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Abstract: FR-PO913

Fludrocortisone-Responsive Hyponatremia in the Elderly

Session Information

  • Geriatric Nephrology
    November 03, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Geriatric Nephrology

  • 1300 Geriatric Nephrology

Authors

  • Aiumtrakul, Noppawit, University of Hawai'i at Manoa John A Burns School of Medicine, Honolulu, Hawaii, United States
  • Arayangkool, Chinnawat, University of Hawai'i at Manoa John A Burns School of Medicine, Honolulu, Hawaii, United States
  • Tanariyakul, Manasawee, University of Hawai'i at Manoa John A Burns School of Medicine, Honolulu, Hawaii, United States
  • Leesutipornchai, Thiratest, University of Hawai'i at Manoa John A Burns School of Medicine, Honolulu, Hawaii, United States
  • Ng, Roland C.K., University of Hawai'i at Manoa John A Burns School of Medicine, Honolulu, Hawaii, United States
Introduction

Case studies report a rare manifestation of hyponatremia responsive to fludrocortisone, presenting as SIADH or salt-wasting syndrome (SWS), which fails to correct with both fluid restriction and Na replacement.

Case Description

A 79-year-old Japanese woman with T2DM and depression on duloxetine was found to have asymptomatic hyponatremia with Na level of 122 mEq/L. She reported eating 3 meals and drinking water 2 L/day. Vital signs were hemodynamically stable without presence of dehydration. Initial work-up showed serum osmolality at 256 mOsm/kg, urine Na at 94 mEq/L, urine osmolality at 292 mOsm/kg, serum creatinine at 0.4 mg/dL and BUN at 10 mg/dL, with normal serum glucose, AM cortisol and TSH. CT brain without contrast was unremarkable.

Duloxetine was initially held. The patient received 2 L of IV normal saline, followed by NaCl tabs 6 g/day. Fluid intake was restricted to <800 ml/day. The serum Na remained low between 122-126 mEq/L for the next 48 hrs. After initiating fludrocortisone acetate 0.1 mg daily, the serum Na increased to 133 mEq/L within 60 hours, without falling after resuming duloxetine. Her urine output was 1-2 L/day. Her pre- and post-admission weights were 35 and 32.9 kg. Her hematocrit was stable at 34%.

Discussion

Reports in the literature list 10 non-neurosurgical patients with hyponatremia responsive to fludrocortisone, 5 with cerebral salt-wasting, 3 with SIADH, and 2 did not have a clear diagnosis. All of them were Japanese elderly patients. 3 of 10 cases had a prior history of traumatic brain injury.

The clinical response of SIADH or SWS to fludrocortisone is rarely discussed as a treatment of hyponatremia in medical patients. This is another case of fludrocortisone-responsive hyponatremia. Common characteristics include Japanese race, female, elderly, hypo osmolality, hypertonic urine and high urine Na. Volume status can be either hypo or euvolemic. In 1987, Ishikawa et al. proposed the concept of mineralocorticoid-responsive hyponatremia of the elderly (MRHE). MRHE is thought to be caused by a decline in the response to the RAAS and in the kidneys' ability to retain sodium.