Chyluria is defined as the presence of lymphatic fluid within the urinary tract [
1]. Patients suffering from chyluria typically present with milky and turbid urine, in particular after fatty meals. Urinalysis shows proteinuria which can exceed into nephrotic range while renal function is usually unaltered.
Most cases of chyluria are endemic and due to parasitic infections. The highest prevalence is found in tropical countries where up to 10% of patients with filariasis may experience chyluria [
2]. In contrast, non-parasitic chyluria is a very rare condition most frequently seen in patients with malignancies, following surgical interventions or abdominal trauma or due to congenital malformations of the lymphatic system. The differential diagnosis of milky urine includes pyuria, lipiduria and phosphaturia.
Treatment of parasitic chyluria consists of potent microfilaricidal agents such as diethylcarbamazine [
3]. The largely benign nature and spontaneous remission rates of up to 50% under diet restriction (low fat diet with medium-chain triglyceride supplementation) in non-parasitic chyluria favour a conservative management. Persistent chyluria, however, can lead to malnutrition due to loss of proteins and lipids [
4]. Under such circumstances instillation of sclerosing agents such as silver nitrate solution may induce closure of lymphorenal fistulas with success rates as high as 80% [
5]. However, severe complications such as necrotizing ureteritis and renal failure have been reported with this procedure [
6,
7]. Surgical options include retroperitoneoscopic or surgical renal pedicle lymphatic disconnection [
8].
Case Presentation
A 48-year-old woman was referred to our hospital due to turbid urine, preceded by a three-month lasting episode of macrohematuria.
The patient had suffered from painless macrohematuria in the period from June to September 2010. Onset of hematuria was spontaneous; the first bloody urine was recognized after physical exercise following a hiking tour in the mountains. Treatment with several antibiotics by her local physician did not improve her condition. In July 2010 she underwent urological examination including i.v. urography, cystoscopy and retrograde pyelogram. Computed tomography ruled out a malignant process or signs indicative for pyelonephritis or nephrolithiasis. Gynecological examination was normal. Since macrohematuria persisted, urological work-up was intensified. Bilateral ureterorenoscopy with biopsies taken from a suspicious mucosal lesion within the right lower renal calyx was performed. Histological examination of the specimen showed non-characteristic reactive changes. Invasive angiography of both kidneys excluded an arteriovenous fistula, aneurysm, angioma or vascular malformation.
In August 2010 she was referred to a nephrologist for further evaluation of macrohematuria. Microscopic urinalysis revealed significant hematuria with eumorphic red blood cells without evidence of akanthocytes or red cell casts. Urine sampling revealed nephrotic range proteinuria (14 g/day), urinary protein electrophoresis showed unselective glomerular proteinuria. Notably, the patient had no edema and was only mildly hypoproteinemic (serum albumine 34 g/l). By the end of September 2010, macrohematuria disappeared spontaneously. From this time on, the urine was milky and turbid, only the first morning urine was of normal appearance.
The patient's previous history yielded microhematuria during two pregnancies. During her first pregnancy she had mild arterial hypertension which resolved after delivery. At 28 years of age she underwent surgical treatment for recurrent sinusitis maxillaris. Otherwise, medical history was unremarkable and the patient was on no medication. She had not been outside Europe during the past years.
Vital signs upon presentation were as follows: blood pressure 140/90 mmHg, heart rate 72 beats/minute, respiratory rate 15/minute, temperature 36.5°Celsius. Physical examination was unremarkable; no edema or skin abnormalities were present. Initial laboratory testing was remarkable for hypoproteinemia (total protein 57.9 g/l), hypoalbuminemia (albumin 34.5 g/l) and mild hypercholesterolemia (total cholesterol 242 mg/dl). Whole blood count, serum creatinine (0.71 m/dl) and serum urea (25 mg/d) were normal.
The first morning urine was of normal appearance (Figure , left) and revealed normal ranges for urinary triglycerides (< 5 mg/dl) and albuminuria (24 mg/g creatinine). A postprandial urine sample taken two hours after breakfast was milky and turbid (Figure , right) and revealed increased urinary triglycerides (268 mg/dl) and marked albuminuria (3872 mg/g creatinine). Based on these findings the clinical diagnosis of chyluria was made.
Magnetic resonance imaging revealed bilateral ovary cysts and a right-sided lymphmalformation (Figure ). The exact location of the lymphorenal/lymphoureteral fistula could not be determined. Since there was no immediate need for interventional therapy no further diagnostic work-up was performed and the patient was discharged and advised to maintain a low fat diet.
Prior to discharge a renal biopsy was performed to further clarify the patient's episodic macrohematuria. Light microscopy showed mild mesangial matrix expansion and mild arterio-arteriolosclerosis (Figure ). Direct immunofluorescent staining was negative for immunoglobulines or complement ruling out any immune complex glomerulonephritis. Electron microscopy showed thin glomerular basement membranes (152-203 nm; Figure ). Histological findings were compatible with the diagnosis of thin basement membrane nephropathy.
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