ECE2014 Poster Presentations Calcium and Vitamin D metabolism (68 abstracts)
Introduction: Heterozygous inactivating mutations of the calcium sensing receptor (CaSR) gene cause mild alterations in calcium metabolism (familiar hypocalciuric hypercalcemia (FHH)). However, in addition to the parathyroid gland CaSR expression was recently identified in the myocardium and many other endocrine cells including pancreatic islet cells, entero-endocine cells and adipose tissue. So far, it is unknown whether FHH is associated with cardio-metabolic alterations that might be of clinical significance.
Methods: In eight FHH patients and nine controls matched for major anthropometric characteristics (45±6 years; BMI 29.5±2 kg/m2), ectopic lipid deposition and heart function were investigated using magnetic resonance spectroscopy and imaging. Oral glucose tolerance test derived indices for insulin-sensitivity and -secretion, and endocrine responses to systemic calcium stimulation were studied.
Results: Insulin sensitivity (CLIX 4.5±0.6 vs 4.3±0.4 mg/kg per min; OGIS 399±31 vs 419±17 ml/(min×m2), basal (insulin secretion rate 266±33 vs 218±25 pmol/min) and glucose stimulated β-cell function (IGI: 140±48 vs 118±21 pmol/mmol and adaptation index 180.2±12.2 vs 176.2±17.4) as well as calcium stimulated insulin secretion were comparable between FHH and controls respectively. Also ectopic lipid accumulation in the liver (13.7±15.4 vs 8.3±9.1%) and the myocardium (0.39±0.3 vs 0.32±0.1%) as well as systolic (ejection fraction 71.5±8 vs 72.8±8% and cardiac index 2.35±0.4 vs 2.35±0.5 ml/min per m2) and diastolic (E:A ratio 1.4±0.6 vs 1.3±0.7) myocardial function were not different between the groups.
Conclusion: Despite comprehensive cardio-metabolic phenotyping no clinically relevant alterations in myocardial function, lipid distribution, or glucose metabolism were observed. Thus, patients can be reassured that FHH reflects a laboratory finding with no need for intense medical surveillance.