hi this is tom from zero finals calm in this video I'm going to go through hyperparathyroidism by definition hyperparathyroidism is a high level of parathyroid hormone and there's three types primary secondary and tertiary and it's these three types that causes a lot of confusion amongst medical students and doctors and it's the reason that I wanted to make this video just to clarify what the different causes are firstly I'm going to go through some simplified physiology bear in mind that in reality the process are a bit more complicated but for the purpose of medical school everyday practice and understanding hyperparathyroidism this is all you really need to know there are four parathyroid glands situated in four corners of the thyroid gland the parathyroid glands specifically the chief cells in the glands produce parathyroid hormone in response to low blood calcium concentration parathyroid hormone acts to raise blood calcium level by increasing the absorption of calcium from the intestines increasing the reabsorption of calcium in the kidneys basically reducing how much is secreted in the urine and increasing the osteoclast activity in the bones now remember that the osteoclasts are responsible for breaking down the bones and releasing calcium into the blood the other player in the game is vitamin D and vitamin D is a hormone that the body creates in response to sunlight but it can also be obtained through food or supplementation to simplify what vitamin D does it acts on all of the processes that we talked about to increase absorption of calcium from the intestines kidneys and bones parathyroid hormone also acts on vitamin D to convert it into some of its active forms so vitamin D acts basically alongside parathyroid hormone to raise the blood calcium level a deficiency in vitamin d as a result could lead to a low calcium level so let's talk about hyperparathyroidism the easiest cause of this to explain is primary hyperparathyroidism and this is just caused by uncontrolled parathyroid hormone being produced by a tumor of the parathyroid glands this causes increased absorption of calcium and leads to hypercalcemia which is an abnormally high level of calcium in the blood and this can be treated using surgical removal of the tumor the next cause of an abnormally high power or doorman is called secondary hyperparathyroidism and this is where either insufficient vitamin D or chronic renal failure leads to reduced absorption of calcium from the intestines kidneys and bones this vitamin D or chronic renal failure leads to hypocalcemia or a low level of calcium in the blood and the parathyroid glands react to this low level of calcium by excreting more parathyroid hormone to try and compensate over time the total number of cells and the parathyroid gland increases as they respond to the increased need to produce parathyroid hormone this is called hyperplasia and it leads to the glands becoming more bulky and secreting more parathyroid hormone as a baseline level the serum calcium level will normally be low or normal but the parathyroid hormone will be high in secondary hyperparathyroidism and this condition can be treated by correcting the underlying cause like the vitamin D deficiency or doing a renal transplant in patients with renal failure the final cause of high parathyroid hormone is called tertiary hyperparathyroidism and this happens when secondary hyperparathyroidism continues for a long period of time and it leads to a big hyperplasia of the glands and the baseline amount of parathyroid hormone that's being excreted by those glands increases dramatically and so what happens is when you treat the secondary hyperparathyroidism and you remove the need for so much parathyroid hormone the level remains high because those glands are so used to producing so much parathyroid hormone what happens is this leads to a high absorption of calcium in the intestines kidneys and bones and it causes hypercalcemia or a high level of calcium in the blood and we can treat this by surgically removing those big bulky glands and leaving just enough tissue that you get a normal level of parathyroid hormone so to summarize the types causes the effects on parathyroid and calcium and the treatment primary hyperparathyroidism is caused by a tumor of the parathyroid glands it causes a high parathyroid hormone that leads to a high serum calcium and the treatment is surgery secondary hyperparathyroidism is caused by a deficiency in vitamin D or chronic kidney disease the parathyroid hormone level will be high but the serum calcium level will be low or normal and the treatment is to improve the vitamin D deficiency or to do a renal transplant in chronic kidney disease and tertiary hyperparathyroidism is a result of hyperplasia of the parathyroid glands after secondary hyperparathyroidism and it leads to a high parathyroid gland and as long as the cause of the secondary hyperparathyroidism is treated it leads to a high serum calcium level and the treatment of this would be surgery to remove the extra hyper blaz'd parathyroid tissue so thanks for watching I hope you found this video helpful if you did don't forget there's plenty of other resources on the zero to finals website including loads and loads of notes on various different topics that you might cover in medical school with specially made illustrations there's also a whole test section where you can find loads of questions to test your knowledge and see where you're up to in preparation for your exams there's also a blog where I share a lot of my ideas about a career in medicine and tips on how to have success as a doctor and if you want to help me out on YouTube you can always leave me a thumbs up give me a comment or even subscribe to the channel so that you can find out when the next videos are coming out so I'll see you again soon