A 47-year-old Haitian woman of African decent was referred for nephrotic-range proteinuria and microscopic hematuria. Her blood pressure was 100/70 mm Hg, and physical examination findings were within normal limits, with no evidence of pedal edema. Laboratory testing showed the following values: creatinine, 0.7 mg/dL [62 μmol/L]; estimated glomerular filtration rate, greater than 60 mL/min/1.73 m2 (>1.0 mL/s/1.73 m2); total serum protein, 5.9 g/dL (59 g/L); and albumin, 3.0 g/dL (30 g/L). Urinalysis showed normal-colored urine with protein (3+) and blood (3+), with no red blood cells, white blood cells, fat bodies, or fatty casts. A 24-hour urine collection measured 7,030 mg of protein. A kidney biopsy showed only focal and mild effacement of the visceral epithelial cell foot processes without electron-dense deposits, suggestive of a resolving phase of minimal change disease. She continued to have massive proteinuria and was treated with prednisone with no improvement. Two years later, a repeated kidney biopsy showed similar segmental foot-process effacement with minimal arteriosclerosis and arteriolar hyalinosis. Biopsy findings did not explain the severity of the proteinuria, and the cause remained elusive. A subsequent urinalysis showed turbid white urine (Fig 1), and a retrograde pyelogram was performed (Fig 2).
■ What is the most common cause of this condition and how is it managed?
Discussion
What are the causes of turbid white urine?
Turbid white urine can be secondary to chyluria, hyperuricosuria, phosphaturia, hyperoxaluria, proteinuria, pyuria, lipiduria, and caseous material from renal tuberculosis.1
The cause of white urine in our patient is chyluria. Urinalysis showed evidence of cholesterol, triglycerides, and chylomicrons. Chyluria occurs when there is an abnormal communication between the lymphatic and urinary systems. Chyle is a milky fluid consisting of lymph (which contains 3 to 5 g/dL of protein) and emulsified fats or free fatty acids. It can be confused with nephrotic syndrome when massive proteinuria is present. Chyluria may be intermittent because the white color of urine is caused by the presence of triglycerides and chylomicrons, which acutely vary with diet. Hence, chyluria can be very prominent after a fatty meal and might be absent in a morning urine sample.
What does the retrograde pyelogram show?
In the very proximal segment of the right ureter, there is evidence of a fistula connecting the ureter to small irregular tubular structures within the retroperitonium. The stagnant flow within this structure is consistent with lymphatic channels. The upper collecting system is normal. These findings are consistent with a lymphaticourinary fistula.
The patient's hematuria is likely caused by rupture of small blood vessels during formation of the fistula.1
What is the most common cause of this condition and how is this managed?
Filariasis is one of the most common causes of chyluria worldwide. Other infectious causes of chyluria are tuberculosis and, rarely, schistosomiasis. Noninfectious causes include trauma, tumors, pregnancy, lymphatic abnormalities, thoracic aneurysm, surgery, and mesenteric adenitis.2, 3 The chyluria sometimes may undergo spontaneous remission4 or require surgical treatment.
Our patient had negative test results for filariasis and schistosomiasis. She had not undergone abdominal surgeries and there was no evidence of malignancy. The cause of her fistula remains unknown. Surgery was a possibility, but the patient refused any kind of intervention.
Final Diagnosis
Lymphaticourinary fistula causing chyluria and nephrotic-range proteinuria.
References
1. 1Gulati S, Gupta N, Singh NP, et al.Chyluria with proteinuria of filarial nephropathy? (An enigma). Parasitol Int. 2007;56:251–254. MEDLINE |
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3. 3Garrido P, Arcas R, Bobadilla JF, et al.Thoracic aneurysm as a cause of chyluria: Resolution by surgical treatment. Ann Thorac Surg. 1995;60:687–689. MEDLINE |
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4. 4Ohyama C, Saita H, Miyasato N. Spontaneous remission of chyluria. J Urol. 1979;121:316–317. MEDLINE
Case provided and authored byUma Radha Krishna Pakki Venkata, MD,1 Michael Callum, MD,1 Miriam Neuman, MD,1 Rex Neil Smith, MD,2 and Wayne Trebbin, MD,11North Shore Medical Center, Salem, and 2Massachusetts General Hospital, Boston, MA.
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