title: Causes and differential diagnosis of hypocalcemia--recommendation proposed by expert panel supported by ministry of health, labour and welfare, Japan.
abstract: Serum calcium (Ca) level is maintained within a narrow range mainly by actions of parathyroid hormone (PTH) and 1,25-dihydroxyvitmain D [1,25(OH)(2)D]. While it is not rare to encounter hypocalcemia in clinical practice, there is currently no practical guideline for the differential diagnosis of hypocalcemia. We therefore propose flowcharts for the differential diagnosis of hypocalcemia and hypoparathyroidism, especially PTH-deficient hypoparathyroidism in which many genetic or other causes have been identified recently. Hypocalcemia can be divided into two categories, hypocalcemia with low serum phosphate level, and one with normal to elevated serum phosphate level. Deficient actions of 1,25(OH)(2)D, loss of Ca into urine, and deposition of Ca in bone or soft tissues are main causes of hypocalcemia with low to low normal serum phosphate level. Hypocalcemia with high normal to high serum phosphate level includes chronic renal failure and hypoparathyroidism. Hypoparathyroidism is subdivided into PTH-deficient hypoparathyroidism and pseudohypoparathyroidism. Recent investigations identified several causes of PTH-deficient hypoparathyroidism, including genetic abnormalities and parathyroid autoantibodies, which should be differentiated from idiopathic hypoparathyroidism. Physical and laboratory findings, the time of the onset of diseases and accompanying illness can be clues for identifying causes of PTH-deficient hypoparathyroidism.
authors.affiliation: Division of Nephrology & Endocrinology, Department of Medicine, University of Tokyo Hospital, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukumoto
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Namba
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ozono
authors.forename: Mika
authors.initials: M
authors.lastname: Yamauchi
authors.forename: Toshitsugu
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Toshimi
authors.initials: T
authors.lastname: Michigami
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Daisuke
authors.initials: D
authors.lastname: Inoue
authors.forename: Masanori
authors.initials: M
authors.lastname: Minagawa
authors.forename: Itsuro
authors.initials: I
authors.lastname: Endo
authors.forename: Toshio
authors.initials: T
authors.lastname: Matsumoto
mesh_terms: D003937:Diagnosis, Differential; D006801:Humans; D006996:Hypocalcemia / Q000145:classification / Q000175:diagnosis* / Q000209:etiology*; D007011:Hypoparathyroidism / Q000175:diagnosis / Q000209:etiology / Q000235:genetics; D007564:Japan; D008274:Magnesium / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood / Q000172:deficiency; D010710:Phosphates / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; D008274:Magnesium