UA Flashcards
What are these?
Calcium oxlate crystals
How long after urine collection should UA be run to be considered fresh?
Why do you centrifuge the sample?
60 min
Produce supernatant for dipstick and sediment for light microscopy
Specific gravity vs. urine osmolarity
SG = weight and number of solutes in urine
Osm = number of solutes in urine
What is the max dilution possible for urine in SG and osm?
1.002
~50
What is the max concentration of urine in SG and osm?
1.030
1200
(urine can’t be more concentrated than medullary interstitium tonicity)
What is the normal pH range of urine?
Under what condition would be it be >7.5?
5.0-6.5
UTI with urea-splitting bacteria (Klebsiella, proteus)
What is the most common type of nephrolithiasis?
Calcium oxlate
What happens to urine pH in a pt with metabolic acidosis?
<5.3
Diagnosis for each pt?
Pt 1: UA shows glucose+ and BS is 190
Pt 2: UA shows glucose + and BS is 90
Pt 1 = DM
(Tm of glucose transporters exceeded when BS>185)
Pt 2 = Proximal tubular dysfunction
(normal BS with glucosuria = problem with PT)
Fanconi’s syndrome (multiple myeloma, heavy metal poisoning) is associated with which UA finding?
Glucosuria
What this is?
What causes this appearance?
Crenated RBCs
RBCs in concentrated supernatant = loss of cell volume
Three conditions causing ketonuria
Fasting
DKA
Alcoholic ketoacidosis (AKA)
What ketoacids are picked up by dipstick?
What would be the tonicity of urine of such a pt?
Acetate, acetoacetate
Hypotonic (ketoacids cause osmotic diuresis)
What would you see in the urine of pt with liver dz?
Unconjugated bilirubin, urobilinogen,
(conjugated bilirubin is water insoluble so not in urine)
What disease may cause this?
Homocystinuria
(flat, 6-sided crystals)
What would cause + nitrite on UA?
What other finding might you expect?
UTI by nitrate-reducing bacteria (Gram -)
pH 7.5-8
What organism is the most likely cause of a + urine nitrite?
E coli
What would you expect to see on a UA of a pt with SLE?
Can a UTI cause the same finding?
Leukocyte esterase
(+ when increased # of PMNs in urine)
Yes
What is this?
Fatty casts
The most excreted protein under normal conditions also make up what type of cast?
Hyaline cast
(Tamm-Horsfall protein)
Normal protein excretion is <___ mg/d of what types of protein?
< 150mg/day of Tamm-Horsfall protein, LMW protein, and micro-albumin
What would you order to get a qualitative measure of urine protein? Quantitative?
UA
24 hr urine collection
What can we use to estimate quantitative proteinuria since 24 hour collection is difficult?
What value suggests nephrotic syndrome?
Spot urine sample (urine protein:creatinine)
5g/24hr = nephrotic range
What disease can cause this?
ATN, nephrotic syndrome, chronic renal failure
(granular cast)
What protein is measured by dipstick?
How can you measure all protein?
Albumin
Sulfosalicyclic acid
+ sulfosalicyclic acid test means what?
Give an example of disease that could cause this.
Tubular proteinuria
(LMW proteins exceed reabsorptive capacity of PT)
Light chain proteinuria (Bence-Jones proteins) in multiple myelome
3+ dipstick proteinuria suggests what?
Glomerular proteinuria
(increased permeability of glomerulus so albumin can get through)
What is overflow proteinuria?
What would you see on UA?
Excess production of LMW proteins exceeds resorptive capacity of PT
- dipstick (albumin can’t get through intact glomeruli), + sulfosalicyclic acid
How to tell glomerular vs tubular proteinuria
Glomerular = + dipstick, + sulf acid, albumin
Tubular = - dipstick, + sulf acid, LMW protein
What is this composed of?
Tamm-Horsfall protein
(Hyaline cast)
What would you measure on UA to assess kidney stones?
Calcium, phosphorus, uric acid
- urinary anion gap =
+ urinary anion gap =
- = high urinary NH4+ = GI loss of bicarb
+ = low urinary NH4+ = RTA = unable to excrete acids
(NH3 binds H+ in lumen when acid is secreted)
How do you calculate urinary anion gap and under what condition do you?
How does this compare to the calculation for plasma anion gap?
UAG = Na + K - Cl; to determine hyperchloremic MA
PAG = Na - HCO3 - Cl
What finding is pathognomonic for nephrotic syndrome?
Fatty casts
Maltese crosses on bifringence
How do you determine if + blood on UA is due to RBC or myoglobin/Hb?
Look for RBC in sediment, which will be absent if due to myoglobin/Hb
UA + for blood most likely due to:
Presence of RBC in sediment
Are RBC normally found in urine?
What would cause myoglobin or Hb to show up in urine?
Yes, 0-2 RBC/hpf
Rhabdo or hemolysis, respectively
What is causing the + blood on dipstick?
No RBC casts, normal RBCs in sediment, clots in urine, albumin -
Extra-renal cause (i.e. hemorrhagic cystitis, bladder CA, menstruation)
UA findings of pt with glomerulonephritis:
Blood?
RBC casts in sediment? If so, shape?
Protein?
Clots?
+
+, dysmorphic
+
-
Why is proteinuria associated with glomerular cause of hematuria but not extra-renal causes?
Duh! If glomerulus is messed up enough that blood gets through, protein will get through, too. If blood is extra-renal, the glomerulus is fine and won’t filter blood or protein!
What is pathognomonic for renal dysfunction?
RBC casts
(if absent, look for extra-renal cause of hematuria)
Name some causes of RBC casts.
Glomerulonephritis (IgA nephropathy, PSGN, Goodpasture)
Malignant HTN
Renal ischemia
Vasculitis
Why are RBCs dysmorphic in the sediment of pt with renal origin hematuria?
They get beat up as the pas through the glomerulus
What is this?
WBC cast
(Granular cytoplasm, irregular nuclei)
What type of cell in urine is called “glitter cell”? Why?
Causes of this finding?
WBC, intracellular components shine in fresh specimen
Anything inflammatory = UTI, pyelonephritis, allergic interstitial nephritis, intense glomerulonephritis, Lupus
What is the largest cell in the field?
Tubular epithelial cell
(hard-boiled egg; not a great example)
What does this finding tell you about renal function?
Nothing! This is a squamous epithelial cell (abundant cytoplasm) and is found lining the lower urinary tract = nothing to do with kidney
What is hallmark finding of ATN?
Tubular epithelial cell
(hard-boiled egg; think: if tubule is necrotizing, you should see the cells in the urine)
A marathon runner is likely to have what cast after finishing a race?
Hyaline cast
(Volume depletion = hyaline cast)
What is the matrix of all casts? Where is this produced?
Tamm-Horsfall protein in TALH
Dx?
Chronic kidney disease
(waxy cast = large, white outline, sometimes cracked, acellular, sharp broken ends)
What are the arrows pointing to?
What would cause this finding?
WBCs, inflammation
Name two conditions that could cause this finding
Tumor lysis syndrome, gout
(uric acid cystals = rhomboid)
What are “coffin-lid crystals”?
Cause?
Triple phosphate
Infection
Dx?
ATN (ethylene glycol, acute transplant rejection, heavy-metal poisoning)
(hard-bolied egg)
Dx?
Nephrotic syndrome
(fatty casts are pathognomonic for nephrotic synd)
Why do these casts form?
Breakdown of cellular debris
Very non-specific finding, can be ATN, nephrotic syndrome, chronic renal failure
Ca ox crystals
Casts associated with ATN?
Tubular epithelial (hard-bolied egg)
Granular
Name a condition in which you would see these in urine?
WBC
Dx?
Chronic renal failure
Dx:
Urine with protein and lipid
Nephrotic syndrome
Dx:
Protein, hematuria, RBC casts
Nephritic syndrome
Dx:
Hematuria, heavy proteinuria, RBC casts, lipiduria
Mixed nephrotic/nephritic syndrome
Dx:
Granular casts, SG 1.010, hematuria
Tubular damage
(can also have tubular epithelial cells)
Why does tubular injury cause SG of 1.010?
Lose ability to concentrate urine so it matches osmolarity of plasma, 300 mOsm ~ 1.010
What is pyuria?
Pus in urine
Sterile pyuria
Inflammatory tubulitis
Dx:
Pyuria, bacturia, hematuria, SG 1.010
Pyelonephritis
