The results of those studies were vitamin D 25-hydroxy of <4 nanograms (ng)/mL) (range 20–80 ng/mL), vitamin D 1,25-hydroxy of 10.5 ng/mL (range 19.9–79.3 ng/mL), and parathyroid hormone (PTH) of 636 picograms (pg)/mL) (range 8–54 pg/mL), proving that the etiology of the rickets was secondary to a vitamin D nutritional deficiency. Here, PTH is linked to rickets.