Basic laboratory tests
in renal diseases
Jana Granátová
Dept. of clinical chemistry,
Thomayer Hospital
and 3rd Medical Faculty of Charles University
ONLY FOR EDUCATIONAL PURPOSE FOR STUDENTS
OF THE THIRD FACULTY OF MEDICINE 1
!!!
Useful references:
• The presentation
• Important numerical values
• Basic laboratory tests – practical advices („a cookery – book“)
• https://sites.google.com/site/nphrologic/Home/course-8edema-and-renal-disorders
2
When and whom to examine?
• asymptomatic population: 17% with GFR < 1,0 ml/s, renal
disorder = preexisting risk
• pre-operative (peri-, postoperative complications)
• potentially nephrotoxic therapy (aminoglycosides, contrast
media, nonsteroid antiinflammatory drugs)
+ age, diabetes, hyper/hypotension, combined therapy
• drug administration (doses cumulation)
• Diseases that can damage kidney - diabetes, hypertension,
cardiovascular diseases
• long-term observation in renal diseases
3
Glomerular filtration rate
(GFR)
4
•
•
a basic test of renal function
severity of damage:
- chronic - K/DOQI classification (Kidney Disease Outcome Quality Initiative)
appropriate therapy, drug administration, indication to renal
replacement therapy, predialysis care
CKD stage
1
GFR (ml/s/1,73m2)
≥ 1,5
normal GFR + kidney damage (PU, HU)
2
„mild renal insufficiency“
1,0 – 1,49
3
„moderate renal insufficiency“
0,50 – 0,99
4
„severe renal insufficiency“
0,25 – 0,49
5
kidney failure, ESRD/RRT
< 0,25
(mild, moderate, severe renal insufficiency – descriptive - no definition,
no clinical classification)
- acute – RIFLE criteria (s-creat., GF, urine output)
5
Glomerular filtration rate
ultrafiltrative pressure (blood flow in the kidney), filtrative area, number of
nephrons
• approx. 2 ml/s/1,73m2
lower in female
• physiological decrease with age 0,17 ml/s/1,73m2/10 years
(80 – 90 y. = 50 % of function in 20 y.)
• decreases in kidney disease – acute (AKI) and chronic
chronic kidney disease (FSGS): decreased number of nephrons,
compensatory residual hyperfiltration
… overload, nephron death, fibrosis….progressive worsening, fall in GF
• indirect indicator = renal clearance (plasma volume cleaned off from
substance XY in a time unit)
6
Renal clearance
GF = clearance + tubular secretion (or - tubular resorption)
• Clearance of inulin: a golden standard, GF = Cin, not for
daily practice
• Radionuclid methods: 99mTc-DTPA, 51Cr-EDTA,
125I-thalamate
- more accurate (drop in plasma after i.v. administration)
- both the kidneys separately (before kidney transplant.,
stenosis of a. renalis)
7
Clearance of endogenous creatinine, Ccr
- daily 1-2 % creatine (muscles, brain) → creatinine (liver)
- free filtred + secreted in tubuli
(physiologically 10 % x in a chronic kidney failure > 100%,
+ excreted through a gut)
- as decreased GF, as overestimated Ccr
- calculation based on u-creat., urine volume, time period (24 h),
s-creat.
- adjusted to body surface (weight, height) – ml/s/1,73m2
- reference values: 1,5 – 2,0 ml/s/1,73m2 (gender, age)
females: 8 - 10% lower
8
- limitations:
- to collect urine correctly
better in a hospital stay (x confused collecting vessels)
(outpatient dpt.: 40% pts. differ > 30% in collected
volume = more than 50% in calculated GFR value)
-
low muscle mass (low s-creatinine)
obese, fluid retention, swellings (creatinine distribution)
short time of collection (circadial rythms)
urine output < 500 ml / 24 h
- less realiable in late stages of CKD (overestimated GF)
9
S-creatinine
• elevated:
- low excretion: altered structure of kidney (glomerulonephritis,
interstitial nephritis, obstruction, malformation,…)
- functional: altered renal perfusion (hypoxia, severe cardiac
insuficiency,…)
- high production (polytrauma, acromegalia,…)
• muscle mass, physique, diet, physical excercise, hydratation
REMEMBER: TO SEE YOUR PATIENT !!!
• limitations:
- muscle atrophy (age, immobilization, malnutrition)
- swellings, hyperhydrated patient, (pregnancy)
- rapid changes (biological half-time 24 h!) – critically ill patients
(s-cystatin C, u-NGAL are better )
Reference values:
male: 62 – 115 µmol/l
female: 53 – 97 µmol/l
10
• non-linear dependence s-creat. and GFR (hyperbolic)
• a late indicator of kidney damage (GFR ≤ 50% = CKD-3)
• not to use for early diagnostics of decreased function
(nephrotoxic therapy, early therapy)
• only 6/10 with slightly decreased
GFR has increase in s-creat.
