Lecture 2 Flashcards
Renal Disease
Signs and Symptoms
- Malaise, HA, visual disturbances
- Flank pain, renal colic N/V
- Low urine output
- +/- painful urination (dysuria), hematuria or pyuria
- Hypertension
- Edema (protein loss)
- Malar rash
- Bleeding
Renal Disease
Laboratory Findings
- Increases serum blood urea nitrogen (BUN) and serum Creatine.
- Decrease creatine clearance
- Oliguria (
Blood Urea Nitrogen
Measures the amount of urea nitrogen in the blood.
Urea is formed in the liver as the end product of protein metabolism.
Urea is filtered by the glomerulus but partially reabsorbed by the tubules
BUN
Normal range
***10-20mg/dL
BUN
Serum Levels is Dependent on
Glomerular filtration rate (GFR)
Protein content in the diet
Tissue metabolism
Proximal tubule reabsorption (dependent od GFR)
Functional status of the hepatic urea cycle
Increased in BUN
CHF, Renal Failure
Shock, burns, dehydration, diuretics
Excessive protein intake, TPN
GI bleeding
Decrease in BUN
Malnutrition
Liver Failure
*** Pregnancy, SIADH (volume overload)
Azotemia
*** Nitrogen retention seen with elevated BUN
Chronic Renal Failure
*** >3 months deterioration in renal failure
consequence of the loss of functioning nephrons
Uremia
clinical term that describes the patients sign as symptoms when end-stage renal failure.
Serum Creatine
Waste product in the blood that comes from muscle activity.
- Its the breakdown product of creatine phosphate
- it directly related to skeletal muscle mass.
***The most common used indicator of renal function
Used to calculate the creatine clearance which correlates with the glomerular filtration rate GFR
Creatine normal range
.5-1.2 mg/dL
Increased Creatine Levels
Renal disease, hypovolemia and tissue necrosis, CHF heart failure, RM, burns
Drugs: ACE inhibitors, aminoglycosides (gentamicin), cimetidine (H2 blocker), NSAIDs, chemotherapeutics (cisplatin), antibiotics (trimethoprim, cefoxitin), **lithium, ***contrast dye, statins, diuretics, creatine supplements in body builders.
Decreased
Debilitation (not moving their muscle mass), decreased muscle mass
Pregnancy, SIADH (volume overload)
Acute Kidney failure
Pre-renal, Renal, Post-renal
Most things are acute
Pre-renal - hyper-perfusion of kidneys (dehydration, anemia, heart failure)
Renal- Acute tubular necrosis, Acute interstitial nephritis, Glomerulonephritis
Post-renal (think obstruction)
BPH, prostate cancer, Bladder/cervical CA obstructing ureters, stone (renal lithiasis), kinked foley catheter
BUN/ Crt ratio
Prerenal, renal, postrenal
Prerenal (>20:1)
BUN reabsorption is increased
Dehydration or hypoperfusion suspected
Renal (
Novel AKI Biomarkers
Serum and urine cystatin C
Creatinine clearance (CCr)
Volume of blood plasma that is cleared of creatinine per unit of time and is a useful measure for approximating the GFR
Creatinine Clearance (CCr) is useful to help Detect renal dysfunction Calculate dose intervals for nephrotoxic drugs
Glomerular Filtration Rate (GFR)
Volume filtered from the kidney glomerular capillaries into the Bowman’s capsule per unit of time
Best test to measure kidney function and determine stage of kidney disease
GFR and Creatinine
Inverse relationship
If GFR declines by 50%, Plasma Creatinine doubles
Clearance of creatinine is suitable estimate of GFR
The lower the GFR, the more significant the kidney damage
*Urine Osmolality
ncrease
Syndrome Inappropriate ADH Secretion (SIADH) Dehydration Glycosuria Adrenal Insufficiency High protein diet
*Urine Osmolality
Decreased
Diabetes Insipidus (diuretic effect urination a lot)
Excessive hydration (oral or intravenous)
Acute renal insufficiency
Glomerulonephritis
Urinalysis
componenets
Components Physical examination Color Clarity Specific gravity Volume Odor Chemical examination (Reagent strip) Microscopic examination
Color of urine
Color Normal – yellow or amber Due to a yellow pigment called urochrome Dark yellow – ? Dehydration Colorless - ? dilute urine or polyuria Red or red-brown – blood or hemoglobin Dark brown or black – alkaptonuria or malignant melanoma Yellow-brown to yellow-green Bilirubin or bile pigments
Clarity
Normal – clear or transparent
Cloudy/Turbid – possible bacteria or alkalinity
Odor
Normal – “urinoid”
Fruity or sweet odor – diabetic ketoacidosis
Ammoniacal odor – long standing urine
Pungent odor – urinary tract infections
(Volume)
Oliguria
decrease in normal daily urine output.
