PTH and hyperparathyroidism: In MEN2, PHPT was the first manifestation less frequently compared to hyperparathyroidism-jaw tumor syndrome (0% versus 85%, p = 0.001), while serum PTH (median: 108.0 versus 383.5 pg/mL, p = 0.01) and serum total calcium (mean ± SD: 10.6 ± 1.1 versus 12.9 ± 1.8 mg/dL, p < 0.001) levels were lower, and nephrolithiasis occurred less often (18.2% versus 65%, p = 0.02).