Proteinuria (단백뇨) - KMLE 의학 서적: The Root of Ambulatory Care(외래 진료 지침서), 이진우

KEYWORDS: ..성인과 소아에서 하루에 150mg이상의 단백질이 소변으로 배출되는 것을 말 하며, 정상적으로 소변에 배설되는 알부민은 하루 30mg이하이다. 학동기 어린이 : 5~6% 청소년 : 11% Selected populations : 17% Most patients evaluated for proteinuria have a benign cause, fewer than 2% of patients whose urine dipstick test is positive for protein have serious and treatable urinary tract disorders. ..어린이들은 세뇨관 신기능의 미성숙 때문에 소위 생리적 단백뇨가 나오며, 요중 단백질의 배출은 체표면적을 기준으로 할 때 신생아가 가장 많으며, 나 이가 들면서 점점 줄어들어 청소년 말기에는 어른 수준이 된다. Common causes of Benign Proteinuria ..Dehydration ..Emotional stress ..Fever ..Heat injury ..Inflammatory process ..Intense activity ..Most acute illnesses ..Orthostatic(postural) disorder ..무증상 성인에서 단백뇨를 조기에 발견하고 평가함으로써 신질환의 진행을 막을 수 있을지는 미지수이며, 캐나다 예방진료 특별위원회의 지침에서는 인슐린 의존성 당뇨병 환자를 제외하고 무증상 성인의 단백뇨를 발견하기 위해 요 dipstick 검사를 정기 건강검진에서 제외할 것을 권고하고 있다. Proteinuria 511 The Root of ambulatory care Type Pathophysiologic features Cause Primary glomerulonephropathy : Minimal change disease Idiopathic membranous glomerulonephritis Focal segmental glomerulonephritis Membranoproliferative glomerulonephritis IgA nephropathy Secondary glomerulonephropathy: Diabetes mellitus Collagen vascular disorders (e.g., lupus nephritis) Amyloidosis Preeclampsia Infection (e.g., HIV, hepatitis B & C, poststreptococcal illness, syphilis, malaria and endocarditis) Gastrointestinal and lung cancers Lymphoma, chronic renal transplant rejection Glomerulonephropathy associated with the following drugs : Heroin NSAIDs Gold components Penicillamine Lithium Heavy metals Hypertensive nephrosclerosis Tubulointerstitial disease : Uric acid nephropathy, Acute hypersensitivity interstitial nephritis, Fanconi syndrome, Heavy metals, Sickle cell disease, NSAIDs, Antibiotics Hemoglobinuria Myoglobinuria Multiple myeloma Glomerular: most common cause of pathologic proteinuria ( > 2g/24hrs) Tubular : ( < 2g/24hrs) Overflow Increased glomerular capillary permeability to protein Decreased tubular reabsorption of proteins in glomerular filtrate Increased production of low-molecular weight proteins Tests for proteinuria Proteinuria ..Dipstick analysis results : yellow → green (-) : < 10mg/dL (±) trace : 10~20mg/dL (+) : 30mg/dL (2+) : 100mg/dL (3+) : 300mg/dL (4+) : 1000mg/dL False positive : alkaline urine ( >7.5pH), the dipstick is immersed too long, highly concentrated urine, gross hematuria, in the presence of penicillin, sulfonamides, tolbutamide, pus, semen, vaginal secretions False negative : dilute urine (< specific gravity 1.010), nonalbumin proteinuria (low molecular weight) ..Sulfosalicylic acid (SSA) turbidity test : greater sensitivity for proteins such as Bence Jones False positive : In the presence of penicillin, sulfonamides, within three days after the administration of radiographic dyes False negative : highly buffered alkaline urine, dilute specimen ..24 hour urine specimen : discard the first morining void and a specimen of all subsequent voidings should be collected, including the first morning void on the second day - the urinary creatinine concentration should be included in the 24 hour measurement to determine the adequacy of the specimen. (Young & middle aged men ; 16~26mg/kg/day, Women ; 12~24mg/kg/day, In malnourished & elderly persons ; less) ..Urine protein to creatinine ratio : determined in a random urine specimen while the person carried on normal activity. 