CYSTATIN C
„creatinine-blind“
CREATININE
11
s-cystatin C
• produced by all nuclear cells at a constant rate
• serin proteases inhibitor
• free filtered in glomeruli + completely resorbed + metabolized
in proximal tubuli
• its concentration in serum = glomerular filtration
• estimated GFR (Grubb: eGFR = 1,412 x Scyst. -1,68 x F)
• EARLIER INCREASE THAN S-CREATININE
• an early indicator of decreased GF („creatinine-blind “, GF 50 – 99%)
• independent on age, muscles, height and weight
indication: children, elderly, long-term immobilized, nephrotoxic therapy
muscle atrophy, cachexia, pregnancy
limitations:
- steroid therapy („worse“ GF)
Δ 25 – 50 %, evaluate with s-creat., dependent on a dose
12
- decompensed thyroid function („better“ in hypofunction)
Estimated GFR (eGFR)
THE ONLY S-CREAT. IS INACCURATE AND LATE
S-creat., age, gender, (black/other), without an urine collection
recommended together with s-creatinine if it is standardized (enzymatic)
calculators
(www.kidney.org/professionals/tools/index.cfm)
„value“ + clinical conditions, patient´s individuality
≥ 1,5
- „normal“, higher values not given (underestimate -15-17%)
1,0 – 1,49 - to evaluate individually (age, clinical conditions)
< 1,0
- pathological (LM: in screen - if 0,67 ml/s/1,73m2: CKD 3 – 5
in > 90% pts., AUC 0,97 for CKD 3- 5)
not to use: -
rapid sudden changes
pregnancy
muscle atrophy (s-creat. < 40 µmol/l)
young, healthy
13
adults:
• MDRD formula:
eGFR = 515,3832 x (s-creat)-1,154 x age-0,203 x F1 (x F2)
• CKD-EPI formula:
female: eGFR = 144 x (S-creat. / 62-F) x 0,993age , F: S-creat < / > 62 μmol/l
male:
eGFR = 141 x (S-creat. / 80-F) x 0,993age
F: S-creat < / > 80 μmol/l
• Lund-Malmö formula:
eGFR = eX - 0,1124 x age + 0,339 x ln(age) – 0,226 (if female)
X= 4,62 – 0,0112 x (s-creat), if < 150 μmol/l
X = 8,17 + 0,0005 x (s-creat) x ln(s-creat.), if >150 μmol/l,
(correct. To LBM (lean body mass)
• (Cockroft – Gault: age, weight, s-creat., gender – not recommended)
14
Formulas are relatively comparatible:
MDRD:
better: for GF 0,5 – 1,0 ml/s/1,73m2
worse: elderly > 80 let (+18%)
CKD-EPI: better: for GFR 1,0 – 1,5 ml/s/1,73m2 (differs at 10 - 12 x 17%)
for general screen, elderly
the both are inaccurate:
- in young, healthy individuals (CKD-EPI +22%, MDRD +14%)
- in males with low BMI < 20 (CKD-EPI +36%, MDRD +46%)
- if GF < 0,5 ml/s/1,73m2
- in children
LM:
better: for GFR near to 1,5 ml/s/1,73m2
for GFR < 0,5 ml/s/1,73m2
can be used for children older 1 y.
15
children:
• Schwartz: s-creat., age, gender, height
eGFR = (F. height) : s-creat.
• based on cystatin C (the same as in adults)
•
Lund-Malmö (the same as in adults)
• maximal s-creatinine: height (cm) x 0,54
= the highest „normal“ s-creat . value fitted to „normal“ GF (1,5 ml/s/1,73m2)
(3 years = approx. 100 cm: 54 μmol/l x 2 years = 86cm – 46,5 μmol/l f.e.)
16
Závěr do praxe 1:
Chci v praxi vědět, jakou funkci ledvin má můj pacient?
