A primary problem in the parathyroid glands, producing too much parathyroid hormone causes raised calcium levels in the blood ( hypercalcaemia ) and this is referred to as primary hyperparathyroidism . There is a similar but much rarer condition called tertiary hyperparathyroidism that causes hypercalcaemia due to excess parathyroid hormone production on the back drop of all four glands being overactive. Secondary hyperparathyroidism occurs in response to low blood calcium levels and is caused by other mechanisms, for example, kidney disease and vitamin D deficiency.
Confusion also exists between the words progesterone and progestogen or progestin. The former is a natural hormone made by the body, of which there is only one. The latter is synthetic and there are many varieties on the market, each having a molecular structure that differs from that of progesterone. It was discovered that progesterone, when taken orally, is mostly destroyed by the gut and liver. This was an opportunity for the drug companies to make a synthetic which wasn't destroyed. This is now used in Contraceptives and HRT (hormone replacement therapy) .