• Childhood Kidney Diseases
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• v.21 no.2
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• pp.152-155
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• 2017

Orthostatic or postural proteinuria is the most common cause of asymptomatic proteinuria in children. As orthostatic proteinuria (OP) is a benign disease with relatively good prognosis, it has no specific management, and patients only need to be observed. However, if OP shows a persistently high level of proteinuria, in theory, glomerular changes can occur. An 11-year-old girl was referred to the hospital due to asymptomatic proteinuria and was diagnosed as having OP based on the results of clinical and laboratory examinations, urinalysis, and protein/creatinine (TP/Cr) ratio at both supine and erect positions. During follow-up observation, the 24-hour TP/Cr ratio was persistently higher than 1.5 mg/mg for 2 years. We performed renal biopsy, which showed mesangial proliferative glomerular lesions with focal effacement of the podocyte foot processes, but without immune depositions. OP can be accompanied by glomerular lesions if moderate to severe proteinuria persists.

• Childhood Kidney Diseases
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• v.8 no.1
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• pp.74-79
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• 2004

Orthostatic proteinuria is documented as a benign condition and the most common cause of isolated proteinuria. The etiology and pathogenesis of orthostatic proteinuria is not clear yet. Recently there were a few report that nutcracker syndrome seemed to cause orthostatic proteinuria. We experienced a case of a twelve-yeat-old female patient with incidently discovered orthostatic proteinuria who was suspected to have nutcracker phenomenon by doppler sonography. We confirmed this patient as nutcracker syndrome by renal venography.

• Childhood Kidney Diseases
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• v.10 no.1
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• pp.83-88
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• 2006

Orthostatic or postural proteinuria is a benign condition characterized by the presence of protein in urine samples collected in the upright position during the day and its absence in the supine position. Recently, nutcracker phenomenon has been documented as the source of postural proteinuria. The nutcracker phenomenon refers to compression of the left renal vein between the aorta and superior mesenteric artery, resulting in elevation of pressure in the left renal vein, leading to congestion of the left kidney and occasionally to collateral veins formation. Entrapment of the left renal vein is a cause of left-sided gross hematuria, ureteral and peripelvic varices, unexplained left flank pain and variable degrees of orthostatic proteinuria. We report the case of a 14-year-old girl with orthostatic proteinuria, diagnosed as having nutcracker syndrome by doppler sonography and MR angiography. Because daily protein excretion was more than 1.5 grams over 3 years of follow up, we decided to perform a renal biopsy which revealed moderate mesangial cell proliferation in all glomeruli.

• Childhood Kidney Diseases
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• v.5 no.1
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• pp.64-68
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• 2001

The nutcracker syndrome is the congestion of left renal vein due to the compression of left renal vein by the aorta and the superior mesenteric artery and has been known as tile cause of hematuria with or without left renal flank pain, mild to moderate proteinuria and orthostatic proteinuria. We present here one case of 13.5 year of girl has severe typical nutcracker syndrome with orthostatic protinuria and idiopathic chronic fatigue. (J. Korean Soc Pediatr Nephrol 5 . 64- 8, 2001)

• Childhood Kidney Diseases
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• v.7 no.2
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• pp.142-149
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• 2003

Purpose : The urinary mass screening program for the detection of urinary abnormalities in school aged population has been performed in Seoul since 1981. Nation-wide urinary mass screening program was also performed since 1998. The aim of this study was to analyze the cause and nature of isolated proteinuria detected by chance on the urinary mass screening test in Busan and Kyungsangnam-do Province Methods : The medical records of 44 cases of isolated proteinuria detected by chance on the urinary mass screening test in Busan and Kyungsangnam-do Province, and evaluated for urinary abnormalities at the pediatrics outpatients renal clinics of Busan Paik Hospital from April 2002 to August 2003 were reviewed prospectively. Results : The cause and incidence of isolated proteinuria were as follows; transient proteinuria 4 cases(9.1%), orthostatic proteinuria 36 cases(81.8%) and persistent proteinuria 4 cases (9.1%). The total protein amount of the 24 hour urine were $121.0{\pm}136.4\;mg$ in transient proteinuria, $179.1{\pm}130.0\;mg$ in orthostatic proteinuria and $1532.8{\pm}982.5\;mg$ in persistent proteinuria. In the orthostatic proteinuria group, the total protein amount of the 24 hour urine was in the range of 40-616 mg. Spot urine protein/creatinine ratio(PCR) were $0.10{\pm}0.01$ in transient proteinuria, $0.61{\pm}0.61$ in orthostatic proteinuria and $4.35{\pm}4.04$ in persistent proteinuria. In the orthostatic proteinuria group, spot me PCR was in the range of 0.09-2.32. Renal biopsy was peformed in 4 children of the persisitent proteinuria group. They showed minimal change in 1 case, membranoproliferatiye glomerulonephritis in 2 cases and secondary renal amyloidosis in 1 case. Conclusion : The majority of isolated proteinuria which was detected by chance on school urinary mass screening were transient or orthostatic proteinuria. Even though the incidence of persistent proteinuria was much lower, it is necessary to take care of these children regularly and continuously, because persistent proteinuria itself is a useful marker of the progressive renal problems.

