Via Research Recognition Day Program VCOM-Carolinas 2025

Case Reports

Cerebral or Renal? Cerebral Salt Wasting in the Absence of Cerebral Disease Nathan Shekey, OMS-III 1 , Mohamed Faris, MD, FACP 2 1. Edward Via College of Osteopathic Medicine – Carolinas, Spartanburg, SC 2. Grand Strand Medical Center, Department of Internal Medicine, Myrtle Beach, SC

Abstract Context : A patient presenting with hyponatremia and evidence of decreased volume status was diagnosed with Cerebral Salt Wasting Syndrome (CSWS) yet lacked evidence of typical central nervous system pathology. This case and others of similar presentation argue that "Cerebral" Salt Wasting should be abandoned for the more appropriate nomenclature of "Renal" Salt Wasting Syndrome. Report of Case : A 72-year-old male presented with nausea, frequent urination, and dizziness. Labs revealed a low sodium level, low serum osmolality, low serum uric acid, elevated urine sodium, elevated NT proBNP, and elevated BUN/Cr ratio. CT imaging of the head was unremarkable, and MRI of the brain revealed mild leukoaraiosis without cortical infarction, blood products, hydrocephalus, or abnormal intracranial enhancement. Comments : A PubMed search revealed 2 case reports of patients with CSWS without cerebral disease, along with one review on the contention between the title "Cerebral" or "Renal" salt wasting. Diagnosis : Given the patient’s clinical presentation, lab findings, and urinary frequency with normal-to-elevated urine volume despite fluid restriction, the diagnosis of CSWS was made. Additionally, elevation in NT-proBNP as seen in this patient may be a factor in the pathophysiology of CSWS. ➢ Hyponatremia is the most common electrolyte abnormality seen in the hospital setting ➢ Causes are often classified by serum osmolality and volume status ➢ CSWS presents with low serum osmolality and low volume status ➢ Elevated brain natriuretic peptide (BNP) has been proposed as a cause of decreased sodium reabsorption seen in previous cases of CSWS (1) ➢ Subarachnoid hemorrhage (SAH), brain tumors, and brain trauma have been correlated in previous CSWS cases (1) This research was supported (in whole or in part) by HCA Healthcare and/or an HCA Healthcare affiliated entity. The views expressed in this publication represent those of the author(s) and do not necessarily represent the official views of HCA Healthcare or any of its affiliated entities. Background

Discussion

Case Summary

➢ 72-year-old white male with one month of nausea, dizziness worsened upon exertion, and multiple urinations per hour. ➢ Medical history: spinal stenosis, GERD, anxiety, and hyponatremia ➢ Home medications: ranitidine (intermittently) and alprazolam (intermittently – not in past month) ➢ Presenting Vitals: BP 186/89, HR 81, RR 18, O2 saturation 100% on room air, oral temp 98.1 ° F ➢ Physical/Neuro Exam: Orthostatic hypotension, otherwise unremarkable ➢ Labs: Hb 13.6 g/dL, Na 129 mmol/L, Cl 99 mmol/L, BUN 42 mg/dL, Cr 0.6 mg/dL, NT-proBNP 780 pg/mL ➢ TSH 0.46 uIU/mL, T4 2.09 ng/dL, morning serum cortisol 15.5 mcg/dL – all within normal range ➢ EKG: NSR with no ST elevation ➢ Echo: LVEF 60-65% ➢ Imaging: CT chest/abdomen/pelvis unremarkable ➢ CT Head: no acute intracranial abnormalities ➢ MRI Brain: mild leukoaraiosis without cortical infarction, blood products, hydrocephalus, or abnormal intracranial enhancement

