5 functions of kidney
elimination, reabsorption, homeostasis (water and electrolyte balance), metabolic, endocrine
how much percent cardiac output goes through kidney
25%
responsible for the production, storage, and release of a hormone called renin which regulates blood pressure
Juxtaglomerular apparatus
renin released from where
kidney
main function to create a gradient in medulla of kidney
loop of Henle
what part of kidney has countercurrent multiplier system and an area of high urea concentration
loop of Henle
cutoff values for anuria, oliguria, polyuria,
anuria < 100 mL/day
oliguria <400 mL/day
polyuria >2L
definition oncotic pressure
created by ALB to prevent movement of water from one solution to another
what is hydrostatic pressure in kidney
The blood inside the glomerulus creates glomerular hydrostatic pressure which forces fluid out of the glomerulus into the glomerular capsule
definition uremia (azotemia)
excess blood of urea, CRE, and other nitrogen compounds
definition nephritis (glomerulonephritis)
kidney inflammation
purpose of furosemide
as a loop diuretics, inhibit Na reabsorb at the ascending loop -> water loss in urine
purpose of thiazide type diuretics, example?
example: hydrochlorothiazide ->distal convoluted tubule ->retention of water in the urine
purpose of carbonic anhydrase inhibitors is to
in proximal convoluted tubule -> inhibit enzyme carbonic anhydrase -> HCO3 accumulate in the urine -> decrease Na absorption
purpose osmotic diuretics and drawbacks
an example of osmotic diuretics
increase osmolarity but limited tubular permeability
example: glucose
purpose of Tamm-Horsfall glycoprotein
protects against bacterial UTI by blocking bacterial adherence to the bladder epithelium
most abundant urine protein
Tamm-Horsfall glycoprotein (THP)
healthy U24h? pH, total volume, color, specific gravity, abundant protein
slightly acidic (5-6), 500mL+, amber color, 1.024 specific gravity, THP
where is urine formation/water filtration
glomeruli
what is the high threshold (almost completely absorbed) of reabsorption? what is the low threshold (minimally absorbed)?
high threshold: glucose, aa
low: CRE (minimally reabsorbed),
what electrolyte highly permeable at the proximal tubule?
Na
approximately 90% of HCO3 reabsorbed where, remainder in where?
proximal tubule, remainder in distal tubule,
percentage of water reabsorbed through the kidney pathway?
70% proximal, 5% loop of Henle, 10% distal, remainder collecting duct
what is countercurrent multiplication mechanism in the kidney
spends energy to reabsorb water from the tubules -> high osmolarity in the inner medulla
regulation by countercurrent multiplier mechanism where?
loop of Henle
what part of the kidney that ADH has effect on
distal tubule, collecting duct
at kidney, what the primary hormones, secondary, catabolic (degrade hormones)?
primary: renin, erythropoietin, prostaglandin
secondary: PTH, PRL, GH
Catabolic: insulin, aldosterone,
renal blood flow can be measured by what substances
p-aminohippurate (PAH)
for a healthy glomerulus, proteins larger than what protein are retained?
larger than ALB
Glomerular Sieving Coefficient (GSC) formula
GSC = tubule plasma conc / ratio of freely permeable compound (CRE, inulin)
difference acute and chronic kidney failure
ARF: rapid, electrolyte, acid-base, fluid imbalance -> difficult to control, high mortality
CRF: small, shrunken kidney; diabetes is one of major causes
what stage of kidney failure for uremic syndrome
terminal, kidney unable to function normally
classic signs of uremic syndrome
fatigue, loss of appetite, nausea, vomiting, tremors, mental, shallow breathing, metabolic acidosis
primary lab findings of uremic syndrome
reduced GFR, high BUN, CRE, hyperP, hypoCa
hyperK (myocardial contraction and rhythm)
secondary symptoms of uremic syndrome
acidemia (increased respiration to clear carbon dioxide); anemia (low erythropoietin); osteomalacia (low 1,25-D), HTN
cause of glomerulonephritis
immune-mediated injury: SLE, Wegner's disease, IgA nephropathy
findings of acute nephritic syndrome (acute glomerulonephritis)
hematuria, proteinuria (<3g/day), reduced GFR, sodium and water retention, HTN, localized edema
RBC cast -> glomerulonephritis, hyaline + granular cast -> common, waxy cast -> chronic process
nephrotic syndrome lab findings
proteinuria (>3g/day; ALB>1.5g/day), hypoALB, hyperCHOL, fat particles, edema
high alpha-2 globulin and beta globulin
cause of nephrotic syndrome
glomerulonephritis, SLE, diabetic nephropathy
what main lab result for pyuria
leukocyte esterase
nitrite in urine is an indicator for
UTI
what test should be order for urine DM patients
microALB
3 nephropathies secondary to systemic disease
diabetic nephropathy, hypertensive nephropathy, vasculitides
what substances can cause renal calculi
Ca-oxalate, Ca-PO4, UA, cystine, Mg-NH4-PO4
5 enzymes in urea cycle
CPS I (carbamoyl phosphate synthetase I)
OTC: ornitnine
transcarbamoylase
AAS: argininosuccinate synthetase
AL:
argininosuccinate lyase
AR: arginase
T/F: urea actively reabsorbed or secreted by tubules
F
important! normal BUN/CRE
12-20
testing reagents for urea (enzyme)
monitor decrease in what absorbance
urease, glutamate dehydrogenase -> glutamate
340nm
advantages of enzyme method and chemical method for urea testing
EZ: specificity
chemical: Fearon rxn, run at 45C, faster, good for urine and serum
fearon reaction for urea method -> describe
urea + diacetyl + heat -> diazine
conversion factor from urea to urea nitrogen
28/60=0.467
where synthesize creatine
liver, kidney, pancreas,
how much free creatine convert to CRE daily
1-2%
formula CRE clearance (mL/min) or Cockgroft-gault formula
(140-age)*weight(kg)x0.85 (if female) divided by serCRE*72
eGFR formula
Cs = (Us * V*1.73) divided by A*Ps
Cs (mL plasma cleared /min; Us (urine conc of substance; V (volume flow of urine mL/min); Ps (plasma conc of substance)
important! chemical method for CRE
Jaffe-alkaline picrate -> red-orange complex
enzyme method for CRE, what pros and cons
creatininase (more specific but more expensive)
what is major product of purine catabolism
UA
UA relates to what disease
Gout
hyperuricemia -> primary and secondary causes
Primary: overproduction of purines or underexcretion of UA
Secondary: renal retention, acidemia, increased nucleic acid turnover (tumor)
what pH for UA renal stone
pH<6
what range is for hyperuricemia, for hypouricemia
serum UA > 7, serum UA <2
does UA specimen needs protein removal step, why
yes, because of protein interference, turbidity, quenching
what chemical for UA method
what product color (what absorbance)
phosphotungstic acid, PTA
PTA is reduced by UA at pH alkaline->blue color (650-700nm)
advantage of EZ method for UA testing
uricase -> more specific than phosphotungstic acid, PTA
gold standard for GFR marker
inulin
why inulin is a gold standard marker for GFR
low MW, free cross membrane, not affected by tubule (not reabsorbed, not secreted, not metabolized)
list out the endogenous markers for GFR, pros and cons
CRE: most common
urea: inadequate
CysC: better than CRE but
expensive as it uses IA
ranges for The ratio of urine osmolality to serum osmolality
normal: 1-3
after fluid restriction: 3-4.7
renal tubule
deficiency: below normal
polyuria from DI: 0.2-0.7
what substance to use to calculate renal plasma flow (RPF)
PAH: para-aminohippuric acid
what is the relationship between GFR and RPF? what is the normal in this number
the normal FF (filtration fraction) equals GFR/RPF
normal example: 120/600=20%
3 chemistry methods for total protein in urine
Lowry: copper -> bind with peptide in pH>7
Turbidimetry:
TCA (trichloroacetate) or benzethonium chloride
Dye binding:
coomassie or pyrogallol red molybdate
formula selectivity index, normal?
IgG clr / ALB clr
(P_ALB*U_IgG/U_ALB*P_IgG)
less than 0.2->high selectivity
>0.2->non-selective
important indicator of myeloma? name and what type of protein
Bence Jones Protein-> light chains
classic test for Bence Jones Protein for myeloma
heating (precipitate at 56C and redissolve as temp going to boiling point)
2 current tests for Bence Jones Protein for myeloma
electrophoresis followed by immunofixation and typing
can also be done by nephelometry
formula Fractional Excretion of Bicarbonate
FE-HCO3 = (uHCO3 x sCr) / (sHCO3 x uCr)
why we use Fractional Excretion of Bicarbonate? what range tells us what
diagnosis of renal tubular acidosis
proximal RTA: FE=10-15%; distal <10%
pink brown color of urine can be due to
Hb or myoglobin
fat particles in urine can be due to what disease
nephrotic syndrome
dipstick color indications for TP. Hb, Gluc
TP: green, yellow in absence
Hb: orange to dark green
Gluc: green to dark brown
dipstick color indications for nitrite, WBC, pH
nitrite: pink
WBC: purple
pH: orange to blue
microscopic and possible conclusion disease for RBC, polymorphonuclear leukocyte with or without cast
RBC->hematuria, glomerular disease
with: upper UTInflammation, no cast: lower
testing procedure for oxalate stones
what chemical
EZ, acidify urine pH 1.8 to solubilize all salts -> thru charcoal column to remove interference
methyl-2-hydrazone
testing procedure for citrate stones
EZ, preincubation w/out citrate lyase ->remove endogenous compounds -> serum deproteinated -> pH 8
in conclusion, what are the best indicators for loss of renal function
CREclr and GFR
what are early substances for early signs of renal loss function
proteinuria, microALBuria