Not Your Usual Ascites: A Case of Nephrogenic Ascites

Authors:
Alexander M. Sy, MD; Tova Sofer, MD; and Peter F. Malet, MD

Citation:
Sy AM, Sofer T, Malet PF. Not your usual ascites: a case of nephrogenic ascites. Consultant. 2018;58(8):209-210.

A 64-year-old man was referred to a hepatology clinic for evaluation of ascites. He had type 2 diabetes mellitus, coronary artery disease, hypertension, hyperlipidemia, and end-stage renal disease (ESRD) secondary to diabetic nephro­pathy for which he had been on hemodialysis (HD) for more than 3 years. He had never been on peritoneal dialysis.

The patient had reported progressive abdominal distension over the past few months. He denied fever, chills, nausea, vomiting, jaundice, abdominal pain, melena, and blood in the stool. He reported early satiety in association with his abdominal distension. He was adherent to treatment with HD, which had been scheduled 3 times a week for 4 hours. He was a prior smoker and denied the use of alcohol or other substances.

Prior to initiating HD, he had tested negative for hepatitis B and C and tuberculosis. His medications included aspirin, clopidogrel, gabapentin, insulin glargine, metoprolol succinate, cinacalcet, ezetimibe, and erythropoietin injection during HD.

Abdominal examination revealed large ascites. There were no cutaneous stigmata of cirrhosis and no pedal edema. The rest of the examination findings were unremarkable.

Laboratory tests revealed a hemoglobin level of 8.2 g/dL (reference range, 12.7-18.0 g/dL); a platelet count of 291 × 10³/µL (reference range, 160-392 × 10³/µL); a prothrombin time of 11.7 seconds (reference range, 10-12 seconds); predialysis urea nitrogen and creatinine levels of 78 mg/dL (reference range, 8-21 mg/dL) and 9.4 mg/dL (reference range, 0.6-1.2 mg/dL), respectively; postdialysis urea nitrogen and creatinine levels of 16 mg/dL and 7.0 mg/dL, respectively; an albumin of 3.0 g/dL (reference range, 3.5-4.8 g/dL); and normal levels of liver enzymes.

Urinalysis revealed only +1 proteinuria. Test results for nuclear, smooth muscle, mitochondria, and liver-kidney microsome antibodies were negative. Serum ferritin, ceruloplasmin, and α₁ antitrypsin levels were normal. Additional blood test results are shown in the accompanying Table.

Results of esophagogastroduodenoscopy and colonoscopy done for anemia evaluation were normal. Two-dimensional echocardiography showed an ejection fraction of 40% to 45% with right ventricular systolic pressure of 41 mm Hg, indicating mild pulmonary hypertension and borderline concentric left ventricular hypertrophy. Liver-spleen nuclear scan results were normal with no colloid shift, and abdominal ultrasonography revealed a homogenous, normal sized liver without focal lesions. Doppler ultrasonography demonstrated patent portal circulation.

The patient underwent paracentesis during which 11.3 L of straw-colored ascites were removed. Analysis of the fluid revealed a white blood cell count of 240,000/µL with 3% neutrophils, 9% lymphocytes, and 88% mesothelial cells. Bacterial peritonitis was ruled out based on an absolute neutrophil count of 7/µL. The fluid albumin level was 2.5 g/dL, the total protein level was 7.0 g/dL, and the amylase level was 39 U/L. The serum-to-ascites albumin gradient (SAAG) was 0.5 g/dL.

Results of Gram stain, acid fast bacilli stain, and culture of the ascitic fluid were negative, and cytology test results were negative for malignant cells. Based on the SAAG of 0.5 g/dL, the total protein of 7.0 g/dL, and the absence of peritonitis, liver disease, significant heart failure, and other etiologies of the ascites, a diagnosis of nephrogenic ascites was made.

He was advised to restrict fluid and salt intake. Intensified hemodialysis and ultrafiltration were recommended to his nephrologist. His HD was increased from 4 to 4½ hours per session.

At follow-up several months later in the clinic, his ascites had greatly improved, with a noted decrease in his weight. He was placed on the waiting list for kidney transplant.

NEXT: Discussion

Discussion

In the United States, portal hypertension resulting from advanced liver disease is the most common etiology of ascites.¹ Other causes include malignancy and heart failure. However, patients on maintenance HD may also develop ascites in the absence of any underlying cause, a condition known as nephrogenic ascites. Nephrogenic ascites, also known as ascites associated with kidney failure, nephrogenous ascites, dialysis ascites, and HD-associated ascites, is a rare occurrence owing to improvements in HD technology and care, but its importance lies in the fact that it remains an intractable problem with a life-threatening long-term prognosis if not diagnosed appropriately.

Nephrogenic ascites is a diagnosis of exclusion.^2,3 It was first reported in 1970 by Mahoney and colleagues in patients with ESRD.^2,4 The pathogenesis is unclear but has been hypothesized to be related to uremic toxins, circulating immune complexes, or renin-angiotensin activation.^2,3

Intensive investigation is required to exclude other causes of ascites, such as cirrhosis or severe heart failure, which are the most common causes. Other uncommon etiologies of ascites such as pancreatitis, hypothyroidism, malignancy, and peritoneal diseases caused by infectious agents should also be ruled out. 

Additional diagnostic criteria include straw-colored ascites with a serum-to-ascites albumin gradient of less than 1.1 g/dL, an ascitic total protein content of more than 3 g/dL, a fluid leukocyte count ranging from 25 to 1600 cells/mm³, and negative ascitic fluid culture and cytology results.³

Management includes salt restriction with intense HD and ultrafiltration. Repeated paracentesis and continuous ambulatory peritoneal dialysis have been used but are limited by excessive protein loss and increased risk of infection. Kidney transplant is the definitive therapy.^2,3

Although the incidence is declining due to improvements in HD technology and care, nephrogenic ascites is important to recognize, given that it is usually associated with a grave prognosis. Average survival time ranges from 7 to 10 months, with 44% of patients dying within 15 months of diagnosis.^2,3 

Alexander M. Sy, MD, is a fellow in the Division of Gastroenterology, Hepatology, and Nutrition at NYU Winthrop Hospital in Mineola, New York.

Tova Sofer, MD, was a fellow in the Division of Gastroenterology, Hepatology, and Nutrition at NYU Winthrop Hospital in Mineola, New York.

Peter F. Malet, MD, is the chief of the Center for Liver Diseases in the Division of Gastroenterology, Hepatology, and Nutrition at NYU Winthrop Hospital in Mineola, New York.

References:

1. Runyon BA. Care of patients with ascites. N Engl J Med. 1994;330(5):337-342.
2. Mahoney JF, Gutch CF, Holmes JH. Intractable ascites in chronic dialysis patients [abstract]. Am Soc Nephrol. 1970;4:51.
3. Nayak-Rao S. Nephrogenic ascites—still an intractable problem? Saudi J Kidney Dis Transpl. 2015;26(4):773-777.
4. Hammond TC, Takiyyuddin MA. Nephrogenic ascites: a poorly understood syndrome. J Am Soc Nephrol. 1994;5(5):1173-1177.