Dospělý „běžný“ pacient : S-kreatinin (+odhad GF)
(eGF: MDRD, event. CKD-EPI, Lund-Malmö)
•
•
•
•
kreatinin ne → S-cystatin C (+ odhad GF z cystatinu):
funkce štítné žlázy???, steroidy???
svalová atrofie (kachexie, po imobilizaci, dystrofie, senioři) / muskulatura
těhotná
extrémně obézní
pro dávkování léků
Dítě: S-cystatin C (fyziognomie, svalová atrofie /dystrofie, věk)
s-kreatinin (+ eGF-Schwartz nebo Lund-Malmö,
ne MDRD/CKD-EPI),
orientačně maximální S-kreatinin
diagnosis and management of AKI
Traditional diagnosis:
- rise in s-creatinine
(24 – 72h, fluctuating,
50% of function lost)
- fall in GF
- fall in urine output
(!! non-oliguric AKI)
- changes in a function
NGAL:
NGAL
- real-time (30 – 120 min)
- changes in a structure
From: Vaidya, et al. Ann Rev Pharmacol Toxicol 2008
18
NGAL
(neutrophil gelatinase-asscociated lipocalin)
•
•
•
•
physiologically in neutrophile granules – binds iron – bacteriostatic effect
produced early after the renal insult by epithelial cells in distal tubuli
significan rise in 2 – 4 hours after nephrotoxic, ischemic insult
functions:
- protective: early, protects/reduces tubular epithelium damage
- proliferative: late, growth and differentiation of new tubular cells
• predicts the development of AKI on 2 days earlier than s-creat.
(sepsis, major operations, cardiogenic shock, nephrotoxins,…)
• proportional reponse to injury, no differentiation in causes
• measured in urine, results early (till 1 hour)
• indications: ICU patients, major operations, cardiac surgery, contrast
induced / cis-Pt nephropathy, graft recovery prediction
19
s-urea (blood nitrogen)
• protein metabolism (NH2) end-catabolite, in liver
• excreted 90 % in kidney: GF + tubular resorption (30 – 40%),
(+ gut, skin in chronic kidney failure)
• increase not only if damaged kidney
-
high protein intake
catabolism (fever, sepsis, starvation, bleeding)
hydration (volume depletion)
congestive heart failure
• increases later than s-creatinine (if GF < 30%)
• faster and more in dehydrated and volume depleted patients
• diff. dg prerenal x renal causes of renal failure:
prerenal: ↑ s-urea > > ↑ S-creat., ↑ u-urea, ↑ u-osmol.
• reference values: 1,7 – 8,3 mmol/l
20
Závěr do praxe 2:
Podezření na postižení ledvin – běžný pacient, susp. chronické onemocnění:
S-kreatinin (+ eGF: MDRD, event. CKD-EPI, Lund-Malmö)
S-urea, albumin v moči - ACR (je-li diabetik, hypertonik)
Podezření na akutní poškození ledvin (AKI):
Ambulant: trend s-kreatininu 3- 4 dny (event. cystatin C, viz výše)
pokračující trend → hospitalizovat
cave:
biologická + analytická variabilita s-kreat. mezi dny cca 15%
změny s-kreatininu se zpožděním 24 – 48h po inzultu
Hospitalizovaný: S-cystatin C, (event. NGAL)
Proteinuria
(PU)
22
The kidney:
→
very efficiently ultrafiltrates water, mineral and small molecules
→ efficiently restricts protein loss from plasma to ultrafiltrate
(recirculation, resynthesis)
blood flow rate at 1,2 l / min → daily 40 - 50 kg albumine
→ 2 - 3 g/d into the ultrafiltrate
→ only 30 mg/d into a definitive urine
glomerular wall integrity, tubular resorption, physical-chemical
characteristics of proteins, microcirculation in glomeruli
23
The glomerulus wall
Endothelium negatively charged
Base membrane – 3D sieve,
loops – diameter, negatively
charged
Podocytes – amount of water (and
protein) passing through a
glomerulus wall
24
Proteinuria:
• transient: functional – in healthy kidneys
- excessive physical excercise, severe stress
- orthostatic: in a standing, not in a lying position,
till adolescence, asthenic physique,
other laboratory tests normal, observe
• persistent: repeately, always observe
- kidney disease, even if normal GFR
• a sign of kidney / urinary tract disease
• an independent risk factor
25
Protein in urine
– urinary strips
• different limit of detection: 0,15 - 0,30 g/l, low reliable
• concentration of proteins in urine, dehydration/polyuria
false negative: other proteins than albumine (tubular proteins
– interstitial nephritis, myeloma)
false positive: dehydrated, hematuria, pH > 7-8,
disinfectants, artificial (malingerers)
• A NEGATIVE RESULT DOESN´T EXCLUDE
PATOLOGICAL PROTEINURIA
(normal total protein amount + patological composition,
other proteins than albumin,
26
proteinuria ≤ 15 g/mol creat. - in 1/3 pathological composition)
• NOT FOR EARLY DIAGNOSTICS
(early stages not detected, no intervention, no prophylaxis)
• not recommended for screen or follow-up
(low reliability of changes in a semiquantitative scale)
•
if positive ≥ 1+ → a quantitative test
•
plus a test with 20% sulfosalicylic acid (the same reaction
with all proteins in urine, „confirmation“ of a negative result)
Proteinuria = risk factor – renal (ESRD)
and cardiovascular (mort., morbid.)
