Endocrine Abstracts

In recent years, there has been increasing evidence for the hypothesis of bones as endocrine organs. Osteocalcin, long considered just a marker of new bone formation, is now seen as the first hormone produced by bones, and seems to be associated with regulating glucose metabolism and reproduction. The aim of this work was to monitor changes of osteocalcin in reaction to hypoglycaemia, and determine if there are differences in such reactions between the sexes. The study included 61 healthy probands with physiological calciophosphate metabolism (30 men and 31 women). We applied to each of them an insulin tolerance test, and then monitored levels of undercarboxylated osteocalcin and reactions to hypoglycaemia at regular time intervals. We found differences in the reaction to hypoglycaemia between the sexes. In men there was a significant decline in undercarboxylated osteocalcin between the 30 and 40 min (P<0.0015), which reflects a reaction to a glycemic decline between 25 and 30 min, followed by reversal. Low undercarboxylated osteocalcin in men lasted up to 90 min, after which they returned to levels before the test. In women we did not find any significant changes in undercarboxylated osteocalcin levels. Changes in undercarboxylated osteocalcin induced by hypoglycaemia indicate a relationship between bones and glucose metabolism. There was an interesting difference between the sexes. However, a definitive conclusion about the role of osteocalcin in human metabolism will require numerous future studies. Acknowledgements: This study was supported by the Ministry of Health of the Czech Republic (MZ ČR – RVO; Endokrinologický ústav – EÚ, 00023761).