CTR groups. However, in GHD patients there was a considerable increase at the time of hypoglycemia which was significantly different from HP (P<0.001) and CTR (P<0.05) patients. The increase in catecholamines was followed by a quick and significant decrease in serum leptin levels 45 min after an i.v. bolus injection of insulin in HP patients (-4.7+/-2.5%, P<0.05), which was significantly sustained after 60 min (-5.6+/-2.5%, P<0.05). In CTR patients there was a significant decrease in serum leptin levels 60 min after i.v. insulin (-14.4+/-6.9%, P<0.05), while no significant response was observed in the GHD group, although 5 of 6 patients had decreased levels at 45 and 60 min. No differences between the groups were found by ANOVA. In conclusion, an acute increase in endogenous circulating catecholamines is associated with a quick decrease in serum leptin levels. Intact anterior pituitary function seems not to be essential for this hitherto poorly understood mechanism.
S L Fougner, J Bollerslev, J Svartberg, M Øksnes, J Cooper and S M Carlsen
Randomised studies have demonstrated a beneficial effect of pre-surgical treatment with somatostatin analogues (SSA) in acromegaly when evaluated early postoperatively. The objective of this study was to evaluate the long-term surgical cure rates.
Newly diagnosed patients were randomised to direct surgery (n=30) or 6-month pretreatment with octreotide LAR (n=32). The patients were evaluated 1 and 5 years postoperatively. Cure was defined as normal IGF1 levels and by normal IGF1 level combined with nadir GH <2 mU/l in an oral glucose tolerance test, all without additional post-operative treatment. A meta-analysis using the other published randomised study with long-term analyses on preoperative SSA treatment was performed.
The proportion of patients receiving post-operative acromegaly treatment was equal in the two groups. When using the combined criteria for cure, 10/26 (38%) macroadenomas were cured in the pretreatment group compared with 6/25 (24%) in the direct surgery group 1 year postoperatively (P=0.27), and 9/22 (41%) vs 6/22 (27%) macroadenomas, respectively, 5 years postoperatively (P=0.34). In the meta-analysis, 16/45 (36%) macroadenomas were cured using combined criteria in the pretreatment group vs 8/45 (18%) in the direct surgery group after 6–12 months (P=0.06), and 15/41 (37%) vs 8/42 (19%), respectively, in the long-term (P=0.08).
This study does not prove a beneficial effect of SSA pre-surgical treatment, but in the meta-analysis a trend towards significance can be claimed. A potential favourable, clinically relevant response cannot be excluded.
T Ueland, S L Fougner, K Godang, T Schreiner and J Bollerslev
Objective: Acromegaly is characterized by a persistent hypersecretion of GH and provides information on long-term effects of GH on bone metabolism. The aim of this study was to examine the effect of gonadal status and disease activity on bone metabolism in active acromegaly.
Methods: Seventy-three consecutive patients with active acromegaly: 40 women and 33 men (50 ± 13 (mean ± s.d.) and 49 ± 10 years respectively) were evaluated and compared with age-, sex-, and body mass index (BMI)-matched controls by X-ray absorptiometry and biochemical analysis (markers of disease activity and bone turnover).
Results: We found that bone turnover, as evaluated by biochemical bone markers, is coupled and markedly increased in relation to disease activity in active acromegaly. Acromegalic women, but not men, were characterized by an increased bone area and slightly decreased bone mineral content resulting in significantly decreased bone mineral density (BMD) in the ultradistal radius, proximal radius, and total body. No differences in bone turnover or BMD were found between eu-and hypogonadal subjects. Multivariate analysis identified age, BMI, and gender as independent predictors of total BMD in acromegaly.
Conclusion: Our study demonstrates a decreased total body BMD in women, not men, with active acromegaly, regardless of gonadal status or disease activity. Bone turnover is markedly increased in relation to disease activity, possibly counteracting the anabolic effects of excess GH/IGF-I in these subjects. We suggest more focus on biomechanical analyses when investigating endocrine disorders affecting bone size and distribution between compartments.
