The Calcium Loading Test in Primary Hyperparathyroidism – Does it Provide Useful Information?

Abstract Objective: to describe the results from intravenous calcium loads in patients with suspected PHPT. Methods: This was a retrospective cross-sectional study inpatients’ data review. Baseline serum calcium, phosphates, magnesium, creatinine, alkaline phosphatase, beta-crosslinks were recorded. The loading had been performed after an overnight fasting. Calcium gluconate 0.25 mmol/kg body weight (10 mg/kg) dissolved 0.9% Sodium Chloride infused intravenously for 3 hours. Blood samples total phosphates and iPTH drawn before up 60 minutes load. intact parathyroid hormone (iPTH) 25(OH)-vitamin D determined by electro-hemi-luminescence (Elecsys, Roche Diagnostics). PTH inhibition rate % (PTH-IR), increment, ratio R (ΔPTH/ΔCalcium) product P (calcium X at test end) calculated. Results: 23 PHPT complete tests. suppression < 30% 17.4% of participants, 50% – 21.7% > remaining 60.9%. One patient displayed 75%. Ratio 4.0 all but one patient. Product above 1100 mg/dl x pg/ml 9 participants (39.1%). Sixteen (69.6%) positive localization US or SPECT-CT. level not related any parameter except volume lesion. Conclusion: unable differentiate forms It did add great value diagnostic work-up