Etiologic Uncertainty : ➢ BNP is a hormone produced in the cardiac ventricles in response to increased wall tension and arterial pressure, inhibiting renin and aldosterone production and inhibiting sodium reabsorption (2) ➢ In hyponatremic patients with underlying SAH, elevations in BNP have been identified as a potential cause of salt wasting (3,4) ➢ Our patient’s NT -proBNP was elevated to 780 pg/mL without evidence of heart failure Differentiation from SIADH : ➢ Difficult due to shared lab findings: low serum osmolality, high urine ➢ Previous study by Tobin et al found potential utility in NT-proBNP ➢ Claimed diagnosis of CSWS with 87.5% sensitivity and 93.3% specificity (5) Treatment : ➢ Fluid restriction is a major component in treating SIADH (6) ➢ Ineffective in CSWS ➢ Fludrocortisone has shown efficacy in CSWS patients (7) Nomenclature : ➢ Cases of this syndrome in the absence of typical cerebral pathology draw to question the title “Cerebral” or “Renal” Salt Wasting (8,9,10) osmolality, high urine sodium, etc. (1) ➢ Notable difference in volume status: ➢ SIADH - euvolemic/hypervolemic ➢ CSWS - hypovolemic 1. Palmer B. Hyponatremia in patients with central nervous system disease: SIADH versus CSW. TEM . 2003;14(4):182-187. doi:10.1016/S1043-2760(03)00048-1 2. La Villa G, Lazzeri C, Fronzaroli C, Franchi F, Gentilini P. Brain Natriuretic Peptide. Ann Ital Med Int . 1995;10(4):233-241. 3. Berendes E, Walter M, Cullen P, Prien T, Van Aken H, Horsthemke J, Schulte M, Von Wild K, Sherer R. Secretion of brain natriuretic peptide in patients with aneurysmal subarachnoid hemorrhage. Lancet. 1997;349(9047):245-249. doi:10.1016/S0140-6736(96)08093-2. 4. Isotani E, Suzuki R, Tomita K, Hokari M, Monma S, Marumo F, Hirakawa K. Alterations in Plasma Concentrations of Natriuretic Peptides and Antidiuretic Hormone After Subarachnoid Hemorrhage. Stroke. 1994;25(11):2198-2203 5. Tobin G, Chacko A, Rajaratnam S. Evaluation of NT-ProBNP as a marker of the volume status of neurosurgical patients developing hyponatremia and natriuresis. Neurol. India. 2018;66(5):1383-1388 6. Ellison D, Berl T. The Syndrome of Inappropriate Antidiuresis. NEJM . 2007;256(20):2064-2072. doi:10.1056/NEJMcp066837 7. Misra U, Kalita J, Kumar M. Safety and Efficacy of Fludrocortisone in the Treatment of Cerebral Salt Wasting in Patients with Tuberculous Meningitis. JAMA Neurol . 2018;75(11):1383 – 1391. doi:10.1001/jamaneurol.2018.2178 8. Maesaka J, Miyawaki N, Palaia T, Fishbane S, Durham J. Renal Salt Wasting without cerebral disease: Diagnostic value of urate determinations in hyponatremia. Kidney Int. 2007;71(8):822-826. doi:10.1038/sj.ki.5002093 9. Maesaka J, Imbriano L, Ali N, Ekambaram I. Is it cerebral or renal salt wasting? Kidney Int. 2009;76(9):934-938. doi:10.1038/ki.2009.263 10. Bitew S, Imbriano L, Miyawaki N, Fishbane S, Maesaka J. More on Renal Salt Wasting Without Cerebral Disease: Response to Saline Infusion. Clin J Am Soc Nephrol. 2009;4(2):309-315. doi:10.2215/CJN.02740608 References

Consent and Conflicts of Interest

Figure 1. Patient Na level and relevant events/interventions.

➢ Discharged day 12 on 15g urea-Na tablets twice daily for outpatient nephrology follow-up

The patient provided written informed consent during his hospitalization for the utilization of his medical history and clinical findings for research and educational purposes. Patient-specific data were obtained from electronic medical records of Grand Strand Medical Center. The authors declare that they have no financial or competing conflicts of interest regarding this research.

2025 Research Recognition Day

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