T Ueland, T Dalsoren, N Voldner, K Godang, T Henriksen and J Bollerslev
Recently, experimental and clinical studies suggest that retinol-binding protein-4 (RBP4) may provide a link between obesity and insulin resistance. However, no previous studies have investigated the impact of circulating RBP4 on measures of insulin resistance in normal pregnant women, and the objective of this study is to measure serum RBP4 in early and late pregnancy and relate these to measures of insulin resistance and secretion controlling for changes in fat mass.
Design and methods
Samples were obtained during oral glucose tolerance test (OGTT) from 44 normal pregnancies at weeks 14–16 and 30–32. Measures of fat mass were body mass index (BMI) and leptin while insulin sensitivity and secretion were predicted from OGTT. Leptin and RPB4 were measured by immunoassay.
Insulin sensitivity decreased during the course of pregnancy. Insulin sensitivity and secretion were best explained by BMI and circulating leptin, but not RBP4, both in early and late pregnancy. However, a marked increase in fasting RBP4 from early to late pregnancy was observed, and this change was associated with a decline in insulin sensitivity. A marked increase in RBP4 was found during OGTT at weeks 14–16 with an opposite temporal course at weeks 30–32.
The increased fat mass and insulin resistance during normal pregnancy was best explained by measures of fat mass. However, the increase in RBP4 from early to late pregnancy, associated with a decline in insulin sensitivity, potentially indicates interactions with glucose metabolism.
J Bollerslev, T Ueland, E Grodum, E Haug, K Brixen and O Djoseland
Biochemical markers of bone remodelling were used to evaluate bone turnover in two types of autosomal dominant osteopetrosis (ADO) at baseline and during stimulation with triiodothyronine (T3). Eight patients with Type I (aged 23-61 years, mean 40.4 years) and nine patients with Type II ADO (aged 20-49 years, mean 32.8 years) were compared with 10 normal controls (aged 22-54 years, mean 35.4 years). The participants were treated with 100 microg T3 daily for 7 days and followed for a total of 16 weeks. Serum concentrations of T3 increased and corresponding suppression of TSH was observed in all participants. Both formative and resorptive bone markers were normal at baseline. After stimulation with T3, a significant increase was seen in all groups for the formative markers used. Secondary increments were observed at the end of the observation period for all groups, indicating activation of bone remodelling. A variety of resorptive markers was assessed, but no differences between patients and controls were seen. After stimulation, highly significant responses were found in all parameters in all groups, in accordance with stimulation of existing resorptive cells. However, no secondary increments were seen at the end of the observation period. A more pronounced response was found in crosslinks-related assays. The study demonstrates that it is possible to stimulate bone resorptive and formative cells with thyroid hormones in both types of ADO. Moreover, it indicates that the remodelling process is activated by a short course of T3 treatment.
C Kristo, K Godang, T Ueland, E Lien, P Aukrust, SS Froland and J Bollerslev
OBJECTIVE: It is well known that patients with endogenous Cushing's syndrome (CS) have decreased bone mass and enhanced risk for osteoporotic fractures, secondary to decreased bone formation and increased bone resorption. Immunological mediators, such as cytokines, have recently been shown to influence bone metabolism, and in the present study we examined serum levels of several cytokines, with known or potential effects on bone homeostasis, in 33 consecutive recruited untreated CS patients and 33 age-, sex- and body mass index-matched healthy controls. METHODS: Cytokine levels were measured by enzyme immunoassay and bone mass by dual-energy X-ray absorptiometry. RESULTS: Our main findings were (i) interleukin (IL)-8 and IL-18 levels were significantly increased in CS patients compared with controls. (ii) Levels of both IL-8 and IL-18 were positively correlated to serum cortisol. (iii) For serum levels of the 'classical' resorptive cytokines, i.e. IL-6 and tumor necrosis factor alpha, no significant differences were found between CS patients and controls. (iv) Raised IL-18 levels were correlated with decreased osteocalcin levels in CS patients. CONCLUSIONS: Our results demonstrated that CS patients have markedly elevated levels of the proinflammatory cytokines IL-8 and IL-18 in spite of high levels of the immunosuppressive hormone cortisol. These cytokines may be involved in the pathogenesis of disturbed bone homeostasis in CS.