27
Proteinuria - quantity:
• physiological:
previously: ≤ 0,150 g/d (0,07 - 0,10 g/l) - consensual
now: adjusted to u-creat. - PCR (protein-to-creatinine-ratio)
≤ 15 g/mol creat
• pathological:
mild
moderate
high
nephrotic
< 1 g / 24 h
1 - 3 g /24 h
> 3 g /24 h, PCR > 100 g/mol
> 3,5 g/24 h
nephrotic PU = a risk of nephrotic syndrome (NS)
NS = nephrotic PU + clinical and laboratory signs
(swellings, low s-albumin, low s-total protein, dyslipidemia
(↑cholesterol, later triglycerides), accelerated atherosclerosis,
28 (children)
thromboembolic complications (adults), infection
Microalbuminuria:
• mild elevated urinary albumin undetectable by ususal
urinary strips (< < 150 mg/l)
microalbuminuria strips: limit of detection 30 - 40 mg/l - for GP (positive)
• measure quantitative - ACR (mg/mmol creat.)
ACR: albumin-to-creatinine-ratio
(not recommended in ug/min, mg/l, mg/d)
• a random urine sample, not collected urine
• physiological values: < 2,6 mg/mmol (male),
< 3,6 mg/mmol (female) – lower?
• microalbuminuria: ACR 2,6 (3,6) – 29,9 mg/mmol
(30 mg/l)
29
MAU = elevated cardiovascular and renal risk
• elevated risk also in high normal albuminuria
(higher than 2 mg/mmol in male / 3 mg/mmol in female)!
Incidence of ESRD and albuminuria – 10,3 r.
follow-up, HUNT-2 (Hallan et al, JASN 2009)
cardiovascular morbidity
30
and mortality / 5 years, LIFE
• not to test:
- urinary tract infection,
- after physical exercise
- menses,
- if positive protein in urinanalysis,
- in acute diseases
• high variability in excretion (CVi 30%) - to test repeately
• criteria: positive in ≥ 2/3 tests in 3 - 6 months
• recommended to test regularly in:
- hypertension,
- diabetes
- cardiac ischemia
31
Microalbuminuria in diabetes (DM):
DM+MAU = a sign of incipient nephropathy (stage 2-3 from 5)
10x higher risk of ESRD
4x cardiovascular complications
2x total mortality / 5 years
DM-1: 50% MAU → 80% dia nephropathy (DN) with PU
50% without MAU → vascular changes
DM-2: 40 - 50% MAU, manifest DN in fewer patients,
more often nephrotic syndrome
good metabolic control, corrected hypertension, ACEI
= to reduce / stop the progression to renal failure
screen: 1x in a year,
- DM type 1: in 5 years after the diagnosis is given,
- DM type 2: immediately
32
PU composition – PU types:
indication:
- diff. dg. (f.e. PU 1 g/l – cause: GN / DM, HT / TIN?)
- new PU (esp. in young, with a nephrotic sy, typical
diagnosis and atypical findings)
PU in DM: 30 – 50% = other than dia nephropathy
- indication to renal biopsy (profit x risks)
- „replacement“ of renal biopsy if RB is not possible / at risk
- how much altered – progression - appropriate therapy
(conventional x immune-supressive)
- therapeutic response, compliance
33
Proteinuria types:
according to its composition:
- glomerular
- tubular
- mixed (glomerulo-tubular)
- prerenal
- (postrenal)
• qualitative pattern
(electrophoresis in urine)
• quantitative (some excreted proteins)
albumin, IgG, α1microglobulin
+ ratios, graphs, cut-off values
34
Physiological PU:
• selective glomerular filter (charge, large, Mr, shape)
Mr < 67 kD (albumin)
• tubular resorption (99%)
• secretion
• 50 - 80 mg / 24 h
• consensually 150 mg / 24 h
• PCR ≤ 15 g/mol creat.