• Childhood Kidney Diseases
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• v.6 no.1
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• pp.61-67
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• 2002

Purpose: The urinary mass screening program in school aged population has been performed since 1981, but the consensus on the follow-up schedule and the management of isolated proteinuria has not been reached yet. The aim of this study was to investigate the cause of isolated proteinuria and to propose a guideline for the treatment and follow-up afterwards Methods: The medical records of 114 cases of isolated proteinuria detected through the analysis of urinary mass screening and evaluated at the pediatric outpatient clinic of Asan Medical Center from January 1990 to July 2001 have been reviewed. Results: The classification of isolated proteinuria was as follows. Transient proteinuria $32\%$, orthostatic proteinuria $65\%$, persistent proteinuria $3\%$, In orthostatic proteinuria group, daytime and nighttime proteinuria were $319.2{\pm}189.1\;mg/dL$ and $56.5{\pm}56.1\;mg/dL$. In persistent proteinuria group, daytime and nighttime proteinuria were $1140{\pm}540.5\;mg/dL$ and $289{\pm}58\;mg/dL$. After 30 month follow-up, 2 cases of persistent proteinuria were needed renal biopsy and 1 case revealed focal segmental glomerular sclerosis. In all cases, serum creatinine, albumin and complements levels were normal. In the orthostatic proteinuria group, no significant renal diseases were detected. Conclusion: Since most of the isolated proteinuria detected through the school urinary mass screening were orthostatic proteinuria or transient proteinuria, initially aggressive diagnostic method such as renal biopsy is not needed and regular follow- up with quantitation of proteinuria is warranted.(J Korean Soc Pediatr Nephrol 2002 ; 6 61-7)

• Childhood Kidney Diseases
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• v.21 no.2
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• pp.53-60
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• 2017

Proteinuria is common in pediatric and adolescent patients. Proteinuria is defined as urinary protein excretion at levels higher than $100-150mg/m^2/day$ in children. It can be indicative of normal or benign conditions as well as numerous types of severe underlying renal or systemic disease. The school urine screening program has been conducted in Korea since 1998. Since then, numerous patients with normal or benign proteinuria as well as early stage renal diseases have been referred to the hospital. Benign proteinuria includes orthostatic proteinuria and transient proteinuria. Most causes of proteinuria can be categorized into 3 types: 1) overflow, 2) tubular, and 3) glomerular. Although treatment should be directed at the underlying cause of the proteinuria, prompt evaluation, diagnosis, and long-term monitoring of these pediatric patients can prevent potential progression of the underlying disease process. This article provides an overview of proteinuria: its causes, methods of assessment, and algorithmic suggestions to differentiate benign from pathologic renal disease.

• Childhood Kidney Diseases
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• v.14 no.1
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• pp.84-88
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• 2010

Posterior nutcracker phenomenon (PNP) was found to be the cause of significant proteinuria in a 10-year-old female. PNP was documented by Doppler ultrasonography and abdominal 3D CT as a cause of her proteinuria. Despite treatment with ACE inhibitor for several months, her persistent and progressive proteinuria lead us to perform a left renal biopsy, which revealed no significant finding except for focal effacement of foot processes. We speculate that nutcracker phenomenon can induce not only orthostatic proteinuria but also significant proteinuria by focal effacement of foot processes.

