A middle aged male with a diagnosis of advanced adenocarcinoma of the pancreaticobiliary tree with malignancy related high SAAG ascites who had undergone therapautic paracentesis five days ago presented with complaints of abdominal distension and functional deterioration. He was a known case of Diabetes mellitus (previously on corrective doses of insulin discontinued due to advanced disease and poor oral intake), hypertension (continued only on tapering doses of clonidine 100 ug two times daily) , ischemic heart disease post PTCA and chronic hepatitis B related chronic liver disease (on tenofovir alefenamide 25 mg once daily).

His reports were suggestive of severe hyponatremia (serum sodium 112 meq/l).

Diuretics (spironolactone) were discontinued and he was started on 3 per cent sodium chloride.

A urine sodium, urine potassium and urine osmolarity were ordered. The following values were obtained
Urine sodium – 47.5 meq/l, urine potassium – 48.09 meq/l, urine osmolarity – 404 mosm/kg, urine BUN – 593 mg/dl
Furst ratio – 0.85

What do the laboratory findings represent?
Severe hyponatremia, possibly due to underlying SIADH due to the malignancy and decreased intake.

The patient has reduced oral intake. What about fluid restriction?
Fluid restriction to the extent of 800-1000 ml per day might prove to be beneficial. However acute management requires 3 per cent Sodium Chloride.

What is the threshold beyond which fluid restriction has been shown to be ineffective?
A urine osmolarity of more than 500 mosm/kg as well as a urine sodium more than 130 meq/l.

What would be the specific concerns with use of Tolvaptan in this setting?
Hepatoxicity, fluid restriction will be contraindicated in the first 24 hours of it’s use.

What is the utility of Fractional excretion of Uric Acid (FEUA) in this context?
A cut-off of more than 12 percent denotes increased uric acid excretion which is associated with SIADH and renal salt wasting.

What is the expected plan of management in advanced cancer?
Though it is to be personalised and needs to be in line with goals of care, the following may be considered after discussion with patient and caregiver,
Insertion of tunnelled peritoneal drainage catheter, if survival in months is expected. While repurposed non-tunelled drains such as a pigtail catheter might be considered in those with an expected prognosis of days to weeks, it is important to remember that discomfort due to a drain remains an underreported symptom and might adversely impact the quality of life. Other possible adverse effects include itching, difficulty sleeping and the added psychological burden with the catheter serving as a persistent reminder of their disease.
Potential for intravascular volume depletion, intravenous albumin may be considered at lower volumes of drainage.
Avoidance of repeated rapid or excessive drainage that may precipitate hypotension or circulatory dysfunction.
Small volume paracentesis may be associated with similar relief to removal of larger volumes with lesser metabolic complications.
In this case 1.5 liters may be considered as an acceptable threshold.


References
Ito, T., Yokomichi, N., Ishiki, H., Kawaguchi, T., Masuda, K., Tsukuura, H., Funaki, H., Suzuki, K., Oya, K., Nakagawa, J., Mori, M., & Yamaguchi, T. (2021). Optimal Paracentesis Volume for Terminally Ill Cancer Patients With Ascites. Journal of pain and symptom management, 62(5), 968–977. https://doi.org/10.1016/j.jpainsymman.2021.04.010

Poisson, C., Sampetrean, A., Renard, P., Khoury-Abboud, R. M., Scotté, F., Vigouret-Viant, L., Bonnet, B., Tselikas, L., Deschamps, F., & Mateus, C. (2025). Palliative semi-permanent abdominal drain for the management of refractory malignant ascites: a retrospective study in a comprehensive cancer center. Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 33(6), 496. https://doi.org/10.1007/s00520-025-09551-1

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