T Ueland, J Bollerslev, K Godang, F Muller, SS Froland and P Aukrust
OBJECTIVE: To investigate the possible role of osteoprotegerin (OPG) in bone metabolism in humans by measuring serum levels of OPG in five well-characterized patient populations with known or suspected pathology in bone homeostasis, but with differences in the pathogenesis of these disturbances. DESIGN: The study comprised 34 patients with Cushing's syndrome (CS), 24 acromegalic patients, 16 patients with growth hormone deficiency (GHD), 29 HIV-infected patients, 25 patients with common variable immunodeficiency (CVI) and 59 age- and sex-matched healthy controls (CTR). METHODS: Serum levels of tumor necrosis factor (TNF)-alpha, OPG, C-terminal telopeptides of Type-I collagen (CTX-I) and osteocalcin were determined in all study subjects as well as cortisol (CS and CTR) and IGF-I (acromegaly, GHD and CTR). RESULTS: OPG levels were significantly elevated in both CVI (median increase approximately 32%, P < 0.05) and HIV-infected patients with especially high levels in the latter group ( approximately 52%, P < 0.001), significantly correlated with increased TNFalpha levels (r = 0.47, P < 0.02). Also CS patients had elevated serum OPG ( approximately 24%, P < 0.01), significantly correlated with increased serum cortisol (r = 0.35, P < 0.05). In contrast, OPG levels in acromegalic and GHD patients were not different from healthy controls. No relationships were found between OPG levels and CTX-I or osteocalcin. CONCLUSIONS: These findings suggest that enhanced OPG levels may be a compensatory response to enhanced osteoclast activity or negative bone remodeling balance in some conditions, but may also be a parameter of enhanced activity in the OPG system possibly correlated to enhanced activity of other members of the TNF family.
Jens Bollerslev, Thor Ueland, Anders P Jørgensen, Kristian J Fougner, Ragnhild Wergeland, Thomas Schreiner and Pia Burman
Objective: GH deficiency is associated with an increased cardiovascular mortality. Fifty-five patients with adult-onset GH deficiency (AO-GHD) (24 female, 31 male, mean age 49 years) were enrolled in a placebo-controlled double-blind crossover study to investigate the effects of GH therapy on a variety of cardiovascular risk factors representing different aspects of atherogenesis, including apolipo-proteins (Apo A-1, Apo B), markers of subclinical inflammation (high-sensitivity C-reactive protein (CRP) and interleukin-6) and markers of endothelial function (intercellular adhesion molecule-1, von Willebrand factor and sCD40L (a pro-atherogenic factor and marker for plaque destabilization)).
Methods: GH therapy was individually dosed to obtain an IGF-I concentration within the normal range for age and sex. GH and placebo were administered for 9 months each, separated by a 4 month washout period.
Results: The final mean dose of GH was 50% higher for women and IGF-I increased to the same level in both sexes. Compared with placebo, substitution with GH showed a significant effect on Apo B (mean change −0.15 (−0.22 to −0.08) mg/l) and CRP (−1.8 (−3.3 to −0.3) mg/l). The baseline level of and change in IGF-I during treatment with GH contributed significantly to the improvement in both markers. No effects were found on interleukin-6 or Apo A-1, or on markers of endothelial function. No gender differences were observed for any of the markers at baseline or following intervention.
Conclusions: GH substitution to naïve patients with AO-GHD at a low, individually titrated dose aiming at normalizing IGF-I was followed by significant reductions in Apo B and CRP, indicating a positive effect of GH on cardiovascular risk.