EFFECTS OF SERUM CALCIUM, PHOSPHORUS AND PARATHYROID HORMONE CONCENTRATIONS ON GLUCOSE METABOLISM IN PATIENTS WITH ASYMPTOMATIC PRIMARY HYPERPARATHYROIDISM

Context. The metabolic effects of primary hyperparathyroidism (PHPT) causing increased cardiovascular morbidity have begun to gain importance in medical science, and the number of studies investigating glucose metabolism disorders in asymptomatic PHPT patients is rare. Objective. To evaluate the relationship between glucose metabolism disorders and calcium, phosphorus and parathyroid hormone concentrations in asymptomatic PHPT patients. Subjects and Methods. Fifty-five asymptomatic PHPT patients were included into the study. Control group consisted of 55 normocalcemic cases. Oral glucose tolerance test (OGTT) of 75 g was performed with patients and controls. Insulin resistance was calculated by HOMA index. Results. No significant difference was present between groups regarding fasting plasma glucose, basal insulin and HOMA levels. Glucose levels measured at minutes 30, 90 and 120 after. OGTT were higher in patients than in controls (p=0.041, p=0.025 and p=0.001, respectively). No individuals in both groups were diagnosed with diabetes mellitus. While impaired glucose tolerance was detected in six patients with asymptomatic PHPT, no impaired glucose tolerance was determined in controls. A positive correlation was found between serum calcium levels, and fasting plasma glucose and OGTT glucose levels were measured at minutes 60, 90 and 120. Mean fasting plasma glucose was significantly higher in patients with serum calcium levels >= 10.5 mg/dL than those with serum calcium levels <10.5 mg/dL (p=0.008). No significant correlation was detected between serum phosphorus and parathyroid hormone levels, and glucose levels were determined in OGTT and HOMA index. Conclusion. Increased levels of serum calcium affect glucose metabolism, so leading to glucose intolerance.