PTH and hydrops fetalis: In a large study (n = 49,825, 3009 with HF) with a HF group (mean age of 76 ± 11 years) and control group (mean age of 64 ± 12 years), the patients with HF had a lower median 25(OH)D level compared to the control group (36.9 nmol/L vs. 40.7 nmol/L; p < 0.00001)) [6], whereas PTH was significantly higher in the HF group vs. the control group (198 (84–226) vs. 77 (52–118) pg/mL, p < 0.00001), but mortality data were not mentioned.