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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.
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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