• Childhood Kidney Diseases
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• v.7 no.2
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• pp.125-132
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• 2003

Purpose : Lipoprotein(a) is a genetically determined risk factor for atherosclerotic vascular disease and is elevated in patients with renal disease. Especially the patients with nephrotic syndrome exhibit excessively high Lp(a) plasma concentrations. Also the patients with end-stage renal disease have elevated Lp(a) levels. But the mechanism underlying this elevation is unclear. Thus, in this study, by measuring the level of serum Lp(a) in common renal diseases in children, we hoped to see whether there would be a change in Lp(a) in renal diseases other than nephrotic syndrome. Then, we figured out its implications, and looked for the factors that affect the Lp(a) concentrations. Methods : A total of 75 patients(34 patients with hematuria of unknown etiology, 10 with hematuria and hypercalciuria, 8 with IgA nephropathy, 8 with poststreptococcal glomerulone phritis, 3 with $Henoch-Sch\"{o}nlein$ nephritis, 7 with urinary tract infection, and 5 with or- thostatic proteinuria) were studied. The control group included 20 patients without renal and liver disease. Serum Lp(a), total protein, and albumin levels, 24-hour urine protein and calcium excretions, creatinine clearance and the number of RBCs and WBCs in the urinary sediment were evaluated. Data analysis was peformed using the Student t-test and a P-value less than 0.05 was considered to be statistically significant. Results : LP(a) was not correlated with 24-hour urine calcium and creatinine. Lp(a) level had a positive correlation with proteinuria and negative correlation with serum albumin and serum protein. Among the common renal diseases in children, Lp(a) was elevated only in orthostatic proteinuria (P<0.05). Conclusion : Lp(a) is correlated with proteinuria, serum protein, and serum albumin, but not with any kind of specific renal disease. Afterward, Lp(a) needs to be assessed in patients with orthostatic proteinuria and its possible role as a prognostic factor could be confirmed.

• Childhood Kidney Diseases
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• v.3 no.2
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• pp.161-169
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• 1999

Purpose : The urinary mass screening program for the detection of proteinuria in school aged population has been performed in Seoul since 1981. Systematic evaluation in corporation with the Seoul School Health Center for students with proteinuria identified in the mass screening has been performed from 1987. The results of urinary mass screening up to 1994 was reported. I report here the results of urinary mass screening from 1995 to 1997 and compare them with previous results and attempt to reveal the significance of urinary mass screening. Objects and Methods : In the 3-year period between 1995 and 1997, annually about 460,000 students comprising 3 different age groups; 5th grade of elementary school, 2nd grade of middle school and 2nd grade of high school were chosen, corresponding to the approximate ages of 11, 14, and 17 years, respectively. These subjects accounted for 26% of total school aged children in Seoul. The screening program was carried out in 3 steps. The 1st test was performed with dipstick at school and the 2nd at the Seoul School Health Center. Those students who showed proteinuria in the 1st and 2nd tests were referred to the hospital. Laboratory examinations including renal biopsies were performed to those students with pathologic proteinuria to clarify the incipient renal diseases. Results : 1) The prevalence of asymptomatic proteinuria was 0.28% in the 1st test. It peaked at the group of 14 years old as 0.34%, compared with 0.26% at the group of 11 years old and 0.24% at the group of 17 years old. It reached to 0.26% in male and 0.30% in female. 2) 25 percent of those having proteinuria at the first test were positive at the second test. 3) The proportion of patients with proteinuria by 3rd test were as follows; 25% of transient proteinuria, 55% of orthostatic proteinuria, 6% of constant proteinuria, 12% of proteinuria with hematuria, and 2% of transient proteinuria with isolated hematuria. Pathologic proteinuria were totaled as 20%. The prevalence of renal diseases among the age group of 7-18 years old was estimated to be 1.4 per 10,000. 4) Renal biopsy performed on 38 children with proteinuria at the third test revealed IgA nephropathy in 17(44%), focal segmental glomerusclerosis in 5(13%), minimal change disease in 4(11%), membranoproliferative glomeronephritis in 3(8%), $Henoch-Sch\"{o}nlein$ purpura nephritis in 3(8%), and others in 6(16%). Therefore, the prevalence of IgA nephropathy among the age group of 7-18 years old was estimated to be 0.64 per 10,000. 5) The prevalence of chronic renal failure was estimated to be 5.7 per 1 million of 7 to 18 years age group. Conclusions : 1) The prevalence of proteinuria in the first screening test was 0.28% and finally only 5% of them showed the pathologic proteinuria at the third test. 2) The prevalence of IgA nephropathy and chronic renal failure were 0.63 per 10,000 and 5.7 per 1 million, respectively among school-aged children in Seoul.