Mild primary hyperparathyroidism as defined in the Italian Society of Endocrinology's Consensus Statement: prevalence and clinical features

Background Mild primary hyperparathyroidism (PHPT) was recently clearly defined for the first time. Our study was thus aimed to pinpoint proportion and clinical characteristics of this kind of patients. Design and patients We retrospectively evaluated our series of 360 consecutive patients with PHPT, selecting those with all features allowing a correct classification (serum total and ionized calcium, phosphate, creatinine, PTH, 25OHD, urinary calcium, renal and neck ultrasound, MIBI scintiscan, and DEXA at lumbar spine, femoral neck, and distal third of radius). Patients were defined asymptomatic (aPHPT) when bone or kidney was not involved and no hypercalcemic symptom occurred; mild PHPT was defined as aPHPT not meeting updated surgical criteria. Results Seventy-five patients among 172 classified as aPHPT had all available data required for surgical evaluation and could be evaluated. Sixty/75 met surgical criteria and the remaining 15 were classified as mild. Mild PHPT patients had lower total and ionized calcium, urinary calcium, and PTH levels than aPHPT meeting surgical criteria, while vitamin D levels and BMD were similar. Conclusions Mild PHPT strictly defined according to the last consensus represents a small subgroup with a less active form of the disease.