Endocrine Abstracts

Background: Soluble alpha klotho (sαKL) is a circulating protein that has been linked to the growth hormone (GH) axis. We previously showed its association to disease activity in patients with acromegaly, with considerable robustness towards biological confounders. However, there is scarce data in literature regarding the analytical performance of the assay, and pre-analytical stability of sαKL in blood samples. Objective: We aimed to evaluate ...

We previously have shown in a cohort of 236 non-fasted women that before and after a short high intensity exercise protocol (HIP) till exhaustion serum concentrations of 20 and 22 kD growth hormone (hGH) are highly correlated (P<0.0001). Although the GH response to exercise exhibited huge inter-individual differences, the 20 kD/22 kD-GH-ratio remained unchanged (9.6% vs 11.1%, P=0.313). A subgroup of the women was also studied under fasted conditions in a...

Background: We recently have shown a close association of high concentrations of soluble alpha klotho (sαKL) to disease activity in acromegaly. Small pilot studies suggested that sαKL concentrations might be reduced in GH deficiency (GHD) and increase after recombinant human GH (rhGH) therapy. Our aim was to evaluate the potential of sαKL as a biomarker in GHD.Methods: We evaluated sαKL in comparison to the classical biomarkers GH, IG...

GH suppression during OGTT is the gold-standard test in diagnosis and monitoring of acromegaly. However, discrepancies between GH nadir and IGF-I have been described and have triggered search for factors modifying the extent of GH suppression. Cut-offs at 1.0 or 0.4 ng/ml are currently recommended with modern, highly sensitive GH assays. To establish assay specific GH nadir cutoffs for the 22kD GH specific IDS-iSYS assay, we examined 381 subjects (319 females, 62 males) with n...

Background: Recent studies reported high soluble α-klotho concentrations (α-klotho) in active acromegaly, with normalization after successful therapy. We showed that α-klotho correlates to GH and even better to IGF-I. So far, most studies employed an immunoassay from Immuno-Biological Laboratories (IBL) for measurement of α-klotho, but other assays are available. Agreement between assays remains questionable since α-klotho exists in several isoforms: K...

Background: Soluble alpha klotho (sαKL) is high in active acromegaly, normalizes after disease control, and therefore is suggested as a new biomarker for growth hormone (GH) excess. However, little is known about the impact of biological variables other than GH.Methods: Serum sαKL (pg/ml) was measured by ELISA (IBL, Hamburg, Germany). We first evaluated pre-analytical stability, defined a reference interval for sαKL in healthy subjects (A:...

Background: Alpha klotho is a transmembrane protein that regulates calcium metabolism. Its soluble portion has been linked to endocrine functions. We have recently shown high concentrations of serum soluble alpha klotho (sαKL) in active acromegaly. There is limited information about regulation of sαKL secretion. We aimed to gain insight about sαKL as a potential biomarker for H-related diseases.Methods: SαKL was measured by ELISA (IBL...

GH consists of various molecular isoforms. Most abundant is 22 kDa-GH (80–90% of total GH), followed by 20 kDa-GH (5–15% of total GH). The biological significance of 20 kDa-GH remains unclear, but its effects appear comparable to those of 22 kDa-GH. Acromegaly is characterized by chronic GH excess. Data on GH isoforms in acromegaly are scarce, but an increased 20 kDa-/22 kDa-GH-ratio (20k-ratio) has been described. Our aims were to compare the 20k-ratio in a larger c...