Calcitriol is the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. Calcitriol increases blood calcium (Ca2+) mainly by increasing the uptake of calcium from the intestines.It can be given as a medication for the treatment of low blood calcium and hyperparathyroidism due to kidney disease, low blood calcium due to hypoparathyroidism, osteoporosis, osteomalacia, and familial hypophosphatemia, and can be taken by mouth or by injection into a vein. Excessive amounts or intake can result in weakness, headache, nausea, constipation, urinary tract infections, and abdominal pain. Serious side effects may include high blood calcium and anaphylaxis. Regular blood tests are recommended after the medication is started and when the dose is changed.Calcitriol was identified as the active form of vitamin D in 1971 and the drug was approved for medical use in the United States in 1978. It is available as a generic medication. In 2017, it was the 256th most commonly prescribed medication in the United States, with more than one million prescriptions.It is on the World Health Organizations List of Essential Medicines. Medical use
Calcitriol is prescribed for:
Treatment of hypocalcaemia – hypoparathyroidism, osteomalacia (adults), rickets (infants, children), renal osteodystrophy, chronic kidney disease
Treatment of osteoporosis
Prevention of corticosteroid-induced osteoporosisCalcitriol has been used in an ointment for the treatment of psoriasis, although the vitamin D analogue calcipotriol (calcipotriene) is more commonly used.
Upon the start of using antidepressants, many clinicians will note that sometimes the sudden onset of suicidal ideation may accompany treatment. This has caused the Food and Drug Administration (FDA) to issue a warning stating that sometimes the use of antidepressants may actually increase suicidal ideation. Medical studies have found antidepressants help treat cases of suicidal ideation and work especially well with psychological therapy. Lithium reduces the risk of suicide in people with mood disorders. Tentative evidence finds clozapine in people with schizophrenia reduces the risk of suicide. See also
Existential angst
Existential crisis
Existential nihilism
Finno-Ugrian suicide hypothesis
Mental health first aid
Suicide attempt
Suicide crisis

References
Further reading
Beck, AT; Steer, RA; Kovacs, M; Garrison, B (1985). "Hopelessness and eventual suicide: a 10-year prospective study of patients hospitalized with suicidal ideation". Am J Psychiatry. 142 (5): 559–563. CiteSeerX 10.1.1.462.6328. doi:10.1176/ajp.142.5.559. PMID 3985195. Uncapher, H (2000–2001). "Cognitive biases and suicidal ideation in elderly psychiatric inpatients". Omega. 42 (1): 21–36. doi:10.2190/6uu8-hk8e-hl0v-q4cu. S2CID 144242247. Uncapher, H; Gallagher-Thompson, D; Osgood, NJ (1998). "Hopelessness and suicidal ideation in older adults". The Gerontologist. 38 (1): 62–70. doi:10.1093/geront/38.1.62. PMID 9499654. External links

Evaluation and Treatment of Patients with Suicidal Ideation Archived 2006-09-25 at the Wayback Machine
Suicidal Thought Archived 2014-07-02 at the Wayback Machine
National Suicide Prevention Lifeline: Warning signs Archived 2016-04-08 at the Wayback Machine