PTH and selenium deficiency: Selenium deficiency in the diet of rats increased bone resorption, not only due to the decrease in the activity of selenium-dependent enzymes, but also to a decrease in calcium concentration, disturbed growth hormone secretion in the pituitary gland, reduced insulin-like growth factor in the plasma, increased concentrations of parathyroid hormone and 1,25-dihydroxyvitamin D, and excessive excretion of calcium in the urine [16,39].