PTH and hydrops fetalis: Although 25(OH) D concentrations were similarly low in both groups, secondary hyperparathyroidism (PTH > 6.8 pmol/L) was present in 30.2% of patients with cervical and in 41.3% with trochanteric HF (p = 0.033), and the mean PTH value was significantly higher in the latter group (p = 0.001).