이 비율은 하루에 배출되는 단백질의 양과 거의 일 치한다. (e.g., 비율이 0.2라면 0.2g/day의 단백뇨를 의미한다.) ..Urine dipstick and SSA tests are crude methods of quantifying proteinuria and should be followed up with a 24 hour urine collection for protein or a urine protein to creatinine ratio. ..Urine protein to creatinine ratio는 외래 환경에서 실용적이며, 최근 연구에 의 하면 24 hour urine specimen보다 더 정확하다는 보고가 있다. 513 The Root of ambulatory care Microscopic urinalysis Trace to 2+ protein on dipstick test Repeat urinalysis 2 to 3 times in next month Quantify proteinuria : 24 hour urine collection, urine protein/creatinine ratio Urine protein excretion < 2g / day Urine protein excretion > 2g / day Creatinine clearance Creatinine clearance Age < 30 years Symptomatic proteinuria Work-up for orthostatic proteinuria Reassure : BP & U/A every 1 to 2years BP. U/A, RFT every 6months Isolated proteinuria Obvious underlying cause Treat underlying disease and follow up every month until stable or creatinine clearance improving Consider nephrology consultation Treat underlying disease : monthly BP, U/A, RFTconsider nephrology consultation Consider nephrology consultation Symptomatic proteinuria Obvious underlying cause Cause unclear Transient proteinuria : Reassure-no further evaluation 3+ to 4+ protein on dipstick test Findings consistent with renal disease (Table 1) : Nephrology consultation (+) (+) (+) (-) Normal (-) (-) Reduced Normal Yes No Reduced Fig 1. Algorithm for evaluating the patient with proteinura Proteinuria Interpretation of Findings on Microscopic Examinaiton of Urine Fatty casts, free fat or oval fat bodies Nephrotic range proteinuria (`>`3.5g/day) Leukocytes, leukocyte casts with bacteria Urinary tract infection Leukocytes, leukocyte casts without bacteria Renal interstitial disease Normal-shaped erythrocytes Suggestive of lower urinary tract lesion Dysmorphic erythrocytes Suggestive of upper urinary tract lesion Erythrocyte casts Glomerular disease Waxy, granular or cellular casts Advanced chronic renal disease Eosinophiluria Suggestive of drug-induced acute interstitial nephritis Hyaline casts No renal disease : present with dehydration and with diuretic therapy ..육안적 혈뇨시 Dipstick urinalysis proteinuria를 보일 수 있으나 현미경적 혈뇨 는 아니다. ▶ The Cockcorft-Gault formula for estimating creatinine clearance. For women, the resulting value is multiplied by 0.85, ideal body weight to be used in presence of marked ascites or obesity. ..Orthostatic proteinuria - 3~5% of adolescents and young adults - 환자가 배뇨한 후 잠자리에 들고나서 일어나기 전까지 8시간 동안 모은 소변과, 일어나서 활동을 시작하고 다음날 잠자리에 들기전에 배뇨할 때까지 16시간 동안 모은 소변의 단백질 양을 측정 (누운자세에서는 단백뇨가 8시간동안 50mg이하로 배설된다.) ..Isolated proteinuria - 10년간 추후 관찰시 고립성 단백뇨는 20%에서 renal insufficiency를 나타낼 수 있어 매 6개 월마다 BP, U/A, RFT가 필요하다. Ccr ＝ (140－age) × body weight (kg) serum creatinine (mg per dl) × 72 515 The Root of ambulatory care Test Interpretation of finding Elevated in SLE Elevated after streptococcal glomerulonephritis Levels are low in glomerulonephritides If normal, helps to rule out inflammatory and infectious causes Elevated in DM Low in CRF that impairs hematopoiesis HIV, hepatitis B and C, syphilis Albumin level decreased and cholesterol level increased in nephrotic syndrome Provide a screening examinaition for any abnormalities following renal disease Abnormal in Multiple Myeloma Elevated urate can cause tubulointerstitial disease Provides evidence of structural renal disease Can provide evidence of systemic disease (e.g., sarcoidosis) Anitnuclear antibody Antistreptolysin O titer Complement C3 and C4 Erythrocyte sedimentation rate Fasting blood glucose Hemoglobin, hematocrit, HIV, VDRL, and hepatitis serologic tests Serum albumin and lipid levels Serum electrolyte (Na+, K+, Cl-, HCO3-, Ca2+, and PO42-) Serum and urine protein electrophoresis Serum urate Renal ultrasonography Chest radiography 참고 문헌 Michael F. Carroll, M.D., Jonathan L. Temte, M.D., Ph.D. : Proteinuria in Adults : A diagnostic approach. A journal of the American Family Physicains 2000 ; 62 : 1333-1340 Joseph J. Lieber: Proteinuria, in Saunders Manual of Medical Practice, 2nd ed, Robert E. Rakel(ed). Philadelphia, Saunders, 2000, P 690-692 심재용 : 단백뇨, in 가정의학 임상편.서울, 계측문화사, 2002, P 1282-1287 Martin S. Lipsky, M.D., Mitchell S. King, M.D. : Proteinuria, in Blueprints in Family Medicine. Massachusetts, Blackwell Publishing, 2003, P 127-129 성균관대학교의과대학 삼성서울병원내과 : 단백뇨. in Handbook of Internal Medicine, 2nd ed.서울, 군자출 판사, 2004, P 456-458