Dehydration, burns, diarrhea, vomiting.
(Volume)
Anuria
cessation of urine flow
Serious damage to the kidney
(Volume)
Nocturia
increase in the nocturnal excretion of urine
(Volume )
Polyuria
increase in the daily urine output
Diuretics, Diabetes mellitus, diabetes insipidus
Specific Gravity
Specific Gravity
Measure of the weight of solutes in water in the urine
Solutes include urea, chloride, sulfate and phosphate
Specific gravity is a crude indicator of Urine Osmolality
Reagent strip specific gravity
Gives important insight into the patient’s hydration status
Water Specific Gravity
Water Specific Gravity: 1.000
Desirable Range: 1.010-1.025
Normal Range: 1.005 to 1.030
Hydration status
1.020 indicates relative dehydration
Water Specific Gravity dtermination
Reagent dipstick
Measures the concentration of ions and gives an indirect measure of specific gravity
Increased Urine Specific Gravity
Glycosuria or increased urine protein
Syndrome of inappropriate antidiuretic hormone
Decreased Urine Specific Gravity
Diuretic use Diabetes insipidus (decreased ADH) Adrenal insufficiency Aldosteronism Impaired renal function
Specimen CollectionTiming
Timing
First morning is most concentrated
Random specimen is most common
Midstream clean-catch is preferred
Urine should be examined within one hour after voiding
Refrigerate specimen if this cannot be done
Chemical Examination
Reagent Strip
pH Specific Gravity Protein Glucose Ketones Bilirubin Nitrites Leukocyte Esterase
Urine pH
Measure of the kidney’s ability to preserve normal hydrogen ion concentration in maintenance of acid-base balance
Desirable Range: 6-6.5
Normal Range: 4.5-8
Affected by diet
More acidic: cranberries, high protein
More alkaline: citrate, vegetables, dairy products
Urine pH
Persistent alkaline urine (pH 7-8) suggests:
Urinary tract infection
Renal Tubular Acidosis
Kidneys are unable to adequately excrete hydrogen ions
Vomiting
Metabolic alkalosis
Vegetarian diet (pure vegans)
Alkalizing drugs (antibiotics, bicarbonate)
Proteus infection
Converts urea to ammonia producing an ammonia odor
Urine pH
Persistent acidic urine (pH 5-6) suggests
Acidosis Diabetes Mellitus Starvation Diarrhea Uric acid calculi Drugs (ammonium chloride)
Urine Specific Gravity
increased
Presence of glucose or protein
Urine Specific Gravity
Decreased
Diabetes insipidius
Decreased antidiuretic hormone ADH
Urine Protein
Sensitive indicator of glomerular and tubular renal function
Normally, 150 mg of protein daily (10-20 mg/dL)
Urine Protein
Reagent on dipstick is mainly sensitive to albumin (globulins, hemoglobin, fibrinogen, Bence Jones)
Normal Range: Negative or Trace
Abnormal Result 1+: 30 mg of protein per dL 2+: 100 mg/dL 3+: 300 mg/dL 4+: 1,000 mg/dL
Common causes of proteinuria
Transient proteinuria
Congestive heart failure, dehydration, emotional stress, exercise, fever, orthostatic (postural) proteinuria, seizures, pregnancy
Common causes of proteinuria
Persistent proteinuria
Glomerular causes (nephropathies, DIABETES MELLITUS, infections, malignancies (Multiple myeloma: Bence-Jones protein), DRUGS (NSAIDS, penicillamine, ACE-inhibitors), sickle cell disease, tubular causes (interstitial nephritis)
Urine Protein
False Negatives
Dilute urine
Acidic urine
Urine Protein
False Positive
Medications Penicillin, Sulfonamides Contamination Hematuria, pus, semen, vaginal secretions Alkaline urine
Urine Glucose
Glucose is normally filtered by the glomerulus, but it is reabsorbed in the proximal tubule
Excreted in urine when the plasma level exceeds the kidney threshold of 180 mg/dL or when there is a defect in the reabsorption of glucose
Glucosuria
Diabetes Mellitus Pregnancy Cushing’s syndrome Liver and pancreatic disease Impaired tubular reabsorption
Urine Ketones
Ketones are the products of fat metabolism (rather than normal glucose metabolism)
Normal result: negative for ketones
Ketonuria
Diabetic ketoacidosis, fasting/starvation, carbohydrate-free diets (Atkins), pregnancy
Urine Blood
May be in the form of intact RBCs or hemoglobin from lysed RBCs
Normal result: negative
Causes
Menses, vigorous exercise, anticoagulation therapy
Myoglobinuria – rhabdomyolysis, myocardial infarction
Hemolytic anemia, infections, calculi, tumors
Evaluating Hematuria
Complete UA (dipstick and microscopic) Culture KUB IV Pyelogram Cystoscopy Urine cytologic exam Renal biopsy
Urine Bilirubin
Normal result: negative
Bilirubinuria
Liver disease (hepatitis, cirrhosis)
**Obstructive biliary tract disease
-Biliary stasis interferes with the normal excretion of conjugated bilirubin via the intestinal tract.
-This causes a buildup in the bloodstream resulting bilirubinuria.
Urine Urobilinogen
Conjugated bilirubin in the intestinal tract is converted by bacterial action to urobilinogen
Small amount is normally excreted in the urine (up to 4 mg/d), but the major excretion is in the feces
Normal result: normal or trace
Urine Urobilinogen
increased
Increased
Any condition that causes an increase in the production in bilirubin
Hemolytic anemias, malaria
Any disease that prevents the liver from normally removing the reabsorbed urobilinogen from the portal circulation
Infectious or toxic hepatitis, congestive heart failure
Urine Urobilinogen
Decreased
Decreased
Any process that decreases bilirubin in the stool
Diminishing liver function
Obstruction of the bile ducts (cholelithiasis)
Antibiotic therapy
Suppression of normal intestinal flora
Urine Nitrite
Rapid screen for the detection of bacteria that are capable of reducing nitrates to nitrites.
-Escherichia coli (most common), Enterobacter, Proteus, Klebsiella, Pseudomonas, Citrobacter.
Positive test indicates that these organisms are present in significant numbers
> 10,000 per mL
Urine Nitrite
E.coli
Test is highly specific but not highly sensitive
Positive result is helpful, but a negative result does not rule out Urinary Tract Infection
Normal result: negative
False Positives
-Vaginal contaminant, strips exposed to air
False Negatives
-Low nitrate diet, urine not in the bladder for at least 4 hours, bacteria that lack nitrate reductase enzyme
Urine Leukocyte Esterase
Test that indicates whether white blood cells are present in the urine
Cystitis, Pyelonephritis, Urethritis (STI)
Normal result: negative
False Positives
Vaginal cellular contamination or trichomonads
*Confirmatory Tests
Ictotest – bilirubin (purple)
Clinitest – glucose
Sulfosalicylic acid – protein (hazy)
Acetest – Ketones (purple)
*Urine Microscopy
Required Reading: How to use a Microscope Powerpoint on Moodle
Summary Total magnification is the ocular lens (10x) x objective lens -Scanning lens 10x X 4x = 40x -Low power 10x X 10x = 100x -High power 10x X 40x = 400x
Specimen
Fresh sample of 10-15 mL of urine is centrifuged at 1,500-3,000 rpm for 5 minutes
The supernatant is decanted and the sediment resuspended in the remaining liquid
A single drop is transferred to a clean glass slide, and a cover slip is applied
Prussian blue stain
Hemosiderin (iron)
Clue cells
Squamous epithelial cells covered with bacteria Gardenerella vaginalis
Bacterial Vaginosis
Fishy odor
Trichomonas vaginalis
Sexually transmitted urogenital parasite
1-2 times bigger than WBC
Rapid erratic movement
Fungus
Vaginal candidiasis
Urine Crystals
Commonly found in urine sediment
Rarely clinically significant
Reported as few, moderate, many, or too numerous to count (TNTC) under microscopic high power
Cystine crystals
Flat colorless hexagonal plates
Favor acidic urine
Result of an inherited metabolic defects that prevents the reabsorption of cystine
Cholesterol crystals
Retangular plates with a notch in one or more of the corners
May be seen in those with nephrotic syndrome
Leucine crystals
Yellow spheres with concentric and radial strias
Polarized light – “maltese cross”
Seen in liver failure
Tyrosine crystals
Fine brownish needles
May be seen with liver disease
Bilirubin crystals
Yellow spheres with spicules
Conjugated bilirubin
Liver disease
Urinary Casts
Formed in distal and collecting tubules
Only a few hyaline or granular casts are normal
Normal Urinary Casts
Casts contain Tamm-Horsfall protein, which is a mucoprotein secreted only by renal tubular cells, and forms the matrix of casts
Hyaline casts
Hard to visualize as they have no inclusions
Granular casts
Degenerated cellular casts or protein aggregation
Classified as finely granular or coarsely granular
Abnormal Urinary Casts
Cellular casts
-Red blood cell casts
-Signify glomerular disease
White blood cell casts
-Associated with pyelonephritis and infection
Renal tubular epithelial cell casts
-Tubular diseases like tubular necrosis or drug toxicity
Acellular cast
*Waxy cast – seen in severe renal failure
Urine Hemosiderin
Protein that stores iron
Normal result: negative
Appears as a dark yellow-brown pigment
Positive
Hemochromatosis
Chronic hemolytic anemia
Paroxysmal nocturnal hemoglobinemia
Urinary Pregnancy Tests
- Human chorionic gonadotropin (hCG) is produced by the syncytiotrophoblast cells of the placenta after implantation (a few days after conception).
- hCG should double every 2-3 days for the first 6 weeks.
- Most chemical tests for pregnancy look for the presence of the beta subunit of hCG in blood or urine.
Urinary Pregnancy Tests
Normal results
Negative: 25 IU/L
Urinary Pregnancy Tests
False negatives results
Testing done too early
Test has too high hCG detection threshold
Medications: diuretics and promethazine
Urinary Pregnancy Tests
False positive result
Medications containing the hCG molecule
Non-pregnant production of the hCG moledule
Medications (chlorpromazine, phenothiazines, methadone)
Tests read after the suggested reaction time
Infertility treatments
hCG injections as part of infertility treatment will test positive on pregnancy tests regardless of her actual pregnancy status
Some infertility drugs (clomid) do not contain hCG hormone
*Conditions that may produce elevated hCG
Testicular tumors
Ovarian germ cell tumors
Choricocarcinoma
Gestational trophoblastic disease
Qualitative vs Quantitative
Quantitative blood tests
Can detect hCG levels as low as 1 IU/L
