In the first criteria set, patients must have ≥10% bone marrow clonal plasma cells plus ≥1 of the CRAB criteria; in the second criteria set, patients must have ≥10 bone marrow clonal plasma cells plus ≥1 of the following findings, ≥60% bone marrow clonal plasma cells, a free κ/λ or λ/κ light chain ratio in serum of ≥100 (the involved clonal light chain concentration must be ≥100 milligrams/liter), and/or >1 focal bone lesion on magnetic resonance imaging. The 5 year medium survival of patients with multiple myeloma treated with currently used treatment regiments is 48.5%. Light chain multiple myeloma
Light chain multiple myeloma is diagnosed in patients who have: a) the criteria for diagnosis of multiple myeloma except having a serum free light chain ratio outside the normal range of 0.26 to 1.65 without evidence of an intact immunoglobulin or free heavy chain; or b) an extreme free light chain ratio, i.e. outside the range of 0.02 to 100 (with the light chain having the lower concentration being present at >10 milligrams/liter) regardless of the stage of their plasma cell dyscrasia. At the time of diagnosis, 30% to 50% of light chain multiple myeloma patients have severe renal dysfunction or kidney failure due to light chain myeloma cast nephropathy or the nephrotoxic effects of free light chains on renal tubular cells.
Activity is also decreased by high levels of serum phosphate and by an increase in the production of the hormone FGF23 by osteocyte cells in bone.Calcitriol is also produced outside the kidney in small amounts by many other tissues including placenta and activated macrophages.When the drug alfacalcidol is used, 25-hydroxylation in the liver produces calcitriol as the active metabolite. This will produce greater effects than other vitamin D precursors in patients with kidney disease who have loss of the renal 1-alpha-hydroxylase. Interactive pathway map
Metabolism
The halflife of calcitriol in the body is measured in hours, unlike its precursor calcifediol, whose halflife is measured in weeks. Calcitriol is inactivated by further hydroxylation to form 1,24,25-trihydroxyvitamin D, calcitroic acid. This occurs through the action of the CYP24A1 24-hydroxylase. Calcitroic acid is more soluble in water and is excreted in bile and urine. History
It was first identified in 1971 by Michael F. Holick working in the laboratory of Hector DeLuca, and also by Tony Norman and colleagues. Names
Calcitriol refers specifically to 1,25-dihydroxycholecalciferol. Because cholecalciferol already has one hydroxyl group, only two (1,25) are further specified in this nomenclature, but in fact there are three (1,3,25-triol), as indicated by the name calcitriol. The 1-hydroxy group is in the alpha position, and this may be specified in the name, for instance in the abbreviation 1α,25-(OH)2D3.Calcitriol is, strictly, the 1-hydroxylation product of calcifediol (25-OH vitamin D3), derived from cholecalciferol (vitamin D3), rather than the product of hydroxylations of ergocalciferol (vitamin D2). 1α,25-Dihydroxyergocalciferol (ercalcitriol) should be used for the vitamin D2 product.