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Hyponatraemia due to hypothyroidism: a rare side effect from pomalidomide
  1. Anum Qureshi1 and
  2. Ji Hyun Rhee1,2
  1. 1Internal Medicine, Greater Baltimore Medical Center, Towson, Maryland, USA
  2. 2Pulmonary and Critical Care Medicine, Greater Baltimore Medical Center, Towson, Maryland, USA
  1. Correspondence to Dr Ji Hyun Rhee; jrhee{at}gbmc.org

Abstract

Pomalidomide is an immunomodulatory drug used for relapsed and refractory multiple myeloma (RRMM). Hypothyroidism is an uncommon side effect of pomalidomide. We present a 70-year-old male patient with RRMM on daratumumab, pomalidomide and dexamethasone, who presented with 2 weeks of fatigue. Laboratory values showed sodium of 120 mEq/L, plasma osmolarity of 256 mOsm/kg, urine osmolarity of 648 mOsm/kg and urine sodium of 93 mEq/L. Adrenocorticotropic hormone (ACTH) stimulation test was within normal limits. Thyroid-stimulating hormone (TSH) was 88.6 IU/mL (0.380–4.700 IU/mL), total triiodothyronine (TT3) <21 ng/mL (0.8–2 ng/mL), free thyroxine (fT4) 0.10 ng/dL (0.93–1.70 ng/dL) and free triiodothyronine (fT3) <0.5 pg/mL (2.3–4.2 pg/mL). Antithyroid peroxidase antibody was 726 IU/mL (<9 IU/mL). TSH 1 year ago was 2.88 IU/mL and TT3 was 1.06 ng/mL. He was started on levothyroxine with improvement in his symptoms, sodium level and thyroid functions. The most likely culprit was pomalidomide. Checking thyroid functions before and periodically while on pomalidomide is important in screening for this possible side effect.

  • endocrine system
  • haematology (drugs and medicines)
  • thyroid disease
  • unwanted effects / adverse reactions
  • fluid electrolyte and acid-base disturbances

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Footnotes

  • Contributors Dr AQ wrote the initial case report description as well as discussion on the manuscript, and edited per corresponding author’s comments. Also did literature search and did the initial revision after the reviewer’s comments. Dr JHR reviewed, edited and revised the manuscript, corrected grammar, answered reviewer's comments, with final approval for submission and agreed to answer any questions regarding the case report. After revision per reviewer’s comments by Dr AQ, re-revised the manuscript and finalised the last version.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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