uromodulin, THP 30 - 50 mg
albumin
10 - 30 mg
sIgA
10 - 15 mg
polyclonal light chains
10 - 15 mg
Schneiderka P.: Vybrané kapitoly z klinické biochemie
35
Glomerular PU:
altered glomerular filter
selective PU:
• loss of a negative charge
• albumin, (transferin)
• minimal change nephritis,
early stages of glom. diseases
• better prognosis
nonselective PU:
• more severe wall alteration
– large molecules are passed
• albumin, IgG
index of selectivity : IgG / Alb
≤ 0,03 - selective PU (MCN,
response to steroids)
> 0,04 – nonselective
36
Tubular PU:
altered tubular resorption
• mild PU (less than 1 g/d)
• microproteins (Mr < albumin)
α1microglobulin, β2micro, RBP,
• strips often negative
(sulfosalicylic acid positive)
• toxins (cisPt, aminoglycosides,
heavy metals, X-ray contrast,
toxins), ischemia, hypoK,
hyperCa, hyperuricemia, acute
obstruction, inflammation
• also a late consequence of
glomerular PU (tubular atrophy
+ fibrosis) - advanced changes
37
Mixed PU:
advanced disease (glomerular, systemic disease, severe
chronic interstitial nephritis)
tubular cells and glomeruli are altered by PU - toxicity of PU
(glomerular sclerosis, atrophy of tubuli, sterile inflammation,
nephrons are replaced by interstitial fibrosis)
• moderate / heavy, nonselective
• albumin, IgG + α1microglobulin, and other proteins, …
• as higher PU, as faster progression
• in DM, HT earlier than in GN
38
1 – normal tissue
2 – mild fibrosis and atrophy
3 – moderate fibrosis and atrophy
4 – severe fibrosis
and atrophy
39
Prerenal PU:
healthy kidney initially
+ ↑↑↑ microproteins from blood
(monoclonal light chains,
hemoglobin, myoglobin)
overestimated capacity of
tubular resorption
• strips often negative
(sulfosalicylic acid positive)
• myeloma, intravascular
hemolysis, muscle contusion,
catabolism, fever, inflammation,
tissue necrosis
• leads later to altered tubuli
40
Postrenal PU:
proteins secreted in a lower
urinary tract
• mild (less than 0,5 g/d)
• dominates leucocytes +
hematuria
• typical: α2-macroglobulin, IgG
• inflammation, trauma, tumors
41
Patient 1: 25 y., male:
1/2011: 2 weeks ago tonsillitis (antibiotics) + cold
clinical: fatigue, mild hypertension
lab.:
S-creat. 140 … 168 µmol/l, border Ckr 1,82 ml/s/1,73m2,
urinanalysis: active sediment (ery ++++, leucocytes ++, casts)
microHU, PU 2,8 g/l
elevated C3+C4, ASLO normal, negative autoantibodies (ENA, ANA,…)
suspected: acute GN (post-infectious)?
•
•
•
•
children 3 – 10 y, young, 10% > 60 years
infection in a history (bacterial, viral, toxopl., parazit.),
may be asymptomatic - only with HU,
↑ ASLO (anti-DNase, anti-hyaluronidase),
PU 0,5 – 2 g/d, mixed nonselective
↑ S-creat, active sediment (erythrocytes + casts, leucocytes),
42
↓C3+C4, ↑ CIK, cryoglobulin
PU typing: PU 2,8 g/l,
↑↑↑ albumin, ↑ IgG + ↑ transferin, normal a1micro, IgG/Alb. 0,07
Concl.: glomerulonephritis with glomerular nonselective PU,
without tubulo-interstitial damage, glomerular HU
renal biopsy: IgA nephropathy with crescents 30%, active form
IgA nephropathy: always hematuria
- repeately macroHU (respiratory, intestinal infecton) + mild PU,
with/without renal insuficiency,
- proportional PU a HU, as higher PU, as worse prognosis
- asymptomatic microHU (without PU / mild PU),
- in all age, children and young, more often males (6x)
- PU < 1 g/l, if PU > 1,5 g/l (10 - 15%) – steroid therapy
- correct diagnosis → renal biopsy
- appropriate therapy: acute GN – non specific, if steroids – worse reparation
x IgAN mild form – regime, active form / heavy PU –43imune-supressive
Patient 2: 26 y., male:
2004 minimal change nephritis, MCN (RB), nephrotic sy, imune-therapy,
repeated relapses (the last one month ago)
MCN: fusion of podocate pedicels + regressive changes,
normal glomeruli; normal GFR
develops fast nephrotic PU without microHU,
children 2 – 7 y., in adults rare, worse prognosis (relapses)
typical: glomerular selective PU: selectivity – effective steroid therapy
1/2011 admission to hospital – worsening conditions – relapse? other?
swellings of both lower extremities, rise in PU
s-creat. 86 µmol/l, urea 10,6 mmol/l, low total protein (38 g/l), very low
albumin (16 g/l), high cholesterol (9,4 mmol/l), high triglycerides (4,5 g/l),
very low IgG (< 1,4 g/l), IgA + IgM norm., PU 3,6 g/l (10,1 g/d)
PU typing :↑↑↑↑ albumin, ↑ IgG, norm. a1micro, IgG/Alb. 0,008
Concl.: GN with glomerular high selective PU, without altered interstitium,
without microHU
another relaps – effective steroids:
44
in 5 days: total protein to 53 g/l, albumin to 35 g/l, PU drop to 0,13 g/l
Patient 3: 52 y., female
2 weeks ago abdominal pains, fatigue, anorexia, diarrhea, dyspnea,
S-krea 253 ... 410 µmol/l (in 4 days !), elevated CRP (144…129 g/l),
inflammation and acute obstruction excluded
suspected rapid progressive GN (RPGN) → renal biopsy
rapid progressive GN (RPGN):
HU + PU + rapid fall in glomerul. function (> 50% / 3 mths, crescents > 50%
- vasculitis (c-ANCA+) – Wegener granulomatosis
- immune-complexes (post-infectious, collagenosis, other GN)
- anti-GBM-nephritis (without/with pulmonal damage – Good-Pasture sy)
- can complicate any GN
weakness, fatigue, fever, anorexia, abdominal pain, swelling of joints,
(viral infection in the history)
if not treated, in 3 months progression to ESRD
45
S-krea 871 … 532 … 242 µmol/l (10 days), normal value in 4 months
urea 24,9…28,9…17,3 mmol/l, elevated s-K+ (6,1 mmol/l), elevated s-P+
elevated s-CK, very high myoglobin (non-cardial),
urinanalysis: protein +, blood ++, erythrocytes 5/ul, leucocytes 44/ul
CRP 84…120,8…9,3 mg/l, elevated s-LD, high s-IgE (486…227)
metabolic acidosis (pH 7,276, BE -11mmol/l)
blood count: low Hb 86…120…83 g/l, eosinophiles
PU typing: mild PU 0,16 g/l: ↑↑↑ α1-microglobulin, ↑ albumin
Concl.: interstitial nephritis, interstitial mHU
renal biopsy: acute interstitial nephritis
Concl.: acute kidney failure - aTIN hypersensitive
+ rhabdomyolysis, hemolytic anemia, iridocyclitis,
good response to steroids
rhabdomyolysis: ↑s-CK + myoglobin, urinanalysis: blood ++, low ery
hemolysis: ↓ Hb, ↑ s-LD, hypersensitivity: eosinofiles, high IgE
AKF (s-creat. + urea)+ altered tubular functions: ↑ P; ↑ K, metabolic acidosis
46 functions
diff. dg AKF (GN x TIN), therapy, early diagnosis → repaired
Urinanalysis
(chemical and morphological)
47
• results dependent on the quality of samples
(middle stream of morning urine, hygiene, not if menses)
• analyze to 1hour (changes in pH, destroyed elements)
• diagnostic strips
• semiquantitative scale
• pH, specific gravity, protein, leucocytes, glucose, nitrites,
blood/erythrocytes, ketones, bilirubin, urobilinogen
48
pH in urine:
usually: 5 – 6,5
• possible 4,5 – 8,0 (strips, pH-meter)
• changes in pH - acidobase regulation
• alkalic pH (> 7):
- vegetarians,
- alkalizing therapy (diuretics, secondary prophylaxis
of urolithiasis, hyperuricemia),
- vomiting
- prolonged storage
x - bacterial infection
- compensatory in metabolic alkalosis
- renal tubular acidosis
49
(altered HCO3- resorption and acid urine production)
Blood in urine - strips:
• positive: erythrocytes / free hemoglobin / myoglobin (hem)
erythrocytes - urinary tracts, kidney disease, bleeding
hemoglobin - destroyed erythrocytes, intravascular
hemolysis (↑LD, total bilirubin, Coombs +)
myoglobin – muscle contusion (↑ s-Mgb)
• false positive:
- menses, gynecologic (uterine cervix, vaginitis)
- artificial (malingerers),
- porphyria, dietary (red beet), drugs (rifampicine)
50
Why hematuria?
Renal:
• glomerular: glomerulonephritis, systemic diseases, hereditary
(sy of thin membranes, Alport. sy)
• tubulointerstitial: acute nephritis, toxicity, acute obstruction
• vascular: malignant hypertension, thrombosis / embolism
• other: tumors (Grawitz / Wilms), cysts, necrosis of papila, trauma,
nefrolithiasis
Postrenal:
• lithiasis, prostate, permanent urinary catheter, urothelial carcinoma,
urinary tract infection (cystitis), trauma, tuberculosis, malformation,
post-radiative, fistuli
persistent macroHU in elderly = in 20 % suspected urothelial ca
Extrarenal:
• anticoagulants, polycytemia, hematological malignancies, bleeding
51
diathesis
Hematuria / Erythrocyturia
Hematuria (HU) = blood in urine
visible - macroHU – brown color
(„Coca-cola“)
(in)visible microHU - strips / urinary
sediment („microscopy“)
Erythrocyturia = erythrocytes > 30/µl
glomerular
- glomerulonephritis,
- other glomerular diseases,
usually with PU
if HU + PU = usually GN
non-glomerular
- interstitial (nephritis, Grawitz tu, cysts),
- lower urinary tracts (urolithiasis,
infection, trauma, urothelial/renal
carcinoma, prostate)
usually only a mild PU
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Erythrocyturia typing:
1. Erythrocytes in phase contrast:
glomerular:
≥ 80 % dysmorphic or ≥ 5 % acanthocytes,
„doughnuts-cells“, erythrocyte casts
non-glomerular: ≥ 80% eumorphic
limitation: only in fresh urine, amount of cells in sediment,
subjective evaluation, experience, grey zone
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2. protein indexes (if proteinuria is present):
u-albumin/u-total protein proteinurie: glomerular
≥ 0,59
non-glomerular < 0,40
protein indexes (α2macroglobulin, IgG, α1microglobulin
und their ratios) – only in some laboratories
- more specific differentiation, objective
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Patient 4: microHU renal glomerular
male, 61 y.:
his history: 12/06 microHU, examined by an urologist
(excluded urolithiasis, lower urinary tract infection and prostate disease)
first examined by a nephrologist (1/07): exanthema, PU 2,6 g/l,
microHU, elevated IgA, urinanalysis: protein +++, blood ++++
phase contrast: 90 % dysmorphic ery, 10 % acanthocytes
PU typing: PU 2,8 g/l
↑↑↑ albumin, IgG ↑, mildly α1micro, u-Alb/total protein = 0,80
Concl.: glomerular nonselective PU, with mildly altered interstitium)
- glomerulonephritis, glomerular HU
↓
renal biopsy: focal segmental mesangioproliferative IgAN with crescents
(RPGN), Henoch-Schönlein purpur
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→ early biopsy = early therapy, recovered renal function
Urinary sediment
Basic:
morning urine, not older than 2h (destroyed elements),
carefully centrifuge, differentiate elements - flow cytometry / camera
imaging + SW analysis (+ microscopy 400x)
erythrocytes: 0 - 12 /µl
leucocytes: 0 - 20 /µl
sporadic hyaline casts (more frequent: diuretics, excercise,
fever, low water intake)
Collected urine 3 h – „Hamburger sediment“ - quantified elements
- disease „activity!
erythrocytes: ≤ 2000/min
leukocytes: ≤ 4000/min
casts:
≤ 60 - 70/min
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Leucocytes:
leucocyturia > 15 / µl
• interstitial nephritis, cystitis, urethritis, prostatitis, carcinoma,
• surrounding organ diseases (gut, gynecological)
leucocyturia without bacteriuria:
• glomerulonephritis, systemic lupus, papila necrosis, cysts,
nefrolithiasis,
• possible contaminated by vaginal fluid
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Casts:
physiological: hyaline - Tamm-Horsfall. protein (THP), sporadic
pathological: precipitates of THP + content of distal tubuli and collecting ducts:
leukocytar: interstitial nephritis, urinary tract infection, glomerulonephritis
erytrocytar: glomerular diseases (GN)
granular: glomerulonephritis, interstitial nephritis, acute tubular necrosis
wax: typical in diuresis-recovery stage just after oligo/anuria (obstruction),
chronic renal failure
• fatty – nephrotic sy
• Bacterial
• Epithelial – tubular
damaged tubuli
•
•
•
•
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Urinary syndromes
nephritic: dysmorphic erythrocytes, leucocytes, casts
GN, systemic lupus, Henoch-Schönlein purpur, systemic vasculitis
(Wegener granulomatosis, Goodpasture sy,…), hemolytic-uremic sy
nephrotic: if nephrotic proteinuria (> 3,5 g / 24 h)
hyaline and fatty casts, possible cholesterol crystals,
dysmorphic erythrocytes less frequently
glomerular diseases (MCN, FSGS, MGN, diabetic nephropathy)
minimal abnormalities: isolated microHU
IgA nephropathy, residual after acute GN, systemic lupus,
Alport sy, hypertension,…
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Concentration of urine
60
urine is hypertonic (if compared to ultrafiltrate):
- regulation: antidiuretic hormone (ADH )
stimulus: s-osmolality changes
↑ S-osmol.: (pure water loss – unconsciousness, polyuria,
↓ intake)
→ ↑ ADH → ↑ water resorption…. ↓ urine output,
concentrated urine (↑u-osmol) ….. drop in s-osmol.,
hypertonic urine
osmolality in urine >> in serum (≥ 600 mmol/kg)
If not: u-osmol. < 600: diabetes insipidus
- central (tumors, trauma hypophysis/hypothalamus)
- peripheral (interstitial nephritis, toxins, hypoK)
- mixed
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↓S-osmol.: (polydipsia)
→ very low ADH …0 → impermeabile for water, only NaCl
resorbed → hypotonic urine, low u-osmol.
osmolality in urine < in serum
If not: u-osmol. > s-osmol: SIADH (sy of inadequate ADH secretion)
(ADH secretion stimuled if not ↑ S-osmol, ↑U-osmol, ↓ S-Na)
– „water overdilution“
(pneumonia, tuberculosis, brain trauma or operation, tumors –
lung, pancreas, large operation)
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• How to test?
- (fluid restriction 24 – 36 h → u-osmol.)
-
in a daily practice: u-osmol. in morning urine = 2x s-osmol.
(approx. 600 mmol/kg), in young 900 mmol/kg (3x)
if not: isostenuria: u-osmol. = s-osmol.
(advanced chronic renal insuficiency)
- adiuretin test: (DDVAP = ADH analogue):
(DDVAP i.nas. administration in the morning, measured u-osmol. in 4 h)
u-osmol. 1100 – 800 mmol/kg H2O - age)
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osmolality:
Refer. values : serum: 275 – 295 mmol/kg H2O
urine: 400 – 900 (50 – 1200) mmol/kg H2O
(u-osmol. lower in breast-feeding and elderly)
in a daily practice – calculated osmolality:
serum = 2 x s-Na + glucose + urea
osmolal gap: big difference measured vers. calculated value
normal = 5 - 10 mmol/kg H2O
elevated: toxins (1‰ alcohol = + 23 mmol/kg H2O),
catabolism, hyperglycemia
urine = 2 x (u-Na) +(u-K) + (u-urea) + NH4+
(NH4+ – approx. 30 – 50
64mmol/d)
Minerals
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Sodium (Na)
• main extracellular cation – osmotic pressure
to evaluate together with water: Na+ retention = water retention,
Na+ overload = water overload
• regulation:
A) depleted EC fluids:
- loss of isotonic fluids (vomiting, bleeding, ascites, ileus)
= risk of collapsed circulation - blood pressure (BP) falls…
→ renin (juxtaglomerular): angiotensinogen (liver) … angiotensin-II
→ vasoconstriction … rise in blood pressure
→ aldosterone (adrenal cortex)
Na+ and water reabsorbed in distal tubulus … rise in BP
u-Na+ < u-K+, u-Na + < 20 mmol/l (< 10 mmol/l)
- loss of pure water - low ADH, ↑ S-osmol. … changes between EC
and IC space, collapsed circulation observed until severe
dehydratation
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B) excess Na + and water, expanded EC fluids – natriuretic peptides
regulates extracelular volume and blood pressure
ANP, BNP, CNP: left ventriculus and atrium, endotelium, brain, lung,
kidney, aorta, suprarenal glands
stimulus: ↑ volume / filling pressure atrial / ventricular
to protect pressure and volume overload - endogenous diuretics:
- ↑ urine output, u-Na excretion,
- against renin-angiotensin-aldosterone
- vasodilatation (sympathetic antagonists)
overloaded circulation (heart failure, left ventricular hypertrophy, renal
failure with oliguria, hyperaldosteronismus)
Reference values: serum: 135 – 146 mmol/l
urine: 50 – 220 mmol/l
FENa: 0,010 – 0,012
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Potassium (K):
• main intracellular cation (EC: IC = 4,5 : 140), irritability
• to evaluate together with acidobase - H+ (acidosis - ↑K+, alcalosis - ↓K+)
pH Δ 0,1 = 0,3 - 0,4 mmol/l K+
• regulation:
- resorbed in proximal tubulus,
- secreted in distal tubulus (K+, H+/Na+)
– aldosteron (stimulates K+ excretion)
•
elevated in urine: renal failure, loop diuretics, catabolism,
hyperaldosteronism
!! hyperaldosteronism: unclear hypoK, ↑ u- K+, u- K+ > u-Na+
• decreased in urine: extrarenal loss - gastrointestinal (K+ 3x more vers
plasma), low intake, anabolism
Reference values: serum: 3,8 – 5,4 mmol/l
urine: 45 – 100 mmol/d
FEK:
0,04 – 0,19
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Excrete fractions:
• ratio of compound XY filtred by glomeruli and excreted in definite urine
• show tubular functions: FEx = Ux x Pkr / Px x Ukr
•
•
•
•
FE H2O:
FENa:
FEK:
FEosmol.:
0,01 – 0,02
(max. 0,035)
0,004 – 0,012 (max. 0,30 – 0,40)
0,04 – 0,19
(max. 1,5 – 2,0)
< 0,035
(max. 0,035)
• without long urine collection
• diff. dg.: prerenal x renal failure
prerenal: low FENa < 0,01, (+ low u-Na + < 20 mmol/l)
(intra)renal: high FENa > 0,03, (+ u-Na + > 30 mmol/l)
69