Hypothesis and objectives: Cardiovascular surgery with extracorporeal circulation (ECC) is highly stressful, inducing marked changes in calcium and magnesium homeostasis. Nevertheless, no studies have assessed osteoblastic/osteoclastic activity during and after heart surgery with ECC. Our objective was to analyze changes in serum levels of parameters reflecting phosphorus and calcium metabolism and markers of bone remodelling in this context.
Patients and methods: Changes in serum levels of calcium, phosphorus, whole parathyroid hormone (PTH), magnesium, cortisol, interleukin-6, total alkaline phosphatase, osseous alkaline phosphatase (OAP), osteocalcin, propeptide of type 1 procollagen (PCP1), and carboxyl-terminal telopeptide of type 1 collagen (CTT1) during the 24 perioperative hours in 16 patients undergoing cardiac surgery with ECC.
Results: Total calcium decreased during ECC, triggering acute release of PTH. Osteocalcin decreased at 24 hours in a way that was not accounted for by hemodilution. OAP changes, on the other hand, were consistent with albumin levels and blood cell counts. PCP1 and CTT1 did not change, although correcting for dilution shows that these factors can in fact be considered to have increased.
Conclusions: The parathyroid gland is activated during ECC. Markers of bone metabolism behave differently over time in response to heart surgery. The data suggest that heart surgery induces discordant responses in various bone cell functions.