(A) Serum calcium concentration, adjusted for albumin concentration, revealed an increased mean serum calcium concentration in Cdc73+/- mice with parathyroid tumours when compared to Cdc73+/+ littermates with normal parathyroids (*P < 0.05). (B) Mean serum PTH concentration was elevated in Cdc73+/- mice with parathyroid tumours compared to Cdc73+/+ littermates with normal parathyroids (* P < 0.05). (C) Serum phosphate concentration in Cdc73+/- mice with parathyroid tumours compared to Cdc73+/+ littermates with normal parathyroids. Cdc73+/- mice with parathyroid tumours are shown as filled symbols and Cdc73+/+ littermates with normal parathyroids are shown as open symbols. Squares represent males and circles represent females. The age range of the mice was 17-24 months (mean ±SEM = 20.0 ±0.30). Combined results from males and females for serum calcium, phosphate and PTH concentrations are shown, as there were no significant gender differences. Horizontal lines indicate mean values together with the standard error of the mean (SEM), which is shown numerically below each group and the number (N) of mice.