UA- Dipstick Flashcards
What are the ten (and sometimes 11) tests on a dipstick?
glucose, bilirubin, ketones, SG, blood, pH, protein, urobilinogen, nitrites, leukocytes & sometimes ascorbic acid
What is normal SG? What does it measure?
1.005-1.030
1.010-1.025 for adults
1.001-1.018 for <2 yo
measures kidneys ability to concentrate urine
What is high SG indicative of? What can cause it?
high SG= concentrated urine, SG >1.025= hypersthenuria
DM, proteinuria/nephrotic syndrome, drug effects, dehydration, CHF, toxemia of pregnancy
What is low SG indicative of? What can cause it?
low SG= dilute urine, SG <1.001-1.010= hyposthenuria
increased fluids, chronic renal disease, DI, diuretics, glomerulonephritis
How does chronic renal disease present in relation to SG?
SG may consistently be at 1.010= isosthenuria
What can create a high false positive? What can create a low false positive?
high false + = proteinuria
low false + = highly buggered alkaline urine
Where is glucose normally filtered? Reabsorbed? When do you get glucosuria?
Normally filtered out in glomerulus, reabsorbed in PCT
glucosuria= blood glucose 160-180 mg/dl and thus spilling over into urine
What diseases can cause glucosuria?
DM, cushing’s syndrome, pheochromocytoma, acromegaly, chronic pancreatitis, drugs
What can produce false positives for glucose? false negatives for glucose?
false positives: oxidizing agents
false negatives: ascorbic acid, aspirin, ketones
What does increased ketones in the blood lead to?
- electrolyte imbalance
- dehydration
- acidosis & coma
What is the only ketone the dipstick can detect? What is this ketone not indicative of (what disease)?
only detects acetoacetic acid, not indicative of diabetic ketoacidosis (beta-hydroxybutyric acid is what you would see if someone has DKA)
What are the 3 types of ketones we care about?
acetoacetic acid
beta-hydroxybutyric acid
acetone
What 2 diseases have ketonuria?
- DM
2. increased metabolic states: hyperthyroidism, fever, pregnancy
What can give you a false positive for ketones?
drugs, highly pigmented urine
What can give you false negatives for ketones?
prolonged air exposure (it is volatile)
What are the three types of blood a dipstick can detect?
free hemoglobin: lysed RBCs (hemoglobinuria)
hemogloblin: intact RBCs (hematuria)
myoglobin: muscle protein
What do we need to determine if there is blood in the urine? What can it be indicative of?
Need to determine the SOURCE.
glomerular dz, kidney stones, pyelonephritis, trauma, cystitis, bladder cancer, prostate cancer, exercise hematuria, MI, contamination (vaginal secretions)
What are false positives for blood?
- microbial peroxidases
- myoglobinuria
- menstrual blood
What are false negatives for blood?
- nitrites
- increased SG decreases reactivity of test
- ascorbic acid
What is the range of pH for urine? What maintains pH balance?
4.5-8 (average of 6.0)
kidneys maintain by excretion of H+ and reabsorption of Na2+
What can an alkaline pH reading indicate? (4 things)
- alkalosis, respiratory or metabolic
- UTI
- gastric suction, vomiting, renal tubular acidosis
- vegetarians, high citrus intake
What can an acidic pH reading indicate? (6 things)
- acidosis, respiratory or metabolic
- DM
- starvation
- COPD
- UTI
- high meat, high cranberries
What is protein in urine a sensitive indicator of?
KIDNEY FXN
slit pores normally too small to allow high molecular weight proteins through, also have negative charge to repel proteins
What are fxnal renal causes of proteinuria?
- severe muscular exertion
- glomerulonephritis
- pregnancy
- nephrotic syndrome
- orthostatic proteinuria
- renal tumor or infection
What are pre-renal causes of proteinuria?
- fever
- renal hypoxia
- hypertension secretions
What are post-renal causes of proteinuria?
- cystitis
- urethritis or prostatitis
- contamination with vaginal secretions
When can transient proteinuria occur?
with fever, stress, exercise of CHF
What can cause a false positive for protein?
- vaginal secretions
- hematuria
- pyridium
- highly alkaline urine
What can cause a false negative for protein?
-dilute sample
What protein is the dipstick most sensitive to? What will it not detect?
most sensitive to albumin
won’t detect: globulins, glycoproteins, Bence-Jones proteins
What is the path of RBCs to urobilinogen excreted in the feces?
RBCs get lysed and release hemoglobin–> (globin &) heme catabolized to–> biliverdin reduced to–> unconjugated bilirubin–> to liver via albumin–> liver conjugates with glucuronic acid–> conjugated bilirubin–> into bile–> into intestines where it gets converted to urobilinogen by intestinal flora
What is excess bilirubin called? What can cause it?
increased bilirubin= bilirubinuria caused by: -gallstones -cholestasis -bile duct obstruction -acute hepatitis -congenital defects in bilirubin metabolism
False positives for bilirubin?
- fecal contamination
- pyridium indicans
False negatives for bilirubin?
- nitrites
- light
- ascorbic acid
What are normal levels of urobilinogen in urine?
0.2-1.0 mg/dL
When will you see increased urobilinogen? Decreased?
Increased: intravascular hemolysis, intestinal obstruction, early stages of hepatitis
Decreased: dipstick lacks sensitivity to test for decrease
False positives for urobilinogen?
- fecal contamination
- pigmented drug metabolites
- beets
False negatives for urobilinogen?
- formaldehyde
- prolonged air exposure
- antibiotics
What does increased nitrites indicate? What do you have to be careful about assuming though?
UTI
BUT not all bacteria convert nitrates–> nitrites so can get a false negative in this way
False positives for nitrites?
- pyridium
- beets
- bacterial growth in old samples
False negatives for nitrites?
-high SG
-low nitrate diet
-ascorbic diet
(urine doesn’t sit in bladder long enough/not in contact with bacteria long enough)
What does a positive leukocyte test indicate?
UTI most likely
pts can be asx even w/significant infection
What are 2 non-urinary causes of pyuria?
- appendicitis
- pancreatitis
False positives for leukocytes?
vaginal secretions
False negatives for leukocytes?
- glucose
- protein
- increased SG
- some antibiotics
- oxalates
