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General Rehabilitation

(Kiosk 1) Hyperkalemia: A Rare, but Serious Side Effect of Low Molecular Weight Heparin: A Case Report

Saturday, November 18, 2023
8:00 AM – 9:15 AM CT

    Primary Author(s)

  • Anne E. Serrao, DO

    Resident
    ECU Health (Vidant Medical Center/East Carolina University) PM&R Program
    Greenville, North Carolina

    • Co-Author(s)

  • RM

    Raymund V. Millan, MD

    Director SCI Rehabilitation Service
    Vidant Medical Center/East Carolina University PM&R Program
    Greenville, North Carolina

Case Diagnosis: 49-year-old male with hyperkalemia secondary to low-molecular weight heparin mediated hypoaldosteronism

Case Description or Program Description: Patient was admitted for surgery of a thoracic arachnoid cyst. Hospital course was complicated by a spinal cord infarct post procedure, resulting in a new complete spinal cord injury. Admission labs to Inpatient Rehabilitation (IPR) showed severe hyperkalemia.

Setting: Academic IPR and Acute Care Hospital

Assessment/Results: Admission labs showed severe hyperkalemia of 7.0. Electrocardiogram was obtained and did not show significant abnormalities. Patient was returned to the acute hospital for closer cardiac monitoring, where he was started on potassium lowering agents. His hyperkalemia was found to be secondary to LMWH mediated hypoaldosteronism, which was confirmed by a low trans tubular gradient of potassium. His potassium returned to a safe level, allowing transfer back to IPR.

Discussion (relevance): LMWH mediated hypoaldosteronism is an uncommon side effect of LMWH. Its prolonged use can cause a reduction in the width of the zona glomerulosa of the adrenal gland, the site of aldosterone synthesis, causing hyperkalemia. Patients at highest risk are the elderly, diabetics, and those with renal insufficiency. The suppression of aldosterone typically occurs within a week of LMWH initiation—typically within the timeline when patients are transferred from the acute hospital to IPR. Treatment includes stopping LMWH, starting potassium reducing medication, and cardiac monitoring. It is crucial that patients newly started on LMWH, particularly in higher risk groups, have their potassium levels routinely monitored to prevent serious side effects of hyperkalemia, such as cardiac arrest.

Conclusions: LMWH mediated hypoaldosteronism is an uncommon, but serious, side effect of LMWH. Treatment includes stopping LMWH, starting potassium reducing medication, and cardiac monitoring. For patients recently started on LMWH, especially those in higher risk groups, it is important to regularly check labs for hyperkalemia to prevent deleterious side effects.