Severe Hypocalcemia During JAK1/2 Inhibitor Therapy for Myelofibrosis in a Patient with Liver Cirrhosis

Intern Med. 2025 Aug 1;64(15):2338-2343. doi: 10.2169/internalmedicine.4723-24. Epub 2025 Jan 15.

Abstract

We herein report a 56-year-old man with severe hypocalcemia during ruxolitinib therapy for myelofibrosis transitioning from Janus kinase 2 mutation-positive polycythemia vera. Blood transfusions were administered every one to two weeks for ruxolitinib-induced anemia. Blood tests revealed hypocalcemia with low tartrate-resistant acid phosphatase-5b, 25-hydroxyvitamin D (25 (OH) D), and 1,25-dihydroxyvitamin D3 (1,25 (OH) 2 D3) levels within the lower reference range. Intact-parathyroid hormone levels were relatively low compared to calcium levels. Severe hypocalcemia with ruxolitinib is rare and may be caused by a combination of factors, impaired vitamin D activation due to liver or renal insufficiency, accumulation of calcium-chelating agents from blood transfusions, and inadequate compensatory response to PTH.

Keywords: hypocalcemia; liver cirrhosis; myelofibrosis; polycythaemia vera; ruxolitinib.

Publication types

  • Case Reports

MeSH terms

  • Humans
  • Hypocalcemia* / chemically induced
  • Hypocalcemia* / diagnosis
  • Janus Kinase 1* / antagonists & inhibitors
  • Janus Kinase 2* / antagonists & inhibitors
  • Liver Cirrhosis* / complications
  • Liver Cirrhosis* / drug therapy
  • Male
  • Middle Aged
  • Nitriles
  • Primary Myelofibrosis* / complications
  • Primary Myelofibrosis* / drug therapy
  • Pyrazoles* / adverse effects
  • Pyrazoles* / therapeutic use
  • Pyrimidines
  • Severity of Illness Index

Substances

  • Nitriles
  • ruxolitinib
  • Pyrazoles
  • Pyrimidines
  • Janus Kinase 2
  • Janus Kinase 1
  • JAK2 protein, human
  • JAK1 protein, human