title: Hypoparathyroidism and pseudohypoparathyroidism.
abstract: The principal function of the parathyroid hormone (PTH) is maintenance of calcium plasmatic levels, withdrawing the calcium from bone tissue, reabsorbing it from the glomerular filtrate, and indirectly increasing its intestinal absorption by stimulating active vitamin D (calcitriol) production. Additionally, the PTH prompts an increase in urinary excretion of phosphorus and bicarbonate, seeking a larger quantity of free calcium available in circulation. Two mechanisms may alter its function, limiting its control on calcium: insufficient PTH production by the parathyroids (hypoparathyroidism), or a resistance against its action in target tissues (pseudohypoparathyroidism). In both cases, there are significantly reduced levels of plasmatic calcium associated with hyperphosphatemia. Clinical cases are characterized by nervous hyperexcitability, with paresthesia, cramps, tetany, hyperreflexia, convulsions, and tetanic crisis. Abnormalities such as cataracts and basal ganglia calcification are also typical of these diseases. Treatment consists of oral calcium supplementation associated with increased doses of vitamin D derivatives.
authors.affiliation: Division of Endocrinology, EPM, UNIFESP, São Paulo, SP, Brazil.
authors.forename: Sergio S
authors.initials: SS
authors.lastname: Maeda
authors.forename: Erika M
authors.initials: EM
authors.lastname: Fortes
authors.forename: Ulisses M
authors.initials: UM
authors.lastname: Oliveira
authors.forename: Victoria C Z
authors.initials: VC
authors.lastname: Borba
authors.forename: Marise
authors.initials: M
authors.lastname: Lazaretti-Castro
mesh_terms: D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood*; D002136:Calcium, Dietary / Q000008:administration & dosage; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000175:diagnosis; D007011:Hypoparathyroidism / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D010281:Parathyroid Hormone / Q000097:blood / Q000502:physiology*; D010758:Phosphorus / Q000097:blood; D011547:Pseudohypoparathyroidism / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D014807:Vitamin D / Q000097:blood / Q000627:therapeutic use
chemical_list: D002136:Calcium, Dietary; C470125:PTH protein, human; D010281:Parathyroid Hormone; D014807:Vitamin D; D010758:Phosphorus; D002117:Calcitriol